Re: [CentOS-virt] CentOS 6 VM image for paravirtualizaton on CentOS Xen server
On Mon, Mar 16, 2015 at 10:32 PM, Nico Kadel-Garcia nka...@gmail.com wrote: On Mon, Mar 16, 2015 at 4:02 AM, Manuel Wolfshant wo...@nobugconsulting.ro wrote: Quote from an actual installation: [root@xenh4 ~]# history| grep virt virt-install -n dhcpdns -p -r 1024 --os-type=linux --vnc -f /var/lib/xen/images/dhcpdns -s 2 -l http://192.168.50.40/mrepo/centos6-i386/disc1 -x ks=ftp://192.168.50.40/linux/ks-minimalC6-xen.cfg; [root@xenh4 ~]# uname -a Linux xenh4 2.6.18-400.1.1.el5xen #1 SMP Thu Dec 18 02:18:37 EST 2014 i686 i686 i386 GNU/Linux https://github.com/CentOS/Community-Kickstarts/blob/master/ks-minimalC6.cfg is quite close to the above mentioned ks-minimalC6-xen.cfg ( actually both are descendants of the same template of mine ) Thanks The key, hinted at by various notes in this thread, was the use of the --location to point to a network accessibleinstallation repository. I'm afraid that the Xen wiki directions about --location are a bit unclear about the need for this to be the base of a deployment directory, one that *must* have a working subdirectory called 'imagex/xen' with the relevant files in it. I admint, I have to just love hardcoded, hidden requirements!!! I'll point out for others who may need to image systems quickly that it's often more effective, especially in terms of speed and external bandwidth, to use an internal mirror as you did. I'll also point out that it can be awfully handy to keep such a mirror up-to-date and use it your local configurations. I publish such scripts at https://github.com/nkadel/nkadel-rsync-scripts, in case anyone else wants them. I'll also mention my old habit in ks.cfg files of doing this, to hang onto the actual ks.cfg instead of the confused and '%pre' and '%post' stripped, anaconda reverse engineered oddness in /root/anaconda-ks.cfg. %pre cp -f /tmp/ks.cfg /mnt/sysimage/root/ks.cfg %end ___ Nico, I wrote tutorials on how to do this when I was using xen. I haven't used these tutorials in a couple of years but they worked then so they should still work now. This is for an automated CentOS 6 (x86_64). http://grantmcwilliams.com/item/538-centos-6-virtual-machine-64-bit-installation-on-xen Grant McWilliams http://grantmcwilliams.com/ Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Xapi packages in CentOS xen-c6 repo: first steps
I'd like to test them as soon as you get ANY repo up. Grant McWilliams http://grantmcwilliams.com/ Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. On Tue, Jul 2, 2013 at 11:23 AM, Dave Scott dave.sc...@eu.citrix.comwrote: Hi, Thanks Mike for bringing this up. On Jul 2, 2013, at 6:15 PM, Mike McClurg mike.mccl...@citrix.com wrote: Hi list, Dave Scott has been working on a prototype of XenServer's Xapi running on stock CentOS 6.4 x86_64, with libvirt and ceph integration. He plans to demo this at the CentOS dojo in Aldershot next week. We'll be publishing the RPMs for this in a public Yum repo, and we would really like for these RPMs to eventually live in the xen-c6 repo. I was wondering what are the steps for making this happen, and also if it would be possible to make this happen before the dojo next Friday (12 July). My RPMS are in a bit of an experimental state, and I'd really appreciate people's feedback. It might be too soon to merge them into xen-c6 by next week, but it would be nice if I could point people at an online copy somewhere. Perhaps we could make a xen-c6-experimental repo or something? I could then rsync new builds regularly and put setup instructions on the CentOS wiki. Cheers, Dave We can provide a public Yum repository with these SRPMS and RPMS, if that would help. Thanks, Mike ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] turning off udev for eth0
On Tue, Jan 3, 2012 at 8:52 AM, James B. Byrne byrn...@harte-lyne.cawrote: I have set up a kvm host and configured a standard clone prototype for generating new guests. One persistent (pun intended) annoyance when cloning is the behaviour of udev with respect to the virtual network interface. The prototype is configured with just eth0 having a dedicated IP addr. When the prototype is cloned udev creates rules for both eth0 and eth1 in the clone. Because eth1 does not exist in the cloned guest one has to manually edit /etc/udev/rules.d/70-persistent-net.rules to get rid of the bogus entries and then restart the clone instance to have the changes take effect. All this does is return the new guest to the prototype eth0 configuration. Is there no way to alter udev's behaviour? Is udev even needed on a server system using virtual hardware? Altering the rules file not a big deal in itself but it adds needless busywork when setting up a new guest. -- *** E-Mail is NOT a SECURE channel *** James B. Byrnemailto:byrn...@harte-lyne.ca Harte Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3 I do this on VM clones. It depends on your OS but where I've had to do it is with Ubuntu VMs. I'm not sure where exactly they set that in CentOS but I'd start looking in /lib/udev/rules.d/75-persistent-net-generator.rules Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Should I switch and if so what is the procedure
