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From: Volkan YAZICI on 27 Jul 2010 15:10 On Tue, 27 Jul 2010, Stan Hoeppner <stan(a)hardwarefreak.com> writes: > What write operations were you performing at the time you pulled the plug? > Unless you were writing the superblock it'd be almost impossible to hose the > filesystem to the point it couldn't mount. Were you doing a resize operation > when you pulled the plug? xfs_growfs? As far as recovery, it's automatic > upon mounting the XFS filesystem. What do you mean, precisely, by "couldn't > *recover* the / fs"? Vanilla XFS with noatime,notail like basic mount options. The test was simple, I was just typing "SELECT 1" from a psql command line (this query shouldn't even hit to disk, it just basically returns 1) and unplugged machine. At boot, I dropped to fsck command line. At command prompt, I manually fiddled around with fsck of xfs to recover the unmounted / filesystem, but had no luck. (I also tried recommendations and informative messages supplied by manpages and command outputs/warnings.) Also if you would Google, it shouldn't be hard to spot similar experiences from other people. At NASA, they might have genius technicians; but, IMHO a majority of the linux users would want a filesystem to recover without a prompt from the user. > I'm basically a one man army trying to defeat misinformation WRT XFS > and attempt to educate ppl with the correct information. I am glad -users ml have you; and I'd be really, really appreaciated if somebody having experience and knowledge on fs issues can shed some light to our ignorance. I also support the replacement of default fs with something that is much more recent. From this point of view, XFS is a superior alternative. You are totally right with your claims about its advantages over other alternatives. But as you can see, people still complain about XFS's sensitivity to power failures. Assuming a majority of your users aren't behind a UPS, you can sell/ship your product with such a default filesystem choice. But as you said, there are no published concrete benchmarks about this issue. It is all what people claim in the mailing lists. If you would share some of your findings about "Power Failures and XFS" to convince us, I'm sure most of us will be happy to advocate XFS's this achievement. Regards. -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/87fwz4u4oi.fsf(a)alamut.alborz.net
From: Stan Hoeppner on 27 Jul 2010 16:10 Volkan YAZICI put forth on 7/27/2010 2:04 PM: > unplugged machine. At boot, I dropped to fsck command line. At command Were you forced to the command line or did you manually select to go to the command line? It sounds like you chose to, not forced to. > prompt, I manually fiddled around with fsck of xfs to recover the > unmounted / filesystem, but had no luck. Did you read the xfs documentation before embarking on this power loss experiment? Or did you it "should just work" regardless of your actions, or lack of action? It sounds like you ran xfs_repair on a filesystem in an inconsistent state and forced changes, which is a no-no. (I also tried recommendations > and informative messages supplied by manpages and command > outputs/warnings.) Also if you would Google, it shouldn't be hard to > spot similar experiences from other people. I'm guessing most of them didn't look before taking the XFS leap. > At NASA, they might have genius technicians; but, IMHO a majority of the > linux users would want a filesystem to recover without a prompt from the > user. So the system wouldn't boot and you were dropped to a prompt. You manually fiddled around with fsck of xfs and made no progress. It would be nice to have seen all of that at the time. What were your results when you did this same power yank test with ext2/3, ReiserFS, and the other filesystems you tested in this way? >> I'm basically a one man army trying to defeat misinformation WRT XFS >> and attempt to educate ppl with the correct information. > > I am glad -users ml have you; and I'd be really, really appreaciated if > somebody having experience and knowledge on fs issues can shed some > light to our ignorance. I also support the replacement of default fs > with something that is much more recent. From this point of view, XFS is > a superior alternative. You are totally right with your claims about its > advantages over other alternatives. But as you can see, people still > complain about XFS's sensitivity to power failures. Assuming a majority > of your users aren't behind a UPS, you can sell/ship your product with > such a default filesystem choice. But as you said, there are no > published concrete benchmarks about this issue. It is all what people > claim in the mailing lists. If you would share some of your findings > about "Power Failures and XFS" to convince us, I'm sure most of us will > be happy to advocate XFS's this achievement. I've tried to dig up accurate accounts of the power loss corruption issue post 2007 (when it was supposed to have been fixed) a few times but couldn't find anything concrete enough to be worth referencing. I freely admit I've done no power loss testing of XFS myself. This probably has to do with the fact that I'm a firm believer in orderly shutdowns and redundant power, and that I don't really have any test systems available. I'll ask around on the XFS list and see what folks have to say. I'm somewhat interested in seeing where BTRFS is in 2-3 years. It may be stable enough for production by then, and should be as fast or faster than XFS on some workloads. Maybe it'll even handle sudden power loss gracefully. :) -- Stan -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/4C4F3CE4.2080503(a)hardwarefreak.com
