How fast should RAID be?

[BR753287]

Hello,

I'm trying to set up a Netserver LH3 with the integrated HP NetRAID Controller. The NOS is Win2k Server. The Server has 6 HP U2W SCSI discs with 9.1GB. 5 of them are configured to a RAID 5 and one is hotspare.
What transfer speed can I expect from the array. I don't want to know any exact values but a raw direction. Because I think my array is much to slow. I got 3-4 MB/s writing and 9 MB/s reading.
I've testet the speed of an old 4GB SCSI-2 Disk and it writes faster and reads as fast as my U2W array!!!

Any ideas?

[CA845876]

These numbers don't sound too out-of-line. I don't know if HP ever released performance numbers for its embedded NetRAID, but it's not all that fast in LH3. For the JBOD SCSI, about 25 MB/s is in the sustainable ballpark, but depends on the kind of drives you have (7200 rpm, 10k, 15k, etc).

I'm assuming that you need the redundancy, and RAID 0 is out of the question. If it isn't (like if you have fixed data that's easily restored), you could get some performance that way.

Another way is to buy a NetRAID 2M or 4M card somewhere, or an equivalent recent card, which will perform much better. Be advised, though, the LH3 does not support 64-bit PCI, and neither does it support 66 MHz PCI.

Turning on the write cache will also boost speed, but with the peril that if the power fails, you'll lose some writes unless you have a battery backup (probably optional) installed. I don't know if the LH3 has a battery backup for write cache or not; the 2M and 4M certainly do.

Another possibility, if your data allows it, is to put all the data that needs to be fast on a RAID 1 (say, take 2 of the drives), with data that's not so time critical on a RAID-5 on the other 4 drives.