On Fri, Oct 7, 2011 at 8:03 AM, Ed Heron e...@heron-ent.com wrote: On Thu, 2011-10-06 at 01:46 +0200, Dennis Jacobfeuerborn wrote: ... The question is what does Xen offer that KVM cannot provide? Looking at the slides of the KVM Forum 2011 ( http://www.linux-kvm.org/page/KVM_Forum_2011) there seem to be many interesting improvements in the pipeline so at some point the question really is why hold on to Xen at all when there is not real reason to? ... For me, it isn't why hang onto Xen?, it's why convert my 18 virtualization servers? Most of my servers are remote. I have 8 physical locations. Each location has a spare server for redundancy. To change to anything else, I'd need a compelling reason as the time and effort and, potentially, travel expenses would be significant. Looking at scheduled CentOS 5 EOL, I can get other things done before having to tackle major upgrades. When I do start working on my next iteration of my system design, I'll be considering all hypervisors. And in addition to that if it isn't broken CentOS 5.7 just came out so it's not like it's an old unsupported distribution and I bet that isn't the last update that Redhat will do. I just moved some of my VMs to XCP as a test which is using the exact same version of the Xen hypervisor that I was running before. In my opinion the Hypervisor isn't really that important anymore. What's more important is the management tools for them. With the Cloud.com acquisition by Citrix, OpenStack and more I think one would spend more time thinking of these tools than which hypervisor to use. Another point would be that the Dom0 doesn't really matter that much. It's not like you'll ever change it outside of adding security patches. By desgin the Dom0 just sits there and manages DomU's. If anything the DomU OS is more important. Grant McWilliams http://grantmcwilliams.com/ Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 21, 2010 at 3:29 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB __ Do you suppose you could get it to use Phoronix Test Suite so we can start to have measurable stats? We could do the same thing for any VM software - even the ones that don't allow publishing stats in the EULA... I'm also wondering if we should do the whole test suite or a subset. Here is the list of tests.. aio-stress apache battery-power-usage blogbench bork build-apache build-imagemagick build-linux-kernel build-mplayer build-mysql build-php bullet bwfirt byte c-ray cachebench compilebench compliance-acpi compliance-sensors compress-7zip compress-gzip compress-lzma compress-pbzip2 crafty dbench dcraw doom3 encode-ape encode-flac encode-mp3 encode-ogg encode-wavpack espeak et etqw-demo-iqc etqw-demo etqw ffmpeg fhourstones fio fs-mark gcrypt geekbench gluxmark gmpbench gnupg graphics-magick gtkperf hdparm-read himeno hmmer idle-power-usage idle iozone j2dbench java-scimark2 jgfxbat john-the-ripper juliagpu jxrendermark lightsmark mafft mandelbulbgpu mandelgpu mencoder minion mrbayes n-queens nero2d network-loopback nexuiz-iqc nexuiz npb openarena openssl opstone-svd opstone-svsp opstone-vsp padman pgbench phpbench postmark povray prey pybench pyopencl qgears2 quake4 ramspeed render-bench scimark2 smallpt-gpu smallpt smokin-guns specviewperf10 specviewperf9 sqlite stream stresscpu2 sudokut sunflow supertuxkart systester tachyon tiobench tremulous trislam tscp ttsiod-renderer unigine-heaven unigine-sanctuary unigine-tropics unpack-linux urbanterror ut2004-demo vdrift-fps-monitor vdrift video-cpu-usage video-extensions warsow wine-cloth wine-domino wine-fire2 wine-hdr wine-metaballs wine-vf2 wine-water x11perf x264 xplane9-iqc xplane9 yafray Grant McWilliams . ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Thu, Oct 21, 2010 at 12:50 PM, Grant McWilliams grantmasterfl...@gmail.com wrote: On Thu, Oct 21, 2010 at 3:29 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/21/2010 12:01 AM, Grant McWilliams wrote: So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? I am trying to create just that - a kickstart that will build a machine as a Xen dom0, build 4 domU's, fire up puppet inside the domU's do the testing and scp results into a central git repo. Then something similar for KVM. will get the basic framework online today. - KB __ Do you suppose you could get it to use Phoronix Test Suite so we can start to have measurable stats? We could do the same thing for any VM software - even the ones that don't allow publishing stats in the EULA... I'm also wondering if we should do the whole test suite or a subset. Here is the list of tests.. One thing that I think probably needs to be modified for our needs is a Dom0 controller to run various tests in each DomU simultaneously then collate the date. Virtual worlds are more complex than non-virtual ones. Sometimes something runs great in on VM but drags when multiple VMs are being used. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
