BUG #4089: When available disk space is low pg_stop_backup() fails, as do subsequent recovery attempts.

"John Smith" <sodgodofall@gmail.com> writes:

Steps to reproduce:
-- start with a running PG instance with WAL archiving enabled
-- select pg_start_backup('test');
-- Fill up the disk on which the data directory is present
-- select pg_stop_backup();
-- fails with: ERROR: could not write file
"pg_xlog/000000010000000000000000.004989E8.backup": No space left on device
-- at this point there is a 0-byte file
pg_xlog/000000010000000000000000.004989E8.backup present on disk
-- stop and start PG
-- recovery fails with: FATAL: invalid data in file
"000000010000000000000000.004989E8.backup"
-- NOTE: At this point removing 000000010000000000000000.004989E8.backup
allows PG to start successfully

What do you see as the bug here? Seems like reasonable behavior to me.

regards, tom lane

On Fri, Apr 4, 2008 at 7:46 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:

"John Smith" <sodgodofall@gmail.com> writes:

Steps to reproduce:
-- start with a running PG instance with WAL archiving enabled
-- select pg_start_backup('test');
-- Fill up the disk on which the data directory is present
-- select pg_stop_backup();
-- fails with: ERROR: could not write file
"pg_xlog/000000010000000000000000.004989E8.backup": No space left on device
-- at this point there is a 0-byte file
pg_xlog/000000010000000000000000.004989E8.backup present on disk
-- stop and start PG
-- recovery fails with: FATAL: invalid data in file
"000000010000000000000000.004989E8.backup"
-- NOTE: At this point removing 000000010000000000000000.004989E8.backup
allows PG to start successfully

What do you see as the bug here? Seems like reasonable behavior to me.

regards, tom lane

I was expecting one of two things:
1. The zero-byte file is removed upon failure to write during
pg_stop_backup() (or )
2. The zero-byte file is ignored or deleted on startup, since the
administrator has no choice but to delete the file upon a failed
startup.

- John