RE: Back to the RAID question

["Joe Pluta" <joepluta@xxxxxxxxxxxxxxxxx>]

<laughing>

Yeah, cache is indeed king.  This RAID question is for an xSeries,
though, so the cost-effectiveness is actually an issue.  RAID-1 costs
quite a bit more than RAID-5.  Also, the ServeRAID cards are
significantly different; the older 6M is rated at 320MB, but the newer
7K is only 256MB.  However, at the same cache (256MB), the 7K is nearly
$1000 cheaper.  You're telling me that the difference between 256MB and
320MB is probably not significant during normal processing, so that
$1000 can go toward RAM or processor speed.

Joe


> From: Jones, John (US)
> 
> Most modern drives can burst-transfer at their spec (320MB/s, for
> instance), but can't sustain anywhere near that.  Sustained transfer
> speeds for a single are still topping out around 80MB/s.
> 
> Anyway, I've run RAID5 on iSeries machines for many, many moons.  It
> works and is decently cost-effective (as far as one can say anything
> disk-related on an iSeries is 'cost effective').  I would, though,
> recommend you use the 2780.  Cache is king. :)