If I understand that paper correctly, HVM+VT-d outperforms PV by quite a lot (if you have VT-d support on your system). Thanks for that link. Just to make my criticism of the initial claim more clear: I don't claim that HVM can never be faster than PV but that you need to understand when exactly this is the case. For example I'm not sure that x86_64 vs. x86 really enters into this but I can definitely see VT-d making an impact there. Regards, Dennis Even though this is Intel talking I'd still be very sceptical of getting those numbers since this is quite the opposite of what I've seen. Maybe the vt-d is getting good enough to actually accelerate IO operations but even so that would only happen on the latest hardware. I will say that Xen has a really long packet path though. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Wed, Oct 20, 2010 at 6:24 AM, Tom Bishop bisho...@gmail.com wrote: Ok so I'd like to help, since most folks have Intel Chipsets, I have a AMD 4p(16 core)/32gig memory opteron server that I'm running that we can get some numbers onbut it would be nice if we could run apples to apples...I have iozone loaded and can run that but would be nice to run using the same parametersis there any way we could list the types of test we would like to run and the actual command with options listed and then we would have some thing to compare at least level the playing field...KB, any thoughts, is this a good idea? On Wed, Oct 20, 2010 at 6:52 AM, Karanbir Singh mail-li...@karan.orgwrote: On 10/20/2010 12:35 PM, Dennis Jacobfeuerborn wrote: Being skeptical is the best approach in the absence of verifiable/falsifiable data. Today or tomorrow I'll get my hands on a new host system and although it is supposed to go into production immediately I will probably find some time to do some rudimentary benchmarking in that regard to see if this is worth investigating further. Right now I'm That sounds great. I've got a machine coming online in the next few days as well and will do some testing on there. Its got 2 of these : Intel(R) Xeon(R) CPU E5310 So not the newest/greatest, but should be fairly representative. planning to use fio for block device measurements but don't know any decent (and uncomplicated) network i/o benchmarking tools. Any ideas what tools I could use to quickly get some useful data on this from the machine? iozone and openssl speed tests are always a good thing to run as a 'warm up' to your app level testing. Since pgtest has been posted here already, I'd say that is definitely one thing to include so it creates a level of common-code-testing and comparison. mysql-bench is worth hitting as well. I have a personal interest in web app delivery, so a apache-bench hosted from an external machine hitting domU's / VM's ( but more than 1 instance, and hitting more than 1 VM / domU at the same time ) would be good to have as well. And yes, publish lots of machine details and also details on the code / platform / versions used. I will try to do the same ( but will limit my testing to whats already available in the distro ) thanks - KB __ So what we're on the verge of doing here is creating a test set... I'd love to see a shell script that ran a bunch of tests, gathered data about the system and then created an archive that would then be uploaded to a website which created graphs. Dreaming maybe but it would be consistent. So what goes in our testset? Just a generic list, add to or take away form it.. - phoronix test suite ? - iozone - kernbench - dbench - bonnie++ - iperf - nbench The phoronix test suite has most tests in it in addition to many many others. Maybe a subset of those tests with the aim of testing Virtualization would be good? Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] performance differences between kvm/xen
On Sat, Oct 16, 2010 at 12:58 PM, Dennis Jacobfeuerborn denni...@conversis.de wrote: On 10/16/2010 08:11 PM, Pasi Kärkkäinen wrote: On Thu, Oct 14, 2010 at 02:16:42PM +0100, Bart Swedrowski wrote: Hi Karanbir, On 14 October 2010 19:59, Karanbir Singhmail-li...@karan.org wrote: On 10/14/2010 07:48 AM, Tom Bishop wrote: I think xen is still on top in terms of performance and featuresnow that is indeed what it 'feels' like, but I'm quite keen on putting some numbers on that. I have done some testing some time ago on one of the EQ machines that I got from hetzner.de. Full spec of the machine was as following: Note that 64bit Xen guests should be HVM, not PV, for best performance. Xen HVM guests obviously still need to have PV-on-HVM drivers installed. 32bit Xen guests can be PV. Hm, why would HVM be faster than PV for 64 bit guests? Regards, Dennis lol, there's seems to be a lot of hearsay surrounding performance and Xen. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] which virtualization platform to choose
