David Cooley wrote:
> If you'll have lots of small files, try a chunk size of 4K... should keep
> waste to a minimum. On the other for the mirror FTP, 16 is probably a good
> compromise.
AFAIK, chuck size affects only performance, not waste of disk. I seem
to recall that it controls how many 1k disk blocks is accessed on one
disk before switching to the next. Am I right?
On the other hand, choosing a suitable block size when creating a
filesystem is quite important and tightly connected to the predicted
average file size. If you make a bad choice here, waste (or inode
starvation) is then a real issue. But that problem exist whether or
not you're using a RAID system.
I have seen recommendations of using chunk sizes as high as 256 on
large RAID-5 (>50GB). I have seen no proof whether this is a good
choice or not. For example, I have for a ~100GB RAID-5 md device
choosen a chuck size of 256, a block size of 4k, and a stride of 64
(as parameter to mkfs). The performance seem okey so far.
<tomas/>
