I would go with tgt regardless of your HA solution. I tried to use LIO for a long time and am glad I finally seriously tested tgt. Two big reasons are
1) latest rbd code will be in tgt 2) two less reasons for a kernel panic in the proxy node (rbd and iscsi) For me, I'm comfortable with how my system is configured with the Active/Passive config. This only because of the network architecture and the fact that I administer the ESXi hosts. I also have separate rbd disks for each environment, so if I do get VMFS corruption, it is isolated to one system. Another thing I forgot is that I disabled all the VAAI accelleration based on this advice when using tgt: http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-May/039670.html I was having poor performance with VAAI turned on and tgt. LIO performed the same with or without VAAI for my workload. I'm not sure if that changes the way VMFS locking works enough to sidestep the issue. I think that I'm falling back to just persistent SCSI reservations instead of ATS. I think I'm still open to corruption for the same reason. See here if you haven't already for more details on VMFS locking: http://blogs.vmware.com/vsphere/2012/05/vmfs-locking-uncovered.html Jake On Friday, January 23, 2015, Nick Fisk <n...@fisk.me.uk> wrote: > Thanks for your responses guys, > > > > I’ve been spending a lot of time looking at this recently and I think I’m > even more confused than when I started. > > > > I been looking at trying to adapt a resource agent made by tiger computing > ( > http://xo4t.mjt.lu/link/xo4t/gv9y7rs/1/7MG13jwJZd0R-D8FrJljFA/aHR0cHM6Ly9naXRodWIuY29tL3RpZ2VyY29tcHV0aW5nL29jZi1saW8) > to create a HA LIO failover target, Instead of going with the Virtual IP > failover method it manipulates the ALUA states to present active/standby > paths. It’s very complicated and am close to giving up. > > > > What do you reckon accept defeat and go with a much simpler tgt and > virtual IP failover solution for time being until the Redhat patches make > their way into the kernel? > > > > *From:* Jake Young [mailto:jak3...@gmail.com > <javascript:_e(%7B%7D,'cvml','jak3...@gmail.com');>] > *Sent:* 23 January 2015 16:46 > *To:* Zoltan Arnold Nagy > *Cc:* Nick Fisk; ceph-users > *Subject:* Re: [ceph-users] Ceph, LIO, VMWARE anyone? > > > > Thanks for the feedback Nick and Zoltan, > > > > I have been seeing periodic kernel panics when I used LIO. It was either > due to LIO or the kernel rbd mapping. I have seen this on Ubuntu precise > with kernel 3.14.14 and again in Ubunty trusty with the utopic kernel > (currently 3.16.0-28). Ironically, this is the primary reason I started > exploring a redundancy solution for my iSCSI proxy node. So, yes, these > crashes have nothing to do with running the Active/Active setup. > > > > I am moving my entire setup from LIO to rbd enabled tgt, which I've found > to be much more stable and gives equivalent performance. > > > > I've been testing active/active LIO since July of 2014 with VMWare and > I've never seen any vmfs corruption. I am now convinced (thanks Nick) that > it is possible. The reason I have not seen any corruption may have to do > with how VMWare happens to be configured. > > > > Originally, I had made a point to use round robin path selection in the > VMware hosts; but as I did performance testing, I found that it actually > didn't help performance. When the host switches iSCSI targets there is a > short "spin up time" for LIO to get to 100% IO capability. Since round > robin switches targets every 30 seconds (60 seconds? I forget), this seemed > to be significant. A secondary goal for me was to end up with a config > that required minimal tuning from VMWare and the target software; so the > obvious choice is to leave VMWare's path selection at the default which is > Fixed and picks the first target in ASCII-betical order. That means I am > actually functioning in Active/Passive mode. > > > > Jake > > > > > > > > > > On Fri, Jan 23, 2015 at 8:46 AM, Zoltan Arnold Nagy < > zol...@linux.vnet.ibm.com > <javascript:_e(%7B%7D,'cvml','zol...