No problem - I'm sure that you have more then enough on your plate without users pestering you with such esoteric problems ;)
As for the I/O subsystem - on the lowest level it's a couple of RAID5 matrices. Then, there is a Windows Server 2008 managing that and some virtual servers (via Hyper-V), including both of the machines that we had the database on (Windows Server 2008 R2 Enterprise and now Ubuntu 12 LTS). I was assured that the matrices have been running rock-solid since the moment they've been setup and didn't exhibit any hardware failures. However, the servers could have been abruptly shut down, for example when it run out of free disk space. While NTFS should recover from something like that, I wonder if there isn't a corner case that would cause some database corruption (like you're suggesting). Thanks for the recover-couchdb script - I'll try to give it a go ASAP. We do have backups, but I don't think they are helpful in this case - the database as a whole is working, we don't have any reports of missing files or not working documents. It would be interesting to inspect the backups to see when and, more interestingly, what happened. You mentioned that the database format is strictly append only, so the corruption shouldn't "move" and the "old"/early parts of the database file shouldn't change? Still, that seems like a really time consuming task, so for now I'll try to give the recovery script a go. Thanks again for your help and best regards, Igor Klimer ________________________________________ Od: Robert Samuel Newson [[email protected]] Wysłano: 23 stycznia 2014 13:52 Do: user Temat: Re: Error during compaction Hi, Sorry, in turn, for not replying sooner. I’m not really sure what to suggest, it does sound like the database file is corrupt, which is quite hard to do with our strictly append only format. The only oddities here are the use of Windows (and, presumably, NTFS?) and the fact that you did hit end of disk. I’ve not observed corruption when hitting end of disk on other OS/FS combinations, though. Do you happen to know any details of your I/O subsystem that might provide a hint? Could any of the disks themselves have suffered block failures that couldn’t be corrected by disk firmware? Bit flips?Would your disk controller lie about fsync() calls? Those questions will help us figure out how the corruption occurs, but it obviously doesn’t help you fix it. For that, beyond hoping you have backups, I suggest trying https://github.com/jhs/recover-couchdb (perhaps Jason can chip in with how likely this is to still work, given the age). If that doesn’t extract all your data, then the only other suggestion I have is to truncate the database file until it can compact, but this necessarily means losing data. Do other developers have other suggestions here? B. On 21 Jan 2014, at 09:08, Igor Klimer <[email protected]> wrote: > Hi, > I'm extremely sorry for not replying sooner, however I was on sick leave last > week. > I've tried your suggestion with an empty .compact file, however the results > seem to be the same... > Log: http://pastebin.com/MJCgGM8C > > Started with an empty ecrepo.couch.compact file (touch ecrepo.couch.compact), > then after about 3 hours, the error was printed in the logs and the > compaction failed: > -rw-r--r-- 1 couchdb couchdb 137502523517 Jan 21 09:51 ecrepo.couch > -rw-r--r-- 1 couchdb couchdb 51692612367 Jan 21 02:07 ecrepo.couch.compact > > There's over 100GB free space available on the disk. > > At least I think I know what the number 51692471440 in log means ;) But I > don't know if there's a way to check which document resides at that position > in file. > > Best regards, > Igor Klimer > > ________________________________________ > Od: Robert Samuel Newson [[email protected]] > Wysłano: 10 stycznia 2014 18:45 > Do: user > Temat: Re: Error during compaction > > Yes, I understood. The empty .compact file will trigger more checking in the > compaction process, I’m hoping it gets us past the problem. > > B. > > On 10 Jan 2014, at 13:34, Igor Klimer <[email protected]> wrote: > >> :) >> Just to clarify - the .compact file is getting created and then the >> compaction fails after some time (an hour or more): >> 1) attempt on Windows with Couchdb 1.2.0 it failed because insufficient disk >> space. The .compact file had at least 10GB, unfortunately, I don't remember >> how much (and whether it was bigger then the one produced in the later >> attempts). There was no free disk space when it failed, so I'm assuming that >> was the cause. >> 2) attempt on Windows with Couchdb 1.2.0 it failed with the error mentioned >> below. The .compact file had around 50GB, there was plenty of free space >> left on the disk. >> 3) attempt on Ubuntu with Couchdb 1.5.0 it failed with the error mentioned >> below. The .compact file had around 50GB, there was plenty of free space >> left on the disk, and judging from the numbers present in the log (ids? node >> numbers?) it failed at the same moment as attempt #2. >> >> Just wanted to make sure we're on the same page :) Do you still want me to >> try it with an empty .compact file? (I can do this only during night hours, >> since I don't want to put too much load on the server during working hours) >> >> Best regards, >> Igor Klimer >> ________________________________________ >> Od: Robert Samuel Newson [[email protected]] >> Wysłano: 10 stycznia 2014 14:03 >> Do: user >> Temat: Re: Error during compaction >> >> Hrm, strike one. Ok. Next thing to try is subtly different. stop