Re: What's better: Raid 0 or disk for seperate pg_xlog

Karim Nassar wrote:

>Thanks to all for the tips.
>
>
...

>>In general I would recommend RAID1, because that is the safe bet. If
>>your db is the bottleneck, and your data isn't all that critical, and
>>you are read heavy, I would probably go with RAID1, if you are write
>>
>>
                                                 ^^^^^ -> RAID0

>>heavy I would say 2 independent disks.
>>
>>
>
>I feel that we have enough data safety such that I want to go for speed.
>Some of the queries are very large joins, and I am going for pure
>throughput at this point - unless someone can find a hole in my backup
>tactic.
>
>Of course, later we will have money to throw at more spindles. But for
>now, I am trying gaze in to the future and maximize my current
>capabilities.
>
>
>Seems to me that the "best" solution would be:
>
>* disk 0 partition 1..n - os mounts
>         partition n+1  - /var/lib/postgres/data/pg_xlog
>
>* disk 1 partition 1    - /var/lib/postgres/data
>
>* Further (safe) performance gains can be had by adding more spindles as
>such:
> - first disk: RAID1 to disk 1
> - next 2 disks: RAID 0 across the above
>
>
Sounds decent to me.
I did make the mistake that you might want to consider a RAID0. But the
performance gains might be small, and you potentially lose everything.
But your update strategy seems dead on.

>Do I grok it?
>
>Thanks again,
>
>

John
=:->