Re: pg_xlog safety

On Tue, Jan 21, 2003 at 03:43:40PM -0500, Vivek Khera wrote:

> So this leads me to my question: one of the tips for performance is to
> move the pg_xlog to its own disk. Now that I have a spare disk I was
> considering moving pg_xlog there. However, that's the only disk that

Test this first. On our Sun A5200 arrays, configured using Veritas
and RAID 1+0, I have tried several times and failed to discover a
performance andvantage by putting the WAL on another disk or pair of
disks. (In other configurations, the same is not the case.)

> wouldn't be RAID protected. What would happen to the db if that disk
> failed? If I were able to perform a clean shutdown, replace that
> disk, and start up postgres again, would it be ok with the pg_xlog
> directory empty? Is it only used for startup after an unclean
> shutdown or for every startup?

I believe you'd need to run pg_resetxlog in this case.

A

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