[ale] Postgresql archive logs

[Jim Kinney]

If the load is heavy write, put wal logs on separate spindles. I've not seen
a performance gain from inode data flip using the same drives space as the
db for wal.
Hmm. Need to send that to the postgres gurus. Use wal as scratch and commit
is a single inode change.

Ok. If the writes are frequent but small, think less than a full 6 disk
stripe, keep it all together. The system can read out of order during the
write flush and speed through on commit.
On Oct 27, 2011 11:56 AM, "Lightner, Jeff" <JLightner at water.com> wrote:

>   Question:****
>
> ** **
>
> For large (~1 TB) Postgresql DB is it better to have archive logs on same
> RAID set as the DB to maximize spindles for the DB or to setup two separate
> RAID sets thereby reducing spindles for the DB?****
>
> ** **
>
> We currently have a Dell PowerEdge with PERC (LSI OEM) RAID Controller.
> Initially it was setup with all 6 internal disks in the same RAID5 set.
> ****
>
> ** **
>
> Our DBAs believe that having archive logs on same disks as DB is a problem
> so want us to redo the layout so that we have 1 x 2 disk mirror for the OS
> and archive longs and a 1 x 4 disk RAID 5 for the DB.   This effectively
> reduces the spindles for DB from 6 to 4.   I’m wondering if the performance
> implications of such a reduction would outweigh the data integrity setup.*
> ***
>
> ** **
>
> Please do NOT suggest installing more disks, or attaching to an external
> array.   These aren’t options for this system.   Also please don’t talk
> about the importance of doing backups I already know that.   Finally don’t
> talk about whether RAID 5 is a good idea – I already know the pitfalls.   My
> questions is not to talk about how it could be done better with
> more/different equipment but rather what is best with the equipment
> described above.****
>
>
>
>
>
>
>
>
>
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