Re: Raid0 needs more memory.
Vadim E. Kogan (vadim@vadim.biz-net.net)
Tue, 01 Jul 1997 00:48:11 -0700
Tall cool one wrote:
>
>
> Recently I tried to make a 12GB raid0 array of 3 4GB drives and watched the
> system die horribly when the raid0 personalty failed to get the 240K or so it
> asked for and proceeded to try to work without it anyway. The MD developers
> should make the raid0 personality fail nicely if it can't get the memory it
> allocated (two if statements as I recall), but in order to actually work,
> kmalloc() needs to support larger bucket sizes (256K at least). Even two 4GB
> drives for an 8GB array would fail when it needed 143K, although it would
> sometimes succeed? (may have been playing with the chunk size at the time,
> the hash seems to grow with larger chunks).
>
The problem is probably because your partitions are *ALMOST* the same -
this gives *small* strip size, that gives *BIG* nr_zones. I got
situation when it I had smallest->size=128 ;-) and nr_zones=98273. (on
4Gb drives). So it asked for 786184.
Probably your patch will fix that, but IMHO that's not a correct way.
Correct way is to find such problems and just "forget" about this 128.
This will REALLY reduce memory requirenments, coz it will make *less*
strips.
Vadim