Re: SATA drives performance

From: gael(at)pilotsystems(dot)net ( Gaël Le Mignot)
To: Ognjen Blagojevic <ognjen(at)etf(dot)bg(dot)ac(dot)yu>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: SATA drives performance
Date: 2009-12-24 15:44:14
Message-ID: plop87637wwf5d.fsf@aoskar.kilobug.org
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Hello,

Instead of using 3 disks in RAID-0 and one without RAID for archive, I
would rather invest into one extra disk and have either a RAID 1+0
setup or use two disks in RAID-1 for the WAL and two disks in RAID-1
for the main database (I'm not sure which perform better between those
two solutions).

RAID-1 will give you about twice as fast reads as no RAID (and RAID
1+0 will give you twice as fast as RAID 0), with no significant
penalty for writing, and it'll save a lot of manpower in case on disk
dies.

If you can afford hot-swappable disks, you can even replace a failed
disk live, in a few minutes, with no failure at software level.

Everything can be remotely setup, including adding/removing a disk
from RAID array, if you use Linux software RAID (mdadm), except of
course the physical swap of the disk, but that can be done by a
non-technician.

This solution costs only one extra disk (which is quite cheap
nowadays) and will deliver enhanced performances and save a lot of
manpower and downtime in case of disk breaking.

Regards,

--
Gaël Le Mignot - gael(at)pilotsystems(dot)net
Pilot Systems - 9, rue Desargues - 75011 Paris
Tel : +33 1 44 53 05 55 - www.pilotsystems.net
Gérez vos contacts et vos newsletters : www.cockpit-mailing.com

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