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Re: Problem with pg_compresslog'd archives

From: Koichi Suzuki <koichi(dot)szk(at)gmail(dot)com>
To: Karl Denninger <karl(at)denninger(dot)net>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Problem with pg_compresslog'd archives
Date: 2010-02-11 14:28:00
Message-ID: ef4f49ae1002110628i1fde0491l497e038109671ef0@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-general
I understand the situation.   I'll upload the improved code ASAP.

----------
Koichi Suzuki



2010/2/11 Karl Denninger <karl(at)denninger(dot)net>:
> Will this come through as a commit on the pgfoundry codebase?  I've
> subscribed looking for it....
>
> The last edit, if I read the release notes and tracebacks on the codebase
> correctly, goes back to the early part of 2009 - which strongly implies that
> there are a **LOT** of people out there that could be running this code with
> un-restoreable archives!
>
> That, for obvious reasons, could be VERY, VERY bad if someone was to suffer
> a system crash....
>
>
> Koichi Suzuki wrote:
>
> I found it's pg_compresslog problem (calculation of XNOOP record
> length used in pg_decompresslog).    I'm fixing the bug and will
> upload the fix shortly.
>
> Sorry for inconvenience.
>
> ------------------
> Koichi Suzuki
>
> 2010/2/8 Karl Denninger <karl(at)denninger(dot)net>:
>
>
> This may belong in a bug report, but I'll post it here first...
>
> There appears to be a **SERIOUS** problem with using pg_compresslog and
> pg_uncompresslog with Postgresql 8.4.2.
>
> Here's my configuration snippet:
>
> full_page_writes = on                   # recover from partial page writes
> wal_buffers = 256kB                     # min 32kB
>                                        # (change requires restart)
> #wal_writer_delay = 200ms               # 1-10000 milliseconds
>
> #commit_delay = 0                       # range 0-100000, in microseconds
> #commit_siblings = 5                    # range 1-1000
>
> # - Checkpoints -
>
> checkpoint_segments = 64                # in logfile segments, min 1,
> 16MB each
> #checkpoint_timeout = 5min              # range 30s-1h
> checkpoint_completion_target = 0.9      # checkpoint target duration,
> 0.0 - 1.0
> #checkpoint_warning = 30s               # 0 disables
>
> archive_command = 'test ! -f /dbms/pg_archive/%f.bz2 && pg_compresslog
> %p | bzip2 - >/dbms/pg_archive/%f.bz2'           #command to use to
> archive a logfile segment
>
> All appears to be fine with the writes, and they are being saved off on
> the nightly backups without incident.
>
> I take a full dump using the instructions in the documentation and make
> sure I copy the proper "must have" file for consistency to be reached.
>
> The problem comes when I try to restore.
>
> recovery_conf contains:
>
> restore_command = '/usr/local/pgsql/recovery.sh %f %p'
>
> And that file contains:
>
>
> #! /bin/sh
>
> infile=$1
> outfile=$2
>
> if test -f /dbms/pg_archive/$infile.bz2
> then
>        bunzip2 -c /dbms/pg_archive/$infile.bz2 |
> /usr/local/pgsql/bin/pg_decompresslog - $outfile
>        exit 0
> else
>        exit 1
> fi
>
> ==============
>
> The problem is that it appears that some of the segments being saved are
> no good!  On occasion I get this when trying to restore...
>
> Feb  7 12:43:51 dbms2 postgres[2001]: [210-1] LOG:  restored log file
> "00000001000001710000009A" from archive
> Feb  7 12:43:52 dbms2 postgres[2001]: [211-1] LOG:  restored log file
> "00000001000001710000009B" from archive
> Feb  7 12:43:52 dbms2 postgres[2001]: [212-1] LOG:  restored log file
> "00000001000001710000009C" from archive
> Feb  7 12:43:52 dbms2 postgres[2001]: [213-1] LOG:  restored log file
> "00000001000001710000009D" from archive
> Feb  7 12:43:53 dbms2 postgres[2001]: [214-1] LOG:  restored log file
> "00000001000001710000009E" from archive
> Feb  7 12:43:53 dbms2 postgres[2001]: [215-1] LOG:  restored log file
> "00000001000001710000009F" from archive
> Feb  7 12:43:54 dbms2 postgres[2001]: [216-1] LOG:  restored log file
> "0000000100000171000000A0" from archive
> Feb  7 12:43:54 dbms2 postgres[2001]: [217-1] LOG:  restored log file
> "0000000100000171000000A1" from archive
> Feb  7 12:43:55 dbms2 postgres[2001]: [218-1] LOG:  restored log file
> "0000000100000171000000A2" from archive
> Feb  7 12:43:55 dbms2 postgres[2001]: [219-1] LOG:  restored log file
> "0000000100000171000000A3" from archive
> Feb  7 12:43:56 dbms2 postgres[2001]: [220-1] LOG:  restored log file
> "0000000100000171000000A4" from archive
> Feb  7 12:43:56 dbms2 postgres[2001]: [221-1] LOG:  restored log file
> "0000000100000171000000A5" from archive
> Feb  7 12:43:57 dbms2 postgres[2001]: [222-1] LOG:  restored log file
> "0000000100000171000000A6" from archive
> Feb  7 12:43:57 dbms2 postgres[2001]: [223-1] PANIC:  corrupted page
> pointers: lower = 772, upper = 616, special = 0
> Feb  7 12:43:57 dbms2 postgres[2001]: [223-2] CONTEXT:  xlog redo
> hot_update: rel 1663/616245/1193269; tid 53/93; new 53/4
> Feb  7 12:43:57 dbms2 postgres[2000]: [1-1] LOG:  startup process (PID
> 2001) was terminated by signal 6: Abort trap
> Feb  7 12:43:57 dbms2 postgres[2000]: [2-1] LOG:  terminating any other
> active server processes
>
> Eek.
>
> I assume this means that either A6 or A7 is corrupt.  But I have the
> file both in the restore AND ON THE MACHINE WHERE IT ORIGINATED:
>
> On the SOURCE machine (which is running just fine):
> tickerforum# cksum *171*A[67]*
> 172998591 830621 0000000100000171000000A6.bz2
> 1283345296 1541006 0000000100000171000000A7.bz2
>
> And off the BACKUP archive, which is what I'm trying to restore:
>
> # cksum *171*A[67]*
> 172998591 830621 0000000100000171000000A6.bz2
> 1283345296 1541006 0000000100000171000000A7.bz2
>
> Identical, says the checksums.
>
> This is VERY BAD - if pg_compresslog is damaging the files in some
> instances then ANY BACKUP TAKEN USING THEM IS SUSPECT AND MAY NOT
> RESTORE!!!!!!
>
> Needless to say this is a MAJOR problem.
>
> -- Karl Denninger
>
>
>
> --
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>
>
>
>
>

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