So Jonathan, you have a concern about the on-disk space
efficiency for small file (more or less subsector). It is a
problem that we can throw rust at. I am not sure if this is
the basis of Claude's concern though.
Creating small files, last week I did a small test. With ZFS
I can create 4600 files _and_ sync up the pool to disk and
saw no more than 500 I/Os. I'm no FS expert but this looks
absolutely amazing to me (ok, I'm rather enthousiastic in
general). Logging UFS needs 1 I/O per file (so ~10X more for
my test). I don't know where other filesystems are on that
metric.
I also pointed out that ZFS is not too CPU efficient at tiny
write(2) syscalls. But this inefficiency rescinds around 8K writes.
This here is a CPU benchmark (I/O is non-factor) :
CHUNK ZFS vz UFS
1B 4X slower
1K 2X slower
8K 25% slower
32K equal
64K 30% faster
Waiting for a more specific problem statement, I can only
stick to what I said, I know of no small file problems with
ZFS; If there is one, I'd just like to see the data.
-r
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