Geoff;

You've done some good research: I'm seeing similar numbers you're finding on 36 and 72GB disks. However, notice that the space efficiency is going to vary dramatically with the size of the RAID group. That should not be surprising: a two-spindle volume's real availability drops to 33%. (48GB / 144GB ... everyone sees that with vol0...)

I believe it's possible, if you make the raid group very large and use RAID-DP, you could increase space efficiency and performance too.

I don't have 144GB numbers for you, but the "250GB" drives in an R200 work out to less than 200GB usable. I'll try to post some numbers to the list later this week...

JKB

-----Original Message----- From: owner-toasters@mathworks.com [mailto:owner-toasters@mathworks.com] On Behalf Of Geoff Hardin Sent: Wednesday, August 18, 2004 8:20 PM To: toasters Subject: usable size of a 146-GB drive

I was just wondering if anyone had any info on the usable size of the 146-GB drives from NetApp. I am trying to figure out how many drives I'll need, but I can't really tell without knowing what my usable space will be.

If it helps, here's some data I have collected from other drives.

18 GB disk - becomes 17.0 GB because of disk overhead (right size) - becomes 14.923389 because of OS overhead - becomes 13.431053 with a 10% snap reserve - becomes 11.938713 with a 20% snap reserve

36 GB disk - becomes 33.917 GB because of disk overhead - becomes 31.776308 because of OS overhead - becomes 27.273826 with a 10% snap reserve - becomes 25.421048 with a 20% snap reserve

72 GB disk - becomes 67.906 GB because of disk overhead - becomes 59.747608 because of OS overhead - becomes 53.772850 with a 10% snap reserve - becomes 47.798088 with a 20% snap reserve

Thanks,

Geoff Hardin UNIX System Administrator Dallas Semiconductor / Maxim Integrated Products geoff.hardin@dalsemi.com It's illegal to walk your elephant without a leash in Wisconsin.