On 2/26/07, Jeff Davis <pgsql@xxxxxxxxxxx> wrote:
On Sun, 2007-02-25 at 23:11 +0100, Peter Kovacs wrote:
> A related question:
> Is it sufficient to disable write cache only on the disk where pg_xlog
> is located? Or should write cache be disabled on both disks?
>
When PostgreSQL does a checkpoint, it thinks the data pages before the
checkpoint have successfully made it to disk.
If the write cache holds those data pages, and then loses them, there's
no way for PostgreSQL to recover. So use a battery backed cache or turn
off the write cache.
Sorry for for not being familar with storage techonologies... Does
"battery" here mean battery in the common sense of the word - some
kind of independent power supply? Shouldn't the disk itself be backed
by a battery? As should the entire storage subsystem?
Thanks
Peter
Regards,
Jeff Davis
