Re: Softupdates question
On Wed, May 09, 2007 at 12:03:40PM -0400, Peter Fraser wrote: I did read the papers. There is a difference between the file system being screwed and data lost. Softupdates hopefully stops the files system from being in a bad state, but it is amazing how much user data can be lost on a power failure while using softupdates. you can loose much more data w/o softdeps _and_ get your filesystem horribly broken. cu -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of mickey Sent: Wednesday, May 09, 2007 11:49 AM To: Peter Fraser Cc: misc@openbsd.org Subject: Re: Softupdates question On Wed, May 09, 2007 at 10:45:15AM -0400, Peter Fraser wrote: I had always assumed the use of softupdates was safe as long as you could have reasonable assurances that the machine would not be shutdown without warning. (i.e. no loss of power or reset being hit). So if you had a UPS, good hardware, and no vandals it's good to use. actually if you bother to read the papers whole idea behind softdeps is to ensure better recoverability from crashes/power/etc. cu -- paranoic mickey (my employers have changed but, the name has remained) -- paranoic mickey (my employers have changed but, the name has remained)
Re: Softupdates question
Still curious how they would work on, say, /var/mysql or /var/postgresql, but I can play with this on my own. Has anyone already tried? Care to comment? FWIW I run softdep on ALL partitions except / and /var and have for many years. I exclude /var because on a crash I want the best chance items logged in /var/log/ to show up. // marc
Re: Softupdates question
mickey wrote: On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: ... Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? If your app makes assumptions about write ordering, softdeps can negate the care the app author took. For example, some mail programs don't ack the receipt of a message until it has been safely written to disk, the idea being that if the power goes out or the machine crashes, if the message has been acknowledged, IT HAS BEEN RECEIVED and will be there when the machine comes back up. Softdeps promises that what is on your disk is coherent, but coherent usually means the last few files written to disk may be just removed when the system comes back up. Not desired in this case. this is not true. fsync() works as specified. Apparently, not all apps use fsync, or don't use it properly. At least qmail advises against the use of softdeps: http://cr.yp.to/qmail/faq/reliability.html#filesystems I also found a reference to another mail program which had people making similar advisories, but not sure if they are still applicable. Softdeps don't do anything for you if you are mostly reading from disk, or if the partition is mounted read-only. It's about writing. of course they do. there are still atime updates for example that will be handled if not mount read-only. yeah, no idea why I phrased it in such absolute terms. duh. Softdeps is much more complex than conventional disk access. While I have not personally seen a softdep-related bug in some time, and that one was quickly fixed, you HAVE to assume it is more likely to have bugs than the non-softdep systems. this is also not exactly true -- there are softdep bugs fixed at the rate of ten per year if not more. most of them are bugs that been there forever. I (apparently) phrased this poorly, having seen at least two unintended interpretations... I have only *experienced* one softdep bug in many years of using it on virtually all partitions of virtually all systems I have installed. After providing the PS and TRACE, I think Pedro had me a patch within an hour. :) Yes, certainly, bugs have been spotted, and there are most likely other bugs that remain. Some people have apps which expose bugs better than mine... If it was not obvious from my comments, I love softdeps. I have a siteXX.tgz file which does a few simple things, one of which is to change all mount points to use softdeps. One really does have to hunt a bit for relevant reasons not to use it. About the only place I can think of where I deliberately don't use it is on an e-mail archive system on the filled partitions which are mounted read-only. I can't tell you how many times I have forgot to install my siteXX file, started loading up /usr/src, and realized, Dang, obviously no softdeps. At which point, I stop the checkout, fix the problem, reboot, and try again. Yes, the performance difference is that obvious, and it is faster to reboot than it is to wait it out. Nick.
