Réf. : Re: NAS, SAN or any alternate solution ?

Thanks a lot Scott.

It seems that we were totally wrong when considering a network storage
solution. I've read your techdoc
http://techdocs.postgresql.org/guides/DiskTuningGuide and found many
interesting remarks.
I think that we will know focus on external Raid systems which seem to be
relativily affordable compared to NAS or SAN (we would have had the budget
for one of these).
As we don't plan to have more than 5 connections (I.E process), we think
SATA drives would fit our requirements. Could this be an issue for an
after crash recovery ?
We also hesitate concerning the raid level to use. We are currently
comparing raid 1+0 and raid 5 but we have no actual idea on which one to
use.

Our priorities are :
1) performance
2) recovery
3) price
4) back-up

It could be nice to have any comments from people who have already set up
a similar platform, giving some precise details of the hardware
configuration :
- brand of the raid device,
- technology used (SCSI/IDE, RAID level ...),
- size of the database, number of disks/size of disks ...

Such a knowledge base may be useful to convince people to migrate to
opensource cheap reliable solutions.
Thanks again.

Benjamin.

"Scott Marlowe" <smarlowe(at)qwest(dot)net>
Envoyé par : pgsql-performance-owner(at)postgresql(dot)org
20/07/2004 10:20

Pour : bsimon(at)loxane(dot)com
cc : pgsql-performance(at)postgresql(dot)org
Objet : Re: [PERFORM] NAS, SAN or any alternate solution ?

On Tue, 2004-07-20 at 01:52, bsimon(at)loxane(dot)com wrote:
> Hi all,
>
> I've been searching the list for a while but couldn't find any
> up-to-date information relating to my problem.
> We have a production server with postgresql on cygwin that currently
> deels with about 200 Gigs of data (1 big IDE drive). We plan to move
> to linux for some reasons I don't have to explain.
> Our aim is also to be able to increase our storage capacity up to
> approximately 1 or 2 terabytes and to speed up our production process.
> As we are a small "microsoft addicted" company , we have some
> difficulties to choose the best configuration that would best meet our
> needs.
> Our production process is based on transaction (mostly huge inserts)
> and disk access is the main bottlle-neck.
>
> Our main concern is hardware related :
>
> Would NAS or SAN be good solutions ? (I've read that NAS uses NFS
> which could slow down the transfer rate ??)
> Has anyone ever tried one of these with postgresql ?

Your best bet would likely be a large external RAID system with lots o
cache. Next would be a fast internal RAID card like the LSI Megaraid
cards, with lots of drives and batter backed cache. Next would be a
SAN, but be careful, there may be issues with some cards and their
drivers under linux, research them well before deciding. NFS is right
out if you want good performance AND reliability.

The cheapest solution that is likely to meet your needs would be the
internal RAID card with battery backed cache.

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