Re: Options for fsync?

A B wrote:
> If I had a controller with battery, then I could use fsync=off, but I
> should still disable the write cache?
>

Never turn fsync=off. Always disable any write cache on the drives
themselves; most good battery-backed RAID controllers will do that for
you. So long as the battery continues to work, you can keep the write
cache on the controller itself enabled, and in fact you have to do so in
order to get good commit performance. Given that eventually all
batteries fail, the better cards on the market actually make that an
explicit setting, which is the safest setting if available: write-back
cache enabled when battery works, write-through [cache disabled] if doesn't.

Make sure you setup monitoring alerts via e-mail for drive and battery
failures too; test them out by yanking at drive before the server goes
into production if you can.

--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us