On Tue, Jul 27, 2010 at 10:52 PM, Luke S Crawford l...@prgmr.com wrote: Grant McWilliams grantmasterfl...@gmail.com writes: I'm not sure any of the rest of us have ever had to recompile the kernel to get xen to work either. I have 160 or so DomUs on CentOS Dom0s and still haven't recompiled a kernel. how many guests per dom0? for my smallest plans I approach 160 DomUs per dom0, and I /have/ had to recomplile to make that work. (though, it's been rather a long time since I tried it with a CentOS/xen kernel rather than a xen.org kernel.) What kind of situation would you be trying to run 160 DomUs per Dom0? I'd be curious about your particular needs for having that many DomUs per Dom0. Did you run into a hard coded limit on the number of DomUs you could have? Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] RHEL 5.5 Xen fixes
On Wed, Mar 31, 2010 at 11:38 AM, Pasi Kärkkäinen pa...@iki.fi wrote: Hello, RHEL 5.5 has been released, and it contains many Xen related fixes. Here's the most important of the them.. fixing a dom0 caching bug which could cause domU disk corruption when the domU disk was accessed from dom0 after the domU was shutdown. Most people noticed this bug when pygrub used wrong (cached) information. pygrub uses cached and eventually outdated grub.conf, kernel and initrd: https://bugzilla.redhat.com/show_bug.cgi?id=466681 And some more: Xen hypervisor doesn't mask xsave feature from the guest; Fedora 11 PV domU kernel crashes: https://bugzilla.redhat.com/show_bug.cgi?id=524719 [RHEL-5 Xen]: F-11 Xen 64-bit domU cannot be started with 2047MB of memory: https://bugzilla.redhat.com/show_bug.cgi?id=502826 Boot hang when installing HVM DomU: https://bugzilla.redhat.com/show_bug.cgi?id=524052 [RHEL5 Xen]: PV guest crash on poweroff: https://bugzilla.redhat.com/show_bug.cgi?id=540811 [RHEL5 Xen]: Cpu frequency scaling is broken on Intel: https://bugzilla.redhat.com/show_bug.cgi?id=553324 RHEL 5.5 kernel changelog: http://rhn.redhat.com/errata/RHSA-2010-0178.html Work-in-progress (Not yet in 5.5): Grub2 guest support for RHEL5 Xen pygrub: https://bugzilla.redhat.com/show_bug.cgi?id=577511 -- Pasi Are these changes in the kernel or changes to the installed Xen? I'm wondering if this effects anyone using Xen 3.4 or newer. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Silly question about KVM
On Wed, Mar 17, 2010 at 12:02 PM, Scot P. Floess sflo...@nc.rr.com wrote: Sure, I understand the support until 2014...was more thinking of moving to 6 and beyond... People focus on this a lot but really you might have 1 machine that needs Dom0 support and 50 that need DomU support. The majority of Virtual Machines will need DomU support which will be included indefinitely. Dom0 support is already becoming a pain but either that will be fixed by a) Xen Dom0 getting into the mainline kernel b) someone create a stripped down Dom0 OS just for the hypervisor. Effectively this is what XCP is doing I think. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] moving from Xen to KVM
On Wed, Mar 17, 2010 at 6:35 AM, Dennis J. denni...@conversis.de wrote: On 03/17/2010 02:15 PM, Hildebrand, Nils, 232 wrote: Hi, I have 31 DomUs up and running on a single Box - and have a strong feeling that even 60 will run flawless. But: All of them are Para-Virtualized. I have no problem with disk IO-Bottlenecks since my DomUs are not Database-Servers - so there is mostly static information in the filesystems. The term paravirtualization is becoming quite dated. Even if you install a KVM guest without that option if you choose the virtio driver inside then you still end up with paravirtualized I/O. With the advent of things like nested page tables and SR-IOV the fully virtualized=slow, paravirtualized=way faster logic is no longer necessarily true at least not for every aspect of the system. Regards, Dennis In the Xen world paravirtualizing will be replaced by Hybrid virtualizing. As hardware virt becomes faster (ie, not so slow) then Xen will change to using HVM as the default and paravirtualize EVERYTHING else. This is not the same thing as KVM which uses hardware virt for cpu, emulation for most things except disk and network which are paravirtualized (if chosen). I look forward to this as HVM in Xen is slower than KVM even though it's kind of doing the same thing. However, I don't think people have benchmarked either enough to realize how much of a hit we're taking with virtio. KVM has some neat tricks up their sleeve as well like shared memory, nesting etc.. I may put up a KVM box just because I need nesting (for a classroom to teach virtualization). Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Thoughts on storage infrastructure for small scale HA virtual machine deployments