Re: Softupdates question
On Wed, May 09, 2007 at 06:46:19AM -0400, Nick Holland wrote: mickey wrote: On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: ... Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? If your app makes assumptions about write ordering, softdeps can negate the care the app author took. For example, some mail programs don't ack the receipt of a message until it has been safely written to disk, the idea being that if the power goes out or the machine crashes, if the message has been acknowledged, IT HAS BEEN RECEIVED and will be there when the machine comes back up. Softdeps promises that what is on your disk is coherent, but coherent usually means the last few files written to disk may be just removed when the system comes back up. Not desired in this case. this is not true. fsync() works as specified. Apparently, not all apps use fsync, or don't use it properly. oh so now you are saying that softdeps are broken because applications are not calling fsync() ? At least qmail advises against the use of softdeps: http://cr.yp.to/qmail/faq/reliability.html#filesystems I also found a reference to another mail program which had people making similar advisories, but not sure if they are still applicable. you whole above statement is wrong and is not based on facts. now you are trying to back it up w/ somebody elses opinion that is also not based on facts. now it is also in the archives and peoples will refer to it as some sort of truth. the damage has been done. cu -- paranoic mickey (my employers have changed but, the name has remained)
Re: Softupdates question
* mickey [EMAIL PROTECTED] [2007-05-09 15:15]: On Wed, May 09, 2007 at 06:46:19AM -0400, Nick Holland wrote: mickey wrote: On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: ... Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? If your app makes assumptions about write ordering, softdeps can negate the care the app author took. For example, some mail programs don't ack the receipt of a message until it has been safely written to disk, the idea being that if the power goes out or the machine crashes, if the message has been acknowledged, IT HAS BEEN RECEIVED and will be there when the machine comes back up. Softdeps promises that what is on your disk is coherent, but coherent usually means the last few files written to disk may be just removed when the system comes back up. Not desired in this case. this is not true. fsync() works as specified. Apparently, not all apps use fsync, or don't use it properly. oh so now you are saying that softdeps are broken because applications are not calling fsync() ? Nick never said softdeps were broken. he said that using them with certain applications is not a good idea - that is different. The application is to blame tho. At least qmail advises against the use of softdeps: http://cr.yp.to/qmail/faq/reliability.html#filesystems I also found a reference to another mail program which had people making similar advisories, but not sure if they are still applicable. you whole above statement is wrong and is not based on facts. now you are trying to back it up w/ somebody elses opinion that is also not based on facts. now it is also in the archives and peoples will refer to it as some sort of truth. the damage has been done. the softdeps are incompatible with qmail truth is as old as softdeps, the damage is long done. -- Henning Brauer, [EMAIL PROTECTED], [EMAIL PROTECTED] BS Web Services, http://bsws.de Full-Service ISP - Secure Hosting, Mail and DNS Services Dedicated Servers, Rootservers, Application Hosting - Hamburg Amsterdam
Re: Softupdates question
I had always assumed the use of softupdates was safe as long as you could have reasonable assurances that the machine would not be shutdown without warning. (i.e. no loss of power or reset being hit). So if you had a UPS, good hardware, and no vandals it's good to use.
