We've had a requirement for a NAS fairly recently so I assembled some parts and came up with a NAS running Openfiler 2.3 (Redhat based)
The object of this unit is to run NFS share for a couple of vmware servers and a backup solution for our other servers.
So the Problem: Raid 5 write speed!!
The Servers Hardware consists of
INTEL: E8400 - INTEL CORE 2 DUO 3.00GHZ
S3210SHLX - SERVER MB
8GB of Ram
TST ESR-208 SAS/SATA 2U Case, 8x Hot swap HDD, 600W Power Supply,
8 x Seagate SATAII NCQ 1.5TB 7200RPM 32mb Cache 10TB (Raid5)
1 x 320Gb SATA 2.5" HDD (os drive)
exFujitsu LSI Logic / Symbios Logic MegaRAID SAS 1078 (rev 03)
Simple DD test I'm only getting around
sync ; date ; time dd if=/dev/zero of=bigfile bs=1M count=10000 ; date ; time sync ; date
Wed Apr 21 19:53:26 EST 2010
10000+0 records in
10000+0 records out
Wed Apr 21 19:56:52 EST 2010
Wed Apr 21 19:57:11 EST 2010
So around 48mb/s, Write.
So the issue I'm having is i'm only able to obtain 30-50mb/s Write speed
in the array however easily obtaining over 500+Megabytes/s read.
I understand raid 5 takes a pretty big performance hit however i would have expected over 100mb/s.
I Currently have write-back caching enabled on the raid volume.