If all the 40 VMs start copying files at the same time that would mean that the bandwidth share for each VM would be tiny. Would they? It's a possibility, and fun to think about, but what are the chances? You will usually run into this with backups, cron, and other scheduled [non-business load] tasks. These are far cheaper to fix with manually adjusting schedules than any other way, unless you are rolling in dough. I have a classroom environment where every VM is always doing the same thing in step ie. formatting partitions, installing software etc.. We hit the disk like a bunch of crazy people. I'm replacing my setup with three Intel SSDs in a RAID0 with either iSCSI or ATAoE. The RAID0 will be synced to a disk based storage as backup. We'll see pretty soon how many concurrent disk based operations this setup can handle. I'll be bonding 3 or 4 of the iSCSI box ethernet cards and then going from there to see what each of the servers in the cloud needs as far as their connection. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Xen Database vms
for Databases! I've done the mysqlbench test on the same machine with the same database with using LVM and img files and with .img files I got within 5% of the Dom0 speed. When I moved the DomU to using LVM I got within 1% of Dom0 speed. This is the one instance where there's a definite advantage to LVM over img files. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Slightly OT: FakeRaid or Software Raid
On Wed, Dec 2, 2009 at 9:51 PM, Christopher G. Stach II c...@ldsys.netwrote: - Grant McWilliams grantmasterfl...@gmail.com wrote: Portability is no different with a RAID controller as long as you've standardized on controllers. For this to be true, it would have to be absolute. Since many people have evidence that it is not true, it's not absolute. Controllers of the same revision and firmware version have had portability problems. -- Christopher G. Stach II Like I said in our environment we have hundreds of drives moving between controllers *every month and have had zero problems with it. Not all machines use the same controller (some are 3ware 9550SX and some are 3ware 9650SE) nor do they use the same firmware version. We've been doing this for 3 years now and have never had a drive have problems. All drives are initialized, partitioned, formatted and populated with content in 3 locations around the world and then multiple sets are shipped to 75 machines in various geographical zones and used for one month. At this point we've done close to 10,000 swaps (300/month) and we've never had a controller not see a drive and recognize it without anything more than a tw_cli rescan. You can talk theoretics but I can tell you my real world experience. I cannot speak for other vendors but for 3ware this DOES work and is working so far with 100% success. I have a bunch of Areca controllers too but the drives are never moved between them so I can say how they'd act in that circumstance. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Slightly OT: FakeRaid or Software Raid
On Wed, Dec 2, 2009 at 9:48 PM, Christopher G. Stach II c...@ldsys.netwrote: - Grant McWilliams grantmasterfl...@gmail.com wrote: Interesting thoughts on raid5 although I doubt many would agree. That's okay. We all have our off days... Here's some quality reading: http://blogs.sun.com/bonwick/entry/raid_z http://www.cyberciti.biz/tips/raid5-vs-raid-10-safety-performance.html http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt http://www.miracleas.com/BAARF/1.Millsap2000.01.03-RAID5.pdf http://www.codinghorror.com/blog/archives/001233.html http://web.ivy.net/carton/rant/ml/raid-raid5writehole-0.html Maybe you are thinking of RAID 6. I don't see how the drive type has ANYTHING to do with the RAID level. IOPS, bit error ratio, bus speed, and spindle speed tend to factor in and are usually governed by the drive type. (The BER is very important for how often you can expect the data elves come out and chew on your data during RAID 5 rebuilds.) You will use those numbers to calculate the number of stripe segments, controllers, and disks. Combine that with the controller's local bus, number of necessary controllers, host bus, budget, and other business requirements and you have a RAID type. a RAID 10 (or 0+1) will never reach the write... performance of a RAID-5. (*cough* If you keep the number of disks constant or the amount of usable space? Things working tends to trump CapEx, despite the associated pain, so I will go with amount of usable space.) No. -- Christopher G. Stach II Nice quality reading. I like theories as much as the next person but I'm wondering if the Toms Hardware guys are on crack or you disapprove of their testing methods. http://www.tomshardware.com/reviews/external-raid-storage,1922-9.html Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Slightly OT: FakeRaid or Software Raid