Re: Softupdates question
Well, which would you prefer, Peter? I've had systems that have had their power yanked from them several times now, and I've yet to have seen a screwed filesystem. Yes, files created or deleted with 30(?) seconds of the outage might be inconsisten or whatever, I'll take that any day over a damaged filesystem. I think there are bugs in the softdep code. I know of one really busy system that has crashed because of softdeps being on, but only one and I've never been able to pin it down. I would say it works well and gets better with each release. --STeve Andre' On Wednesday 09 May 2007 12:03:40 Peter Fraser wrote: I did read the papers. There is a difference between the file system being screwed and data lost. Softupdates hopefully stops the files system from being in a bad state, but it is amazing how much user data can be lost on a power failure while using softupdates. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of mickey Sent: Wednesday, May 09, 2007 11:49 AM To: Peter Fraser Cc: misc@openbsd.org Subject: Re: Softupdates question On Wed, May 09, 2007 at 10:45:15AM -0400, Peter Fraser wrote: I had always assumed the use of softupdates was safe as long as you could have reasonable assurances that the machine would not be shutdown without warning. (i.e. no loss of power or reset being hit). So if you had a UPS, good hardware, and no vandals it's good to use. actually if you bother to read the papers whole idea behind softdeps is to ensure better recoverability from crashes/power/etc. cu -- paranoic mickey (my employers have changed but, the name has remained)
Re: Softupdates question
On 5/9/07, Nick Holland [EMAIL PROTECTED] wrote: If it was not obvious from my comments, I love softdeps. I have a siteXX.tgz file which does a few simple things, one of which is to change all mount points to use softdeps. One really does have to hunt a bit for relevant reasons not to use it. About the only place I can think of where I deliberately don't use it is on an e-mail archive system on the filled partitions which are mounted read-only. I can't tell you how many times I have forgot to install my siteXX file, started loading up /usr/src, and realized, Dang, obviously no softdeps. At which point, I stop the checkout, fix the problem, reboot, and try again. Yes, the performance difference is that obvious, and it is faster to reboot than it is to wait it out. I'm still curious about the issue of using softdep's when you have a raid card with write-cache (and battery)... I thought I'd do a simple test unpacking the ports.tar.gz with softdeps disabled/enabled, to see for myself. Without softdep enabled, I have the following: [EMAIL PROTECTED] time tar xzf ports.tar.gz 0.970u 2.120s 1:00.62 5.0% 0+0k 9821+210784io 6pf+0w [EMAIL PROTECTED] time rm -r ports 0.160u 1.390s 1:01.65 2.5% 0+0k 14994+126181io 17pf+0w About a minute to unpack and another minute to remove. With softdep enabled, I have the following: [EMAIL PROTECTED] time tar xzf ports.tar.gz 1.270u 2.100s 0:45.62 7.3% 0+0k 9874+66318io 59pf+0w [EMAIL PROTECTED] time rm -r ports 0.210u 1.230s 0:14.59 9.8% 0+0k 15741+22055io 17pf+0w 45 seconds to unpack and 15 seconds to remove. (I've repeated this a few times each way, and I always have roughly the same results.) With softdep enabled, there was more cpu time, but a noticeable decrease in total time. So, fair to say that even with raid+write-cache+battery that softdep's are beneficial (in terms of less disk time)? I'm more interested in maintaining disk-consistency, and with this setup, it looks like softdeps will still help with that also. Thanks again for all the info! -George
Softupdates question
I've just stumbled across the SoftUpdates section in the FAQ, and was rather surprised that I had never seen/heard of this feature before. Before I mount any partition using softdep, I thought I'd google, browse the archives, etc. for any information about when/where they should be used. Although I've found a plethora of information about soft updates, much of it is either contradictory or incomplete I thought I'd ask here for clarification. Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? I have a few machines running a busy website (mounted on /var/www) and two fairly-busy databases (mysql mounted on /var/www and postgresql mounted on /var/postgresql). All these machines have a perc5 raid controller using mfi driver does that make a difference? Running 4.1 MP + patches on all machines (just got the CDs and it's awesome!)