[Asterisk-Users] RAID affecting X100P performance...

[Walt Reed]

On Wed, Jul 21, 2004 at 06:15:23PM -0400, Andrew Kohlsmith said:
> On Wednesday 21 July 2004 16:33, Steven Critchfield wrote:
> > Software raid is bad. IDE hardware raid isn't much better. Software raid
> > is always going to eat your system alive since the CPU has to be busy
> > with 2 or more writes as opposed to it's normal 1.
> 
> I've never had issues with IDE RAID1 -- rebuild can be CPU costly but you can 
> throttle it with the /proc interface.  And issuing two async writes should 
> not be that terrible on a system.

I've never had trouble on my SCSI based software raid either for
asterisk (low load though...) even with multi-hour long conference
calls.  Never a peep, echo, anything. Perfect audio (xp100 with Cisco
ATA 186.) My * server is also my mail server, web server, etc.
(something I normally wouldn't suggest.)
 
> > Raid 5 spreads the load over spindles and should take less CPU total,
> > but don't bet on it if it is IDE.
> 
> RAID5 involves calculating the checksum/parity information (ok it's only an 
> XOR but still) -- I've never used IDE SW RAID5.
> 
> > Go SCSI or don't do RAID.
> 
> SCSI is good, yes, but really, how is a decent IDE (especially SATA) drive 
> much different from SCSI these days in terms of CPU use?

I've had no problems with a Intel ICH5R based SATA software raid setup.
They show up in Linux as SCSI drives (libata path in the 2.4 kernels.)
I've heard very good things about 3ware SATA / IDE cards in regards to
processor load, hardware raid, etc. Some of the IDE chipsets are REALLY
horrible. Unless you know that your's is one of the good ones, it would
be best to avoid it (in regards to RAID anyway.)