From: Rob Owens on 27 Jul 2010 17:40 On Tue, Jul 27, 2010 at 01:39:18PM -0500, Stan Hoeppner wrote: > Volkan YAZICI put forth on 7/27/2010 12:19 PM: > > > About a year ago, in a similar rush to yours, I ported two of our > > PostgreSQL database servers to XFS. During testing period, I even > > couldn't *recover* the / fs after the very first power failure test. > > What write operations were you performing at the time you pulled the plug? > Unless you were writing the superblock it'd be almost impossible to hose the > filesystem to the point it couldn't mount. Were you doing a resize operation > when you pulled the plug? xfs_growfs? As far as recovery, it's automatic > upon mounting the XFS filesystem. What do you mean, precisely, by "couldn't > *recover* the / fs"? > Some anecdotal evidence in support of ext3's resilience to power loss: I recently lost power while my system was running. When power was restored, an fsck was automatically performed. During that fsck, I lost power again! I thought for sure I'd be hosed, but after the power came back and an fsck completed, everything seems to be working normally. -Rob -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/20100727213610.GA14074(a)aurora.owens.net
From: Stan Hoeppner on 27 Jul 2010 19:40 Rob Owens put forth on 7/27/2010 4:36 PM: > On Tue, Jul 27, 2010 at 01:39:18PM -0500, Stan Hoeppner wrote: >> Volkan YAZICI put forth on 7/27/2010 12:19 PM: >> >>> About a year ago, in a similar rush to yours, I ported two of our >>> PostgreSQL database servers to XFS. During testing period, I even >>> couldn't *recover* the / fs after the very first power failure test. >> >> What write operations were you performing at the time you pulled the plug? >> Unless you were writing the superblock it'd be almost impossible to hose the >> filesystem to the point it couldn't mount. Were you doing a resize operation >> when you pulled the plug? xfs_growfs? As far as recovery, it's automatic >> upon mounting the XFS filesystem. What do you mean, precisely, by "couldn't >> *recover* the / fs"? >> > Some anecdotal evidence in support of ext3's resilience to power loss: > > I recently lost power while my system was running. When power was > restored, an fsck was automatically performed. During that fsck, I lost > power again! I thought for sure I'd be hosed, but after the power came > back and an fsck completed, everything seems to be working normally. If no writes are in process or pending, it really doesn't matter which fs you use, as none of them will suffer negative effects. All will recover after a journal replay or fsck. For journaling filesystems that are configured properly, even if a write is in progress when the power goes out, the filesystem will not be corrupted as a result. You will have lost data, but the filesystem itself will be healthy. This is one of the two main purposes of a journaling filesystem. The other is rapid recovery. You experienced both in your example. :) -- Stan -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/4C4F6E38.9080101(a)hardwarefreak.com
From: Paul E Condon on 27 Jul 2010 22:00
On 20100727_134650, Stan Hoeppner wrote: > Volkan YAZICI put forth on 7/27/2010 12:29 PM: > > > I don't even think Linus is using XFS too. Isn't he a technical person > > Linus uses them all. You should know that. > > > in terms of your definition? So what should we do in that case? Ask to > > RMS? > > kernel.org servers all run XFS as well. > > -- > Stan Stan, Have you ever heard of the term 'invincible ignorance'? It is a term used in Catholic apologesis to describe the state of unbelievers who simply refuse to accept any argument intended to convert them. I suggest that you come to recognize some invincible ignorance here. Also, you have asserted with some vigor upstream, that any computer person who doesn't have UPS on all his/her systems is somehow not really a real computer person. Personally, I am puzzled about a test of XFS on a system running a serious relational database managed using PostgreSQL that does not have UPS. I infer that there was no UPS because if there were, pulling the plug would not have caused any harm, or, knowing that there was a UPS the testers would have not pulled the plug because it would have been a silly 'test'. Your original post in this thread addressed a quite disfunctional attitude of OP, and IMHO, was correct but somewhat harshly worded. In truth, he simply cannot have everything he wants all at the same time. You should have left it at that, IMHO. I suggest that you try to learn to live with the fact that there is a vast unwashed mass of invincibly ignorant people who call themselves computer experts. Unless you relish this heated controversy, you should limit your recommendation of XFS to shops that take for granted the necessity of having UPS first. Peace. -- Paul E Condon pecondon(a)mesanetworks.net -- To UNSUBSCRIBE, email to debian-user-REQUEST(a)lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmaster(a)lists.debian.org Archive: http://lists.debian.org/20100728015343.GA5462(a)big.lan.gnu |