@linux.vnet.ibm.com');>> wrote: > > Just to chime in: it will look fine, feel fine, but underneath it's quite > easy to get VMFS corruption. Happened in our tests. > Also if you're running LIO, from time to time expect a kernel panic > (haven't tried with the latest upstream, as I've been using > Ubuntu 14.04 on my "export" hosts for the test, so might have improved...). > > As of now I would not recommend this setup without being aware of the > risks involved. > > There have been a few upstream patches getting the LIO code in better > cluster-aware shape, but no idea if they have been merged > yet. I know RedHat has a guy on this. > > On 01/21/2015 02:40 PM, Nick Fisk wrote: > > Hi Jake, > > > > Thanks for this, I have been going through this and have a pretty good > idea on what you are doing now, however I maybe missing something looking > through your scripts, but I’m still not quite understanding how you are > managing to make sure locking is happening with the ESXi ATS SCSI command. > > > > From this slide > > > > > http://xo4t.mjt.lu/link/xo4t/gv9y7rs/2/nyQ_DOajzbkwqlXJFu3sOw/aHR0cDovL3hvNHQubWp0Lmx1L2xpbmsveG80dC9nenlodHgzLzEvXzlnSlZNVXJTZHZ6R1hZYVpmQ2tWQS9hSFIwY0hNNkx5OTNhV3RwTG1ObGNHZ3VZMjl0TDBCaGNHa3ZaR1ZyYVM5bWFXeGxjeTh6T0M5b1lXMXRaWEl0WTJWd2FDMWtaWFpsYkMxemRXMXRhWFF0YzJOemFTMTBZWEpuWlhRdFkyeDFjM1JsY21sdVp5NXdaR1k > (Page 8) > > > > It seems to indicate that for a true active/active setup the two targets > need to be aware of each other and exchange locking information for it to > work reliably, I’ve also watched the video from the Ceph developer summit > where this is discussed and it seems that Ceph+Kernel need changes to allow > this locking to be pushed back to the RBD layer so it can be shared, from > what I can see browsing through the Linux Git Repo, these patches haven’t > made the mainline kernel yet. > > > > Can you shed any light on this? As tempting as having active/active is, > I’m wary about using the configuration until I understand how the locking > is working and if fringe cases involving multiple ESXi hosts writing to the > same LUN on different targets could spell disaster. > > > > Many thanks, > > Nick > > > > *From:* Jake Young [mailto:jak3...@gmail.com > <javascript:_e(%7B%7D,'cvml','jak3...@gmail.com');>] > *Sent:* 14 January 2015 16:54 > > > *To:* Nick Fisk > *Cc:* Giuseppe Civitella; ceph-users > *Subject:* Re: [ceph-users] Ceph, LIO, VMWARE anyone? > > > > Yes, it's active/active and I found that VMWare can switch from path to > path with no issues or service impact. > > > > > > I posted some config files here: github.com/jak3kaj/misc > <http://xo4t.mjt.lu/link/xo4t/gv9y7rs/3/D81eeuPo8XnPx6ZCQ3g8sw/aHR0cDovL3hvNHQubWp0Lmx1L2xpbmsveG80dC9nenlodHgzLzIvX1AySFdqM1J4UVpDMXY1RFFfMjA2US9hSFIwY0RvdkwyZHBkR2gxWWk1amIyMHZhbUZyTTJ0aGFpOXRhWE5q> > > > > One set is from my LIO nodes, both the primary and secondary configs so > you can see what I needed to make unique. The other set (targets.conf) are > from my tgt nodes. They are both 4 LUN configs. > > > > Like I said in my previous email, there is no performance difference > between LIO and tgt. The only service I'm running on these nodes is a > single iscsi target instance (either LIO or tgt). > > > > Jake > > > > On Wed, Jan 14, 2015 at 8:41 AM, Nick Fisk <n...@fisk.me.uk > <javascript:_e(%7B%7D,'cvml','n...@fisk.me.uk');>> wrote: > > Hi Jake, > > > > I can’t remember the exact details, but it was something to do with a > potential problem when using the pacemaker resource agents. I think it was > to do with a potential hanging issue when one LUN on a shared target failed > and then it tried to kill all the other LUNS to fail the target over to > another host. This then leaves the TCM part of LIO locking the RBD which > also can’t fail over. > > > > That said I did try multiple LUNS on one target as a test and didn’t > experience any problems. > > > > I’m interested in the way you have your setup configured though. Are you > saying you effectively have an active/active configuration with a path > going to either host, or are you failing the iSCSI IP between hosts? If > it’s the former, have you had any problems with scsi > locking/reservations…etc between the two targets? > > > > I can see the advantage to that configuration as you reduce/eliminate a > lot of the troubles I have had with resources failing over. > > > > Nick > > > > *From:* Jake Young [mailto:jak3...