scl@sasha.acc.virginia.edu (Stephen C. Losen) writes:
Looks like by default you get 1 inode for every filesystem data block (4K block size).
That was the old scheme, where the default was 1 inode / 4KB and the minimum allowed 1 inode / 32KB (roughly). These days the default (and minimum) for a flexible volume is the old minimum. That's probably why people run out of inodes more often than they used to.
Adam.Fox@netapp.com (Adam Fox) writes:
The only caveat with adding inodes is to add them as you need them. Don't massively over-add inodes as you'll increase some structures in the filesystem that could slow down your performance unecessarily.
I think the word that should be emphasized there is "massively". It's no more sensible to have your inode metafile always nearly full than to have your aggregates/traditional-volumes in that state. There are overheads that increase if you do.
There is a hidden 5% reserve in the inode metafile (i.e. it is really 20/19 times the maxfiles value, as you can see by looking at the inode numbers actually used) which is meant to stop inode allocation going exponential on you (like the 10% space reserve in an aggregate). That doesn't mean that operating at the extreme limit allowed is ideal.
There was a major change to the inode allocation algorithm (sometime early in ONTAP 6.x, I think) which substantially improved the performance with the inode metafile nearly full. (It had some deleterious effects in other contexts, though, as I might get around to posting about one of these years.) But there's no point in stressing it unnecessarily.