On Thu, Dec 3, 2009 at 6:08 AM, Christopher G. Stach II c...@ldsys.netwrote: - Grant McWilliams grantmasterfl...@gmail.com wrote: On Wed, Dec 2, 2009 at 9:48 PM, Christopher G. Stach II c...@ldsys.net wrote: - Grant McWilliams grantmasterfl...@gmail.com wrote: a RAID 10 (or 0+1) will never reach the write... performance of a RAID-5. (*cough* If you keep the number of disks constant or the amount of usable space? Things working tends to trump CapEx, despite the associated pain, so I will go with amount of usable space.) No. -- Christopher G. Stach II Nice quality reading. I like theories as much as the next person but I'm wondering if the Toms Hardware guys are on crack or you disapprove of their testing methods. http://www.tomshardware.com/reviews/external-raid-storage,1922-9.html They used a constant number of disks to compare two different hardware implementations, not to compare RAID 5 vs. RAID 10. They got the expected ~50% improvement from the extra stripe segment in RAID 5 with a serial access pattern. Unfortunately, that's neither real world use nor the typical way you would fulfill requirements. If you read ahead to the following pages, you have a nice comparison of random access patterns and RAID 10 coming out ahead (with one less stripe segment and a lot less risk): http://www.tomshardware.com/reviews/external-raid-storage,1922-11.html http://www.tomshardware.com/reviews/external-raid-storage,1922-12.html -- Christopher G. Stach II So if I have 6 drives on my RAID controller which do I choose? If I have to add two more drives to the RAID 10 to equal the performance of a RAID 5 I could just make it a RAID 5 and be faster still. RAID 5 is faster than RAID 10 for reads and writes. However, you are right on the IOs. The RAID 10 pretty much trounced RAID 5 on IOs in all tests. What wasn't in the test (but is in others that they've done) is RAID 6. I'm not sure I'm sold on it because it gives us about the same level of redundancy as RAID 10 but with less performance than RAID 5. Theoretically it would get soundly trounced by RAID 10 on IOs and maybe be slower on r/w transfer as well. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Slightly OT: FakeRaid or Software Raid
On Wed, Dec 2, 2009 at 2:44 PM, Ben M. cen...@rivint.com wrote: Thanks for sharing Grant. Your point about hardware raid is well taken. However, the discussion is about Fake-Raid vs. Software RAID1 and controller/chipset dependence and portability. The portability of a software RAID1 hard drive to an entirely different box is, I have learned, much higher and less time consuming. Portability is no different with a RAID controller as long as you've standardized on controllers. Our situation is not standard but hundreds of drives are swapped between machines throughout the month without an issue. We use RAID sets to transfer large amounts of data (TBs) between machines. All systems use 3ware 9550 or 9650 controllers though so you throw the set in and rescan an it's there. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Slightly OT: FakeRaid or Software Raid
Personally, I never touch raid5, but then, I'm on sata. I do agree that there are benifits to hardware raid with battery backed cache if you do use raid5 (but I think raid5 is usually a mistake, unless it's all read only, in which case you are better off using main memory for cache. you are trading away small write performance to get space; with disk, space is cheap and performance is expensive, so personally, if I'm going to trade I will trade in the other direction.) Interesting thoughts on raid5 although I doubt many would agree. I don't see how the drive type has ANYTHING to do with the RAID level. There are different RAID levels for different situations I guess but a RAID 10 (or 0+1) will never reach the write or read performancehttp://www.tomshardware.com/reviews/external-raid-storage,1922-9.htmlof a RAID-5. The disk space waste isn't too much of a problem anymore because as you say drives are getting much cheaper. Although on that subject I'll mention that enterprise drives and desktop drives are NOT the same thing. We deal in hundreds of drives and see about a 3% failure on desktop drives and only a fraction of that on enterprise drives. I will say though that in my opinion the one really important thing to consider is the price. These controllers aren't cheap and if you skimp you will pay. For sequential single reads (streaming one stream) I'd consider using a software RAID 0. For a mirror I'd consider Software RAID but once I get serious and go for RAID5 or RAID6 I'd only use Hardware RAID. That's my 2 cents. :-) Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] XEN and RH 6
On Tue, Nov 10, 2009 at 4:36 AM, carlopmart carlopm...@gmail.com wrote: Pasi Kärkkäinen wrote: On Tue, Nov 10, 2009 at 01:20:11PM +0100, carlopmart wrote: Pasi Kärkkäinen wrote: On Tue, Nov 10, 2009 at 11:27:57AM +0100, carlopmart wrote: Pasi Kärkkäinen wrote: Still it isn't official, but Citrix XenServer will disappears soon ... It will be integrated under Microsoft Hyper-V Uhm.. I don't believe this. Where did you read that? Citrix XenServer was opensourced last week, or the hypervisor+tools part, the xencenter management interface remains closed source (but it can also manage hyper-v). IMHO, it isn't a good option to maintain domO virt servers based on CentOS or RHEL now ... It is the time to migrate to another solutions ... RHEL5, with Xen, will be fully supported by Redhat until 2014. They have clearly stated that many times. -- Pasi Ok, I think I haven't explained well, sorry. Citrix Xenserver's hypervisor and tools was donated by Citrix last week, correct. But Citrix didn't release more versions of the product because it does not intend