...dmesg below. -George p.s. Thanks for the new release! I'm already enjoying it! (and the poster!) OpenBSD 4.1 (GENERIC.MP) #2: Sun May 6 18:14:39 EDT 2007 [EMAIL PROTECTED]:/usr/src/sys/arch/i386/compile/GENERIC.MP cpu0: Intel(R) Xeon(R) CPU 5130 @ 2.00GHz (GenuineIntel 686-class) 2 GHz cpu0: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,TM2,CX16,xTPR real mem = 2146697216 (2096384K) avail mem = 1951940608 (1906192K) using 4278 buffers containing 107458560 bytes (104940K) of memory mainbus0 (root) bios0 at mainbus0: AT/286+ BIOS, date 10/18/06, BIOS32 rev. 0 @ 0xffe90, SMBIOS rev. 2.4 @ 0x7ffbc000 (62 entries) bios0: Dell Inc. PowerEdge 2900 pcibios0 at bios0: rev 2.1 @ 0xf/0x1 pcibios0: PCI IRQ Routing Table rev 1.0 @ 0xfada0/432 (25 entries) pcibios0: PCI Interrupt Router at 000:31:0 (Intel 6321ESB LPC rev 0x00) pcibios0: PCI bus #16 is the last bus bios0: ROM list: 0xc/0x9000! 0xc9000/0x1000 0xca000/0x1800 0xcb800/0x5200 0xec000/0x4000! acpi at mainbus0 not configured ipmi0 at mainbus0: version 2.0 interface KCS iobase 0xca8/8 spacing 4 mainbus0: Intel MP Specification (Version 1.4) cpu0 at mainbus0: apid 0 (boot processor) cpu0: apic clock running at 332 MHz cpu1 at mainbus0: apid 1 (application processor) cpu1: Intel(R) Xeon(R) CPU 5130 @ 2.00GHz (GenuineIntel 686-class) 2 GHz cpu1: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,TM2,CX16,xTPR cpu2 at mainbus0: apid 6 (application processor) cpu2: Intel(R) Xeon(R) CPU 5130 @ 2.00GHz (GenuineIntel 686-class) 2 GHz cpu2: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,TM2,CX16,xTPR cpu3 at mainbus0: apid 7 (application processor) cpu3: Intel(R) Xeon(R) CPU 5130 @ 2.00GHz (GenuineIntel 686-class) 2 GHz cpu3: FPU,V86,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CFLUSH,DS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,SBF,SSE3,MWAIT,DS-CPL,VMX,TM2,CX16,xTPR mainbus0: bus 0 is type PCI mainbus0: bus 1 is type PCI mainbus0: bus 2 is type PCI mainbus0: bus 3 is type PCI mainbus0: bus 4 is type PCI mainbus0: bus 5 is type PCI mainbus0: bus 6 is type PCI mainbus0: bus 7 is type PCI mainbus0: bus 8 is type PCI mainbus0: bus 9 is type PCI mainbus0: bus 10 is type PCI mainbus0: bus 11 is type PCI mainbus0: bus 12 is type PCI mainbus0: bus 13 is type PCI mainbus0: bus 14 is type PCI mainbus0: bus 15 is type PCI mainbus0: bus 16 is type PCI mainbus0: bus 17 is type ISA ioapic0 at mainbus0: apid 8 pa 0xfec0, version 20, 24 pins ioapic0: misconfigured as apic 0, remapped to apid 8 ioapic1 at mainbus0: apid 9 pa 0xfec8, version 20, 24 pins ioapic1: misconfigured as apic 0, remapped to apid 9 ioapic2 at mainbus0: apid 10 pa 0xfec83000, version 20, 24 pins ioapic2: misconfigured as apic 0, remapped to apid 10 pci0 at mainbus0 bus 0: configuration mode 1 (no bios) pchb0 at pci0 dev 0 function 0 Intel 5000X Host rev 0x12 ppb0 at pci0 dev 2 function 0 Intel 5000 PCIE rev 0x12 pci1 at ppb0 bus 6 ppb1 at pci1 dev 0 function 0 Intel 6321ESB PCIE rev 0x01 pci2 at ppb1 bus 7 ppb2 at pci2 dev 0 function 0 Intel 6321ESB PCIE rev 0x01 pci3 at ppb2 bus 8 ppb3 at pci3 dev 0 function 0 ServerWorks PCIE-PCIX rev 0xc2 pci4 at ppb3 bus 9 bnx0 at pci4 dev 0 function 0 Broadcom BCM5708 rev 0x11: apic 8 int 16 (irq 5) ppb4 at pci2 dev 1 function 0 Intel 6321ESB PCIE rev 0x01 pci5 at ppb4 bus 10 ppb5 at pci1 dev 0 function 3 Intel 6321ESB PCIE-PCIX rev 0x01 pci6 at ppb5 bus 11 ral0 at pci6 dev 2 function 0 Ralink RT2561S rev 0x00: apic 9 int 4 (irq 5), address 00:0e:2e:8d:26:66 ral0: MAC/BBP RT2561C, RF RT2527 ppb6 at pci0 dev 3 function 0 Intel 5000 PCIE rev 0x12 pci7 at ppb6 bus 12 ppb7 at pci0 dev 4 function 0 Intel 5000 PCIE rev 0x12 pci8 at ppb7 bus 13 ppb8 at pci0 dev 5 function 0 Intel 5000 PCIE rev 0x12 pci9 at ppb8 bus 1 ppb9 at pci9 dev 0 function 0 Intel
Re: Softupdates question
George C wrote: I've just stumbled across the SoftUpdates section in the FAQ, and was rather surprised that I had never seen/heard of this feature before. Before I mount any partition using softdep, I thought I'd google, browse the archives, etc. for any information about when/where they should be used. Although I've found a plethora of information about soft updates, much of it is either contradictory or incomplete I thought I'd ask here for clarification. Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? Softdep uses more RAM, so if you are on the edge, you might not want it. If you usually run your disks near full capacity, you might have funny results: Assume 100M space free on your disk now. write 90M to the disk delete 90M of other files immediately write 90M more to the disk this 'should' work...but if done quickly with softdeps, it may not, as the deletion may not yet have taken place, and your app may run out of disk space, die with an error message indicating such, but when you look a minute later, there's plenty of space. If your app makes assumptions about write ordering, softdeps can negate the care the app author took. For example, some mail programs don't ack the receipt of a message until it has been safely written to disk, the idea being that if the power goes out or the machine crashes, if the message has been acknowledged, IT HAS BEEN RECEIVED and will be there when the machine comes back up. Softdeps promises that what is on your disk is coherent, but coherent usually means the last few files written to disk may be just removed when the system comes back up. Not desired in this case. Softdeps don't do anything for you if you are mostly reading from disk, or if the partition is mounted read-only. It's about writing. Softdeps rock if you are writing lots of tiny files. For example, unpack the ports tar file on a partition mounted with softdeps and without... or delete the ports tree with softdeps and without. We aren't talking 10% improvements here, we are talking about MANY TIMES the performance. Softdeps is much more complex than conventional disk access. While I have not personally seen a softdep-related bug in some time, and that one was quickly fixed, you HAVE to assume it is more likely to have bugs than the non-softdep systems. Don't get me wrong, for the vast majority of people, softdeps is Just Better, and has been seriously considered to be made the default, but it isn't quite a universal answer. I have a few machines running a busy website (mounted on /var/www) and two fairly-busy databases (mysql mounted on /var/www and postgresql mounted on /var/postgresql). All these machines have a perc5 raid controller using mfi driver does that make a difference? yes... IF the RAID card has a write cache, SOME of the advantage of softdeps may not exist. On the other hand, if it doesn't have the battery, your write performance is so horrible, you probably want softdeps badly. If your busy website and database is read-mostly, softdeps won't help. Nick.
Re: Softupdates question
On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: I've just stumbled across the SoftUpdates section in the FAQ, and was rather surprised that I had never seen/heard of this feature before. Before I mount any partition using softdep, I thought I'd google, browse the archives, etc. for any information about when/where they should be used. Although I've found a plethora of information about soft updates, much of it is either contradictory or incomplete I thought I'd ask here for clarification. Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? If your app makes assumptions about write ordering, softdeps can negate the care the app author took. For example, some mail programs don't ack the receipt of a message until it has been safely written to disk, the idea being that if the power goes out or the machine crashes, if the message has been acknowledged, IT HAS BEEN RECEIVED and will be there when the machine comes back up. Softdeps promises that what is on your disk is coherent, but coherent usually means the last few files written to disk may be just removed when the system comes back up. Not desired in this case. this is not true. fsync() works as specified. Softdeps don't do anything for you if you are mostly reading from disk, or if the partition is mounted read-only. It's about writing. of course they do. there are still atime updates for example that will be handled if not mount read-only. Softdeps is much more complex than conventional disk access. While I have not personally seen a softdep-related bug in some time, and that one was quickly fixed, you HAVE to assume it is more likely to have bugs than the non-softdep systems. this is also not exactly true -- there are softdep bugs fixed at the rate of ten per year if not more. most of them are bugs that been there forever. cu -- paranoic mickey (my employers have changed but, the name has remained)
Re: Softupdates question
Nick Holland wrote: If your busy website and database is read-mostly, softdeps won't help. Even if you do mount a special partition for the logs only of httpd and mount it softdep? On a busy site the logs are growing pretty fast at times and can hold back some processing no?
