[sclug] RAID 5 - Summary

[Scott Rixon]

Peter Brewer wrote:

> Thank you all for your assistance.  I think all is ok now.   I've 
> reinstalled  Ubuntu from scratch using RAID5 with 7 active disks and 1 
> inactive disk.  The  active/inactive is apparently whether they are 
> actively used in the RAID and nothing to do with boot stuff. So our 
> system now has RAID 5 across 7x 250Gb disks (which gives a total of 
> 1.5Tb as RAID 5 = n-1), with one spare disk waiting in the sidelines 
> to save the day if any of the active RAID disks fail.  This means that 
> a total of 3 disks would have to die in quick succession for us to 
> loose data.
>
<snip>

Just don't forget that with the spare drive the raid must FULLY rebuild 
before it is tollorent again. RAID 5 is all about parity bits and you 
can only ever fail one disk. It's going to take a while to rebuild a 
250gb disk.

I had a customer pull out a drive, watch the hot spare cut in and then 
pull another. One dead RAID!

If we have been over this I am sorry.. Just a subject I know and have 
got involved a little late..

Enjoy your nice new fileserver.

Scott

PS. I would have bought a hardware RAID card with 8 SATA connection. (Oh 
and a hotswap one at that)