View Full Version : Mixed seek times on RAID

06-05-2003, 03:28 PM
I'm currently running an Escalade 7810 RAID with 3 of the 8 channels fitted with Seagate (ST380021A) 80Gb 7200rpm drives. The average seek time on these drives are 9.5ms.

I now want to fill the other 5 channels but the latest Seagate (ST380011A) 80Gb is said to have an 8.5ms average seek time.

For the rest, the drives seem to have identical technical specs.

Will this be a problem mixing these two different drive models in the same RAID 0 configuration?

Jim Capillo
06-05-2003, 03:49 PM
If I remember correctly, you'll see results that will match the lowest capacity/slowest drives.

06-05-2003, 08:44 PM
If I could ask Paul, what kind of results are you getting out of your 3 seagate drives ?
How many uncompressed streams ?

I have an array of 4 of these drives off an Escalade 7800 series IDE controller...

06-06-2003, 01:19 AM
I get about 70Mb/sec from 3 7200rpm IDE Seagates which gives me 2 streams realtime BUT so far I've been running VT[2] on a REALLY inadequate 800MHz single CPU Athlon with 512Mb RAM and the Escalade is sitting in a 32bit PCI slot. The system does run, but only just. Part of my upgrade is to host my VT[2] in a dual 2.4GHz XEON Intel SE7505VB2 box, 1Gb RAM, and all 8 channels RAID running on 64bit PCI.

Paul Lara
06-06-2003, 05:35 AM
Originally posted by Paul_Newman
...and all 8 channels RAID running on 64bit PCI.

Oh, you'll see your bandwidth leap to 150MB+...but even that is going to deliver an additional extra stream (a total of 3).

VT's software-centric operation will make you smile though, since everything you do will take full advantage of the extra horsepower!

...and yes, you can add faster drives to your RAID, but as Jim said, any RAID 0 configuration has to negotiate all drives based on the slowest, and smallest one in the set.