I've been using RA4x000 as a cheap disk source for applications that do not
require very high disk performance. I had assumed the RA4x000 RAID
systems would bottleneck on the 1 Gbit fibre channel interface, which is
far
more throughput than I could get out even six drives in a RAID 0 array.
Well, I was wrong. I measured performance today on a Proliant 6400R
with
4 GB of memory, copying from a RAID 5 array of five 15K rpm SCSI drives to
a
RAID 5 array with six 15K rpm SCSI drives. Each array is located on a
separate RA4x00 locally attached by a separate Compaq FC 64-bit PCI card.
I am getting an absolutely miserable 2.5 MB per second average write
performance at the destination.
How is the above result possible? Each drive should pull data at minimum
3
MB per second, and five 15K drives in a RAID 5 should give me at minimum
10
MB/second read and write performance. I don't have bottlenecks in system
memory, on the PCI bus, on the fibre channel bus. I just don't see where
the 2.5MB/sec could be coming from unless it's hard coded into the array
itself. I was measuring performance on the "physicaldrive" in Windows
performance monitor, read and write, on each drive defined by the separate
RA4x000 arrays.
What current generation product is going to give me at least 20 MB/second
read and write performance with a RAID 5 array of at least six drives?
Heck, with my commodity home-user SATA arrays I am getting 30 MB/second
read
performance, over gigabit ethernet at that. Does Compaq make anything
on
the low end that can compete with consistent 20 MB/second or faster
average
read and write speeds?
--
Will
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