to develop it and apply new features. Citrix virtualization bussiness will be focused only on Management and Desktop virtualization using Hper-V as a first platform and second VMware. Where did you read this? You write it like it's a fact - I haven't seen that anywhere.. ?? This will be announced over next weeks ... Again, are you speculating, or is this a fact? I think Citrix XenServer 5.7 will be released soon :) Ok, stay and wait. But I repeat: Citrix will focused his efforts only on Management and Desktop virtualization, not on servers. First past it is do it: donate xenserver to opesource community. If this is true it will not only be the death of Xen but of Citrix as well. I don't see a company surviving that only makes a gui to manage someone else's VM solution. I think Microsoft is capable of making their own GUI. I do think that we should probably just give up on getting xen in the kernel for Dom0. It's clear that the kernel guys will never let this happen. Xen may very well become a distribution providing a Dom0. The DomU stuff is already in the kernel so a very light distribution that only provides networking tools, security tools and the Dom0 code would be fine for those who want to continue using Xen. I've not been convinced that KVM is quite ready to do what Xen does. I use it but not for production. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] XEN and RH 6
Which I guess makes describing a guest as fully virtualized or paravirtualized rather pointless given that there now is just a degree of how paravirtualized a guest is depending on the drivers you use. Regards, Dennis I disagree completely. KVM or Xen HVM are fully virtualized except for two drivers. This is not the same thing as paravirtualized. People seem to think the only thing a computer does is access the disk and network device. With a PV everything is running native and the only overhead is from the Hypervisor. In a most cases using the VT bits in the CPU makes the virtualization slower in all aspects. This may not be the case in the future. The developers of VirtualBox have documented this. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Xen to KVM migration
On Mon, Oct 12, 2009 at 5:48 AM, Dennis J. denni...@conversis.de wrote: Hi, I'm thinking about how to go about migrating our Xen VMs to KVM. Migrating the configuraton should be easy using the virsh dumpxml/define commands but what is the best way to transfer the (logical volume based) images without too much downtime for the guest system? Can rsync operate on logical volumes? If so I could potentially use dd to transfer an initial copy of the image to the destination host and then shut down the guest, rsync the logical volumes which shouldn't take too long as not much data has to be transfered thanks to the initial dd and then boot the guest on the new machine. Is something like this possible or would you do something different? Regards, Dennis Can't you just use the LV in place with KVM? Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Xen to KVM migration
On Mon, Oct 12, 2009 at 10:30 AM, Dennis J. denni...@conversis.de wrote: On 10/12/2009 06:17 PM, Grant McWilliams wrote: On Mon, Oct 12, 2009 at 5:48 AM, Dennis J. denni...@conversis.de mailto:denni...@conversis.de wrote: Hi, I'm thinking about how to go about migrating our Xen VMs to KVM. Migrating the configuraton should be easy using the virsh dumpxml/define commands but what is the best way to transfer the (logical volume based) images without too much downtime for the guest system? Can rsync operate on logical volumes? If so I could potentially use dd to transfer an initial copy of the image to the destination host and then shut down the guest, rsync the logical volumes which shouldn't take too long as not much data has to be transfered thanks to the initial dd and then boot the guest on the new machine. Is something like this possible or would you do something different? Regards, Dennis Can't you just use the LV in place with KVM? I may be wrong about this but isn't running KVM on top of the Xen hypervisor a problem? Maybe this has changed but I thought in order to be able to use KVM you first have to disable the Xen hypervisor and boot into the regular Kernel. Regards, Dennis But once you have your XEN DomU config file converted to KVM you could in effect just reboot the Dom0 into a standard kernel and use KVM. Unless of course you're only moving one DomU to KVM then it wouldn't work. Grant McWilliams ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Resizing disks for VMs
On Mon, Sep 28, 2009 at 6:43 AM, Dennis J. denni...@conversis.de wrote: Hi, Is there a way to make a PV xen guest aware of a size change of the host disk? In my case I'm talking about a Centos 5.3 host using logical volumes as storage for the guests and the guests running Centos 5.3 and LVM too. What I'm trying to accomplish is to resize the logical volume for the guest by adding a few gigs and then make the guest see this change without requiring a reboot. Is this possible maybe using some kind of bus rescan in the guest? Regards, Dennis Last time I checked this wasn't supported. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] dummy ethernet interfaces
