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

Simon Riggs <simon@2ndquadrant.com>

From: Simon Riggs <simon@2ndQuadrant.com>

To: Chris Redekop <chris@replicon.com>

Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2011-10-23T23:27:40Z

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 →

Derive oldestActiveXid at correct time for Hot Standby.
- 656bba95af39 9.0.6 cited
Start Hot Standby faster when initial snapshot is incomplete.
- ff8451aa14c8 9.0.6 cited
Fix timing of Startup CLOG and MultiXact during Hot Standby
- 2f55c535e1f0 9.0.6 cited

On Sun, Oct 16, 2011 at 2:33 AM, Chris Redekop <chris@replicon.com> wrote:

> pg_subtrans: http://pastebin.com/qAXEHAQt

I confirm this as a HS issue and will investigate from here.

FATAL:  could not access status of transaction 21110784
which, in pg_subtrans, is the first xid on a new subtrans page. So we
have missed zeroing a page.

pg_control shows ... Latest checkpoint's oldestActiveXID:  21116666
which shows quite clearly that the pg_control file is later than it should be.

Chris, can you rearrange the backup so you copy the pg_control file as
the first act after the pg_start_backup?

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services