Re: Storage location of temporary files

Tomasz Ostrowski wrote:
> This is wrong. RAID5 is slower than RAID1.
> You should go for RAID1+0 for fast and reliable storage. Or RAID0 for
> even faster but unreliable.
>
I did not find a clear statement about this. I agree that RAID10 would
be better than RAID5, but in some situations RAID5 at least seems to be
faster than RAID1.

If I have 5 disks available, how should I use them to get best
performance without the risk of severe data loss? If I use 4 of the
disks to build a RAID10 then I will have only 1 remaining drive, e.g. to
put the pgsql_tmp directories there. In this scenario I would not have
the WAL on a separate disk.
Or should I use 3 disks to build a RAID5, 1 disk for tempspace and 1
disk for WAL? How important is data integrity for the WAL? If the WAL
disk fails, can this corrupt my data? Or would I just lose the data
after the last checkpoint?
Or maybe I should use 2 disks as RAID1 for the database, 2 disks as
RAID1 for the WAL and the remaining disk for the tempspace?

Regards,
   Christian

--
Deriva GmbH                         Tel.: +49 551 489500-42
Financial IT and Consulting         Fax:  +49 551 489500-91
Hans-Böckler-Straße 2                  http://www.deriva.de
D-37079 Göttingen

Deriva CA Certificate: http://www.deriva.de/deriva-ca.cer