Patrick Lauer wrote:
On Wed, 2006-02-01 at 07:54 -0500, Sean Cook wrote:
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
They are all different questions:
* Hardware RAID vs Software RAID
Hardware RAID offers more performance and often more sophisticated RAID
features.
That is debatable :-)
For really high-end systems hardware raid (3ware, SAN box, ...) is more
performant, but even on a modestly loaded Athlon64 you'll (usually) be
I/O limited before CPU limits become visible
It is, nearly everything surrounding performance on RAID is debatable.
Depends on your usage and controller and disk-types etc.
Dependant on what you do you might hit an I/O limit faster than an
CPU-limit.
Agreed.
Another advantage is that Hardware RAID controllers often offer you the
opportunity to extend your RAID array beyond the usual 4 SATA
interfaces. Depends on the card though.
I'm running a software raid spanned over 3 controllers ... I'm not aware
of a hardware-based solution that even comes close to that flexibility.
How many disks can you put in ?
AFAIK most motherboard interfaces support 4 SATA disks
Back in the day... we were running the LSI MegaRAID controllers with
RAID 1 on 9gig SCSI disks, we were choking our application
(mysql/mod_perl) we took the MegaRAID controller out and performance
increased by about 25%. (note: this is a real world situation)
Even if this is anecdotal - my experience is very similar.
Software raid5 on an Athlon-1000 (basically a box of leftovers) takes
~7% CPU to saturate a 100Mbit line. An older 3ware controller maxed out
at similar speeds, slightly lower CPU load - but adding more RAM and a
slightly faster CPU is in this case much cheaper and faster than buying
a new controller. Also changing controllers might not be possible
without wiping and rebuilding the array.
But if you need a disk array with maximum performance I'd still suggest
a hardware-based solution.
Me too :-)
But considering your comments, why ?
Grtz Ramon
--
To be stupid and selfish and to have good health are the three requirements for
happiness, though if stupidity is lacking, the others are useless.
Gustave Flaubert
--
[email protected] mailing list