couchdb, >> delete the .compact file, but then make a new, empty .compact file (so >> ’touch /path/to/dbname.compact’), start couchdb and compact. >> >> B. >> >> On 10 Jan 2014, at 12:42, Igor Klimer <[email protected]> wrote: >> >>> Yes, I've already done that after the very fist attempt at compaction (the >>> one that failed because of lack of disk space). And it resulted in the >>> second fail (on Windows), then the same on Linux - I always deleted the >>> incomplete (about 50% of the database, around 50GB) .compact file before >>> running the compaction again. So I was always doing compaction from scratch. >>> >>> Best regards, >>> Igor Klimer >>> ________________________________________ >>> Od: Robert Samuel Newson [[email protected]] >>> Wysłano: 10 stycznia 2014 13:08 >>> Do: user >>> Temat: Re: Error during compaction >>> >>> Thanks! that’s very useful. Hitting end of disk certainly feels like a >>> cause here. Since the compaction has never completed, I suggest we redo >>> compaction from scratch. >>> >>> 1) stop couchdb >>> 2) delete (or move aside) the dbname.compact file for this database >>> 3) start couchdb >>> 4) compact the db >>> >>> Whether it works or not, please let us know. >>> >>> B. >>> >>> On 10 Jan 2014, at 08:25, Igor Klimer <[email protected]> wrote: >>> >>>>> Given that you’re at 100Gb and compacting for the first time, can you >>>>> tell us if you were running on older couchdb versions that 1.2.0 between >>>>> db creation and today? >>>> >>>> No, we've been running 1.2.0 from the start (around Oct 2012), then >>>> switched to Ubuntu and 1.5.0. >>>> >>>>> Do you have free disk space? >>>> Yes, there's about 150% of the DB's size worth of free space :) I forgot >>>> to mention ("OK, here we go, the user will confess to some sin he >>>> committed and is ashamed of and is most likely the reason for this >>>> failure") that we've run the compaction once before the error on Windows I >>>> mentioned below, but it failed because of insufficient disk space - so I >>>> double checked before running the compaction again if there's enough >>>> space. Here's the log, if it's any helpful: http://pastebin.com/S1URXN0p >>>> Do you think it could have left the database in some corrupted state? It >>>> seems it failed at a different part then the two next attempts (and, as >>>> far as I understand, compaction is just copying over the database while >>>> pruning the old revisions and deleted documents). >>>> >>>> Thank you for your time and help and best regards, >>>> Igor Klimer >>>> ________________________________________ >>>> Od: Robert Samuel Newson [[email protected]] >>>> Wysłano: 9 stycznia 2014 17:13 >>>> Do: user >>>> Temat: Re: Error during compaction >>>> >>>> Do you have free disk space? >>>> >>>> On 9 Jan 2014, at 15:25, Robert Samuel Newson <[email protected]> wrote: >>>> >>>>> >>>>> Given that you’re at 100Gb and compacting for the first time, can you >>>>> tell us if you were running on older couchdb versions that 1.2.0 between >>>>> db creation and today? >>>>> >>>>> B. >>>>> >>>>> On 9 Jan 2014, at 14:39, Igor Klimer <[email protected]> wrote: >>>>> >>>>>> Hi all, >>>>>> I've stumbled upon a peculiar problem while trying to compact (for the >>>>>> first time) a large(-ish) database (~100GB at that time). At about 50% >>>>>> it failed with this error: http://pastebin.com/qeaZNHMj >>>>>> This is from Windows Server 2008 R2 Enterprise with Couchdb 1.2.0. >>>>>> I figured that it might be a bug in the Windows build (Erlang on >>>>>> Windows? C'mon, that can't be good ;)) or already fixed in a newer >>>>>> version. Some time later we migrated the server to a Linux box running >>>>>> Ubuntu 12.04.3 LTS (GNU/Linux 3.8.0-33-generic x86_64) and update >>>>>> Couchdb to 1.5.0. >>>>>> Unfortunately, the same error occurred: http://pastebin.com/feJWu7bN >>>>>> >>>>>> I've tried wrapping my head around that error, googling it, checking >>>>>> this mail list but to no avail :) So if anyone can give me any pointers >>>>>> as to what might be causing this problem, I'd be very grateful. >>>>>> >>>>>> Best regards, >>>>>> Igor Klimer >>>>>> >>>>>> (sorry for the footer that will probably follow, unfortunately it's >>>>>> added for all outgoing external mail...) >>>>>> >>>>>> >>>>>> >>>>>> ------------------------------- getBACK S.A., ul. Powstańców Śląskich 2-4, 53-333 Wrocław Sad rejestrowy: Sąd Rejonowy dla Wrocławia - Fabrycznej, VI Wydział Gospodarczy KRS. Numer KRS: 0000413997 NIP: 8992733884 REGON: 021829989 Wysokość kapitału zakładowego opłaconego w całości: 4 000 000,00 zł Zamieszczenie powyższych danych identyfikujących getBACK S.A. stosownie do art. 374 par.1 Kodeksu spółek handlowych nie jest równoznaczne z handlowym charakterem dostarczonej do Państwa wiadomości e-mailowej i pozostaje bez wpływu na interpretacje zawartych w niej oświadczeń. Niniejszy e-mail oraz wszelkie załączone do niego pliki są poufne i mogą podlegać ochronie prawnej. Jeżeli nie jest Pan/Pani zamierzonym adresatem powyższej wiadomości, nie może jej Pan/Pani ujawniać, kopiować, dystrybuować, ani tez w żaden inny sposób udostępniać lub wykorzystywać. O błędnym zaadresowaniu wiadomości prosimy niezwłocznie poinformować nadawcę i usunąć wiadomość. This e-mail message may contain confidential and/or privileged information. If you are not the intended recipient (or have received this e-mail in error) please notify the sender immediately and destroy this e-mail. Any unauthorized copying, disclosure or distribution of the material in this e-mail is strictly forbidden.
