On Mon, 30 Aug 1999, Lawrence Dickson wrote:
> I guess this has been asked before, but - when will the RAID code get
> past the 12 disk limit? We'd even be willing to use a variant - our
> customer wants 18 disk RAID-5 real bad.
yes, this has been requested before. I'm now mainly working on the 2.3/2.4
merge, it's working but it has unearthed main kernel bugs. I have patches
for up to ~250 disks per array, but these patches are not proven and it's
a major change in the superblock layout.
until these 'big RAID' patches are merged, as a workaround i suggest you
to combine two (or more) RAID5 arrays with RAID0 or LINEAR to form a
bigger array. Data safety is not compromized with this, system
administration is a bit more complex. (also you cannot get a better than
1:12 parity/data ratio) On the bright side, this setup provides you more
protection than pure 1:18 RAID5. (eg. if you do it 2x 1:9, then the two
RAID5 arrays can fail at once, there is a 50% chance that simultaneous
2-disk failures will be covered by this.)
-- mingo
