Re: PostgreSQL and SAN/NAS technologies - Mailing list pgsql-general

Hi,

i have seen both mysql and postgresql running on Network Aplliance
Filer via NFS (UNIX/BSD Server). NFS is slower than SAN or local Disks,
with NFS it is easier to move Data from one server to another server.
NFS tuning is tricky, "Netapp NFS" with snaphosts are great. But if
you have a lot of write access I would recommend SAN or local Disks
with RAID (they are much cheaper). If you are using SAN or NAS you should
have a good network and the SAN or NAS should be clustered.

Your opteron system is this a HP DL 385 ?
There you can use up to six 300 GByte SCSI Disk with a RAID Controller(with
up to 192 MB Cache)
and it would be normally the cheapest solution.

-Franz

-----Ursprüngliche Nachricht-----
Von: Mark Cave-Ayland [mailto:m.cave-ayland@webbased.co.uk]
Gesendet: Montag, 28. November 2005 11:31
An: pgsql-general@postgresql.org
Betreff: [GENERAL] PostgreSQL and SAN/NAS technologies


Hi everyone,

We're looking at investing in a new storage system in order to run
PostgreSQL and the advice we are getting is to move away from our current
SAN solution to a NAS solution. Can anyone offer any advice/experience on
using NAS devices to run a PostgreSQL database?

I have seen posts on the lists suggesting that NFS could not offer the
correct semantics to ensure database consistency in terms of flushing data
to disk, but the pre-sales technical team insist it can, even though I
pointed out on their demo system that even MS-SQL server won't install its
data directory on the NAS without a special driver. So have there been any
improvements in the NFS protocol that would make this the case? I suspect
not, but thought I would ask on the list to make sure.

Secondly, we currently run the database over 1Gb fibre. Assuming that NFS is
a no-go, the other solution is to use the NAS and run iSCSI over 1Gb
Ethernet. Slightly off-topic for pgsql-general, but can anyone offer any
performance comparisons between our existing 1Gb SAN and a 1Gb NAS solution?
My feeling is that the SAN will be faster but I have no real way of testing.

Finally, if it helps, the database server is a dual Opteron with 12Gb RAM
running FC4.


Thanks in advance,

Mark.

------------------------
WebBased Ltd
17 Research Way
Plymouth
PL6 8BT

T: +44 (0)1752 797131
F: +44 (0)1752 791023

http://www.webbased.co.uk
http://www.infomapper.com
http://www.swtc.co.uk

This email and any attachments are confidential to the intended recipient
and may also be privileged. If you are not the intended recipient please
delete it from your system and notify the sender. You should not copy it or
use it for any purpose nor disclose or distribute its contents to any other
person.




---------------------------(end of broadcast)---------------------------
TIP 6: explain analyze is your friend