[sclug] RAID 5

[Keith Edmunds]

Peter Brewer wrote:
> We're currently setting up a fileserver using RAID 5.  It consists of 8x 
> 250Gb HD's each partioned something like this:
> 
> 512Mb
> 5Gb
> 40Gb
> 185Gb
> 
> Which gives us final reported partitions:
> 
> 4Gb = Swap
> 33Gb = /
> 280Gb = /home
> 1.3Tb = /data

Hi Peter

The first observation would be that it looks as if you are not swapping 
to RAID partition, but to all eight drives in parallel. Nothing wrong 
with that, but be aware that if any one drive fails then there is a very 
good chance that the system will die also.

> We are running Debian and when we set up the RAID we set all 8 disks to 
> active and none to inactive (not entirely sure whether we needed an 
> inactive disk or not).  All seems to be working fine except when we 
> simulated a disk failure by booting up with just 7 disks.  Debian 
> detects the missing disk and continues to boot happily.  After I log in, 
> both root and /home seem to be intact however /data is empty.  Why would 
> it successfully recover just 2 of the 3 RAID partitions when they've all 
> been set up in the same way?

"Recover" is a bit of a misnomer here - it hasn't recovered the 
partition, merely reconstructed the data from what is left. But maybe 
I'm being picky, sorry! Anyway, my first thought would be "is the /data 
partition mounted"? It seems unlikely that all the data would just 
disappear.

Keith

-- 
Keith Edmunds

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