[OpenAFS] vice partition sizes, and large disks

chas williams chas@cmf.nrl.navy.mil
Fri, 15 Jun 2001 21:24:22 -0400

>Does it make sense to use the entire array as a single partition(~500GB)
>or should we break it up.

i would say break it up.  depending on your config (raid3/5 in 
particular) a single disk failure can make an entire partition
readonly. of course, mirrors dont have this problem but they
eat more space.  i have no idea if raid3 or raid5 is better for
an afs partition.  when i last checked, i seemed to get the same
general performance.

>thanks for any information you can share on this subject.

i have about 8 16G partitions (raid5) on our 3 fileservers w/o any problems.
there are a few striped partitions at 30G each, but i dont put anything
critical on those partitions since a single disk failure will kill 
those partitions (its a good place for readonly's though since they are
easy enough to regenerate)  the 30G stripes were done with solaris's
disksuite software (its one of the old fibre channel boxes with a bunch
of 9G drives).  disksuite's raid5 performance seems awful (well it is in
software after all, and the e6000 is no speed demon). the 16G partitions
are 'hardware-based' raid5 (ala clariion). 

btw, i really really really wish ufs logging would work with the fileserver.
i corrupted a couple src volumes when i tried this one.  saving the fsck
time on the partitions after a crash would be a big win.

just my thoughts -- i could be completely off my rocker.