Horton

Re: Hot Backup with rsync fails at pg_clog if under load

Simon Riggs <simon@2ndquadrant.com>

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From: Simon Riggs <simon@2ndQuadrant.com>
To: Florian Pflug <fgp@phlo.org>
Cc: Daniel Farina <daniel@heroku.com>, Chris Redekop <chris@replicon.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2011-10-26T11:43:07Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Derive oldestActiveXid at correct time for Hot Standby.

  2. Start Hot Standby faster when initial snapshot is incomplete.

  3. Fix timing of Startup CLOG and MultiXact during Hot Standby

On Wed, Oct 26, 2011 at 12:16 PM, Florian Pflug <fgp@phlo.org> wrote:

>> Chris' clog error was caused by a file read error. The file was
>> opened, we did a seek within the file and then the call to read()
>> failed to return a complete page from the file.
>>
>> The xid shown is 22811359, which is the nextxid in the control file.
>>
>> So StartupClog() must have failed trying to read the clog page from disk.
>
> Yep.
>
>> That isn't a Hot Standby problem, a recovery problem nor is it certain
>> its a PostgreSQL problem.
>
> It's very likely that it's a PostgreSQL problem, though. It's probably
> not a pilot error since it happens even for backups taken with pg_basebackup(),
> so the only explanation other than a PostgreSQL bug is broken hardware or
> a pretty serious kernel/filesystem bug.

The way forwards here is for someone to show the clog file that causes
the error and find out why the call to read() fails.

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
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