On Fri, Jan 23, 2009 at 10:29 AM, Grant McWilliams grantmasterfl...@gmail.com wrote: On Fri, Jan 23, 2009 at 10:08 AM, Caitlyn O'Hanna raven...@virtualxistenz.com wrote: No takers on this issue? --Caitlyn ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt Caitlyn, Are you sure you're only getting 100Mb or is it identifying itself as 100Mb? Actual speed and info it's applied to itself may be different. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. I just tested my dummy0 network connection and I can scp at 40MB/sec which definitely puts it above the 100Mb/sec limit. Where does it identify itself as being 100Mbit? Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] [GLPI #0000037] Zweirad Stadler | Neues Ticket - powernow error in Xen VM with new kernel
On Thu, Jan 22, 2009 at 3:55 PM, Phil Schaffner p.r.schaff...@ieee.orgwrote: On Thu, 2009-01-22 at 14:31 +0100, Kai Schaetzl wrote: Anyone else getting these tickets from sysad...@zweirad-stadler.de quoting old messages to this list directly to his mailbox? No. Haven't seen that particular spam technique before. Phil ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt Yes, I figured it was spam. Grant McWilliams Some people, when confronted with a problem, think I know, I'll use Windows. Now they have two problems. ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] xen 3.2
On Wed, Jul 16, 2008 at 1:59 AM, Rudi Ahlers [EMAIL PROTECTED] wrote: Grant McWilliams wrote: On Mon, Jul 14, 2008 at 2:46 PM, Daniel de Kok [EMAIL PROTECTED] mailto: [EMAIL PROTECTED] wrote: On Mon, Jul 14, 2008 at 5:04 PM, Justin Lim [EMAIL PROTECTED] mailto:[EMAIL PROTECTED] wrote: Any ideal when 3.2 xen will be avail for centos? When the upstream distribution provides it. I am not sure if it is on their roadmap. Of course, you could also use Xen 3.2 from XenSource, but that's not supported here. Take care, Daniel ___ CentOS-virt mailing list CentOS-virt@centos.org mailto:CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt I was at a recent Linux convention and it seemed very likely that Xen is no longer Redhat's priority at all and would love to put KVM in it's place. The Redhat rep was very adamant about KVMs superiority over Xen and the amount of unnecessary work to integrate Xen into their kernels. Some day when KVM will actually do what Xen does (and do it reliably!) Xen may not be an easy option. Grant ___ So are you saying we should start looking at using KVM instead? I've never seen it, nor used it, so how much different is it from XEN? -- Kind Regards Rudi Ahlers Check out my technical blog, http://blog.softdux.com for Linux or other technical stuff ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt I personally like Xen even though it's a bit difficult sometimes. The reality is that there probably will be a Linux Virtual Machine and then there will be the other third party ones that you can run if you want to go through the trouble. Xen, VMWare, VBox etc.. are third party. KVM is and will be integrated into the OS and will be everywhere. The amount of work being done on it is frightening. However, I don't think KVM will ever do real paravirtualization as they only focus on CPUs with VT support built in. They do paravirtualize drivers but the rest is roughly equivalent to HVM in Xen. I don't use KVM in any production environment because it's not always stable. I don't use it in a development environment because it doesn't do everything I want. Both of these things will change in the future. Because of the way the KVM VMs are handled (as tasks) though I'm not sure if it will ever be very good at having one VM span multiple real pipelines. But then again I'm not sure how efficient Xen can accomplish this. I'm working on a white paper testing the capabilities and speed of the major VM technologies in various environments but I have several months of testing left before I will release it. I'll know more when I get more data. Grant ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] xen 3.2
On Mon, Jul 14, 2008 at 2:46 PM, Daniel de Kok [EMAIL PROTECTED] wrote: On Mon, Jul 14, 2008 at 5:04 PM, Justin Lim [EMAIL PROTECTED] wrote: Any ideal when 3.2 xen will be avail for centos? When the upstream distribution provides it. I am not sure if it is on their roadmap. Of course, you could also use Xen 3.2 from XenSource, but that's not supported here. Take care, Daniel ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt I was at a recent Linux convention and it seemed very likely that Xen is no longer Redhat's priority at all and would love to put KVM in it's place. The Redhat rep was very adamant about KVMs superiority over Xen and the amount of unnecessary work to integrate Xen into their kernels. Some day when KVM will actually do what Xen does (and do it reliably!) Xen may not be an easy option. Grant ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
