[OpenAFS] OpenAFS with RAID

Andrew Bacchi bacchi@rpi.edu
Wed, 28 Dec 2005 09:05:13 -0500

Paul Robins wrote:

> I would expect a disk to be the thing to go to be honest but 
> regardless, i want some system where there is parity data stored on 
> other nodes in this group of machines. Basically RAID5 but networked 
> would be perfect, as that would give me ~ 400 gig of space whilst 
> being able to handle a machine vanishing from the network (the whole 
> machine dies when the disk does, cheap whiteboxes don't you know)

I think you have to abandon the "network RAID" idea.  You may be 
referring to SAN storage, in which case RAID is unnecessary.  You could 
use RAID 1 for mirroring your data disk, or RAID 5 to combine multiple 
disks into one file space, with a hot spare - very reliable and 
redundant..  But that is on a machine basis, not a group of machines.

> I understand the way AFS works with regards to clients seeing /afs, 
> and i did see read only replication, and then running a command to 
> change a read only node(?) into a read write node (i'm sorry if i'm 
> talking crap, i'd read the wiki if i could). This is why i figured 
> perhaps it could be implimented with some sort of networked RAID5, 
> giving me a lot more storage than just RO mirroring one server to the 
> other 3, but whilst still being redundant. 

If you were to use RO volumes for EVERY volume on your system, you would 
have a administator nightmare.  It is recommended that only infrequently 
changed volumes be replicated.  Each time you change the volume data, 
you would need to 'vos release' that change to the RO volume(s).

veritatis simplex oratio est
		- Seneca

Andrew Bacchi
Staff Systems Programmer
Rensselaer Polytechnic Institute
phone: 518 276-6415  fax: 518 276-2809