Hello All,
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I am working with a client who is facing issues with database corruption after a physical hard power off (the machines are at remote sites, this could be a power outage or user error).
They have an environment made up of many of the following consumer grade stand alone machines:
- Windows 7 SP1
- PostgreSQL 9.2.4
- Integrated Raid Controller
- Managed by Intel Rapid Storage Technology
- RAID 1 over two disks
- Disk caching disabled
- Not battery backed
- Disk cache disabled
- 2x Seagate SATA disk drives (st500lm021-1kj152)
PostgreSQL is configured as follows:
- fsync=on
- full_page_writes=on
- wal_sync_method=fsync_
writethrough
Windows is configured as follows:
- Disk caching disabled for the RAID1 set
They have currently proven that the corruption is repeatable in a testbed with and without OS/RAID controller caching - but I am working with them to make this process a little more detailed.
The new process will be:
- Power on machine
- If PostgreSQL doesn't start archive $PGDATA and initdb
- Perform a pg_dumpall to test for corruption
- If pg_dumpall fails then archive $PGDATA and initdb
- Start test suite (which mimics high load from their application), which INSERTS and DELETES records in and out of transaction
- After 15 minutes cut power and repeat process
We are hoping to get about 20 machines in this testbed, giving us around 1500 power cycles per day.
Test scenarios which have been floated so far:
- As described above, all caching off
- As described above, all caching off, 9.2 stable
- As described above, all caching off, 9.5 stable with checksums
Can anyone think of anything else we should be considering / testing / factoring in?
Cheers,
James Sewell,
PostgreSQL Team Lead / Solutions Architect
Suite 112, Jones Bay Wharf, 26-32 Pirrama Road, Pyrmont NSW 2009
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