Re: Softupdates question
mickey wrote: On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: Softdeps don't do anything for you if you are mostly reading from disk, or if the partition is mounted read-only. It's about writing. of course they do. there are still atime updates for example that will be handled if not mount read-only. I find it more efficient to mount a special partition here as well with noatime on it to address that. It's it better? Mounting that partition read only would restrict the changes to the site no? /dev/wd1a /var/www/sites ffs rw,noatime,nodev,nosuid 1 2 Unless you can have two different mount point to the same partition? Never tried it and always assume it wouldn't be possible anyway. Like: /dev/wd1a /var/www/sites ffs rw,nodev,nosuid 1 2 /dev/wd1a /var/www/siteswrite ffs rw,nodev,nosuid 1 2 Can this be done and if so, any drawback to it? So, you configure httpd.conf to use the /var/www/sites, the logs portion of httpd to use /var/www/sites/logs mounted softdep and then /var/www/siteswrite for you to use to change the files on the sites? I don't know, does it really make sense?
Re: Softupdates question
Hi Daniel, Daniel Ouellet wrote on Tue, May 08, 2007 at 03:06:36PM -0400: Unless you can have two different mount point to the same partition? Never tried it and always assume it wouldn't be possible anyway. Then do not guess, but just try it! Some things are really easy to try out... ;-) [EMAIL PROTECTED] # mount | grep tmp /dev/wd0e on /tmp type ffs (local, nodev, nosuid) [EMAIL PROTECTED] # ls -ald /mnt drwxr-xr-x 2 root wheel 512 Apr 3 19:24 /mnt [EMAIL PROTECTED] # mount /dev/wd0e /mnt mount_ffs: /dev/wd0e on /mnt: Device busy [EMAIL PROTECTED] # mount -r /dev/wd0e /mnt mount_ffs: /dev/wd0e on /mnt: Device busy [...] I don't know, does it really make sense? No, it does not, apparently.
Re: Softupdates question
On 5/8/07, mickey [EMAIL PROTECTED] wrote: On Tue, May 08, 2007 at 07:06:06AM -0400, Nick Holland wrote: George C wrote: I've just stumbled across the SoftUpdates section in the FAQ, and was rather surprised that I had never seen/heard of this feature before. Before I mount any partition using softdep, I thought I'd google, browse the archives, etc. for any information about when/where they should be used. Although I've found a plethora of information about soft updates, much of it is either contradictory or incomplete I thought I'd ask here for clarification. Is it always best to mount /, /tmp, /usr, /var, /home with softdep? Under what curcumstances would it not be appropriate? Softdeps don't do anything for you if you are mostly reading from disk, or if the partition is mounted read-only. It's about writing. of course they do. there are still atime updates for example that will be handled if not mount read-only. So, given the above two comments... sounds like softdep would be both safe and beneficial for (at least) /usr and /var. Probably also for /var/www. Still curious how they would work on, say, /var/mysql or /var/postgresql, but I can play with this on my own. Has anyone already tried? Care to comment? All these machines have a perc5 raid controller using mfi driver does that make a difference? yes... IF the RAID card has a write cache, SOME of the advantage of softdeps may not exist. On the other hand, if it doesn't have the battery, your write performance is so horrible, you probably want softdeps badly. Hmm. My cards do have a write cache w/ battery. So in this case, it looks like softdep on any partition would be inappropriateis that correct? Is this simply because the raid card (with write cache) is basically doing what softdep does? Many Thanks for all the advice! -George