@gmail.com > <javascript:_e(%7B%7D,'cvml','jak3...@gmail.com');>] > *Sent:* 14 January 2015 12:50 > *To:* Nick Fisk > *Cc:* Giuseppe Civitella; ceph-users > *Subject:* Re: [ceph-users] Ceph, LIO, VMWARE anyone? > > > > Nick, > > > > Where did you read that having more than 1 LUN per target causes stability > problems? > > > > I am running 4 LUNs per target. > > > > For HA I'm running two linux iscsi target servers that map the same 4 rbd > images. The two targets have the same serial numbers, T10 address, etc. I > copy the primary's config to the backup and change IPs. This way VMWare > thinks they are different target IPs on the same host. This has worked very > well for me. > > > > One suggestion I have is to try using rbd enabled tgt. The performance is > equivalent to LIO, but I found it is much better at recovering from a > cluster outage. I've had LIO lock up the kernel or simply not recognize > that the rbd images are available; where tgt will eventually present the > rbd images again. > > > > I have been slowly adding servers and am expanding my test setup to a > production setup (nice thing about ceph). I now have 6 OSD hosts with 7 > disks on each. I'm using the LSI Nytro cache raid controller, so I don't > have a separate journal and have 40Gb networking. I plan to add another 6 > OSD hosts in another rack in the next 6 months (and then another 6 next > year). I'm doing 3x replication, so I want to end up with 3 racks. > > > > Jake > > On Wednesday, January 14, 2015, Nick Fisk <n...@fisk.me.uk > <javascript:_e(%7B%7D,'cvml','n...@fisk.me.uk');>> wrote: > > Hi Giuseppe, > > > > I am working on something very similar at the moment. I currently have it > working on some test hardware but seems to be working reasonably well. > > > > I say reasonably as I have had a few instability’s but these are on the HA > side, the LIO and RBD side of things have been rock solid so far. The main > problems I have had seem to be around recovering from failure with > resources ending up in a unmanaged state. I’m not currently using fencing > so this may be part of the cause. > > > > As a brief description of my configuration. > > > > 4 Hosts each having 2 OSD’s also running the monitor role > > 3 additional host in a HA cluster which act as iSCSI proxy nodes. > > > > I’m using the IP, RBD, iSCSITarget and iSCSILUN resource agents to provide > HA iSCSI LUN which maps back to a RBD. All the agents for each RBD are in a > group so they follow each other between hosts. > > > > I’m using 1 LUN per target as I read somewhere there are stability > problems using more than 1 LUN per target. > > > > Performance seems ok, I can get about 1.2k random IO’s out the iSCSI LUN. > These seems to be about right for the Ceph cluster size, so I don’t think > the LIO part is causing any significant overhead. > > > > We should be getting our production hardware shortly which wil have 40 > OSD’s with journals and a SSD caching tier, so within the next month or so > I will have a better idea of running it in a production environment and the > performance of the system. > > > > Hope that helps, if you have any questions, please let me know. > > > > Nick > > > > *From:* ceph-users [mailto:ceph-users-boun...@lists.ceph.com > <javascript:_e(%7B%7D,'cvml','ceph-users-boun...@lists.ceph.com');>] *On > Behalf Of *Giuseppe Civitella > *Sent:* 13 January 2015 11:23 > *To:* ceph-users > *Subject:* [ceph-users] Ceph, LIO, VMWARE anyone? > > > > Hi all, > > > > I'm working on a lab setup regarding Ceph serving rbd images as ISCSI > datastores to VMWARE via a LIO box. Is there someone that already did > something similar wanting to share some knowledge? Any production > deployments? What about LIO's HA and luns' performances? > > > > Thanks > > Giuseppe > > > > > > > _______________________________________________ > > ceph-users mailing list > > ceph-users@lists.ceph.com > <javascript:_e(%7B%7D,'cvml','ceph-users@lists.ceph.com');> > > http://xo4t.mjt.lu/link/xo4t/gv9y7rs/4/jc5GVljNXQQJ9odiIzBBeA/aHR0cDovL2xpc3RzLmNlcGguY29tL2xpc3RpbmZvLmNnaS9jZXBoLXVzZXJzLWNlcGguY29t > > > > > >
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