On Fri, 18 Feb 2011, Wietse Venema wrote: > Please file a ZFS bug reportug. As per POSIX, when the O_CREAT is > specified to open(), > > The third argument does not affect whether the file is open > for reading, writing or for both. > > In other words, read/write access is controlled with the O_RDWR flags, > not the read/write permissions argument. > > When the above error happens, Postfix discards the file. Consequently, > Postfix performance will be reduced, because it creates one extra file > per MAIL transaction, instead of one extra file over the process > lifetime.
That being said, I found ZFS performance abysmal, that is with a single-disk pool (one partition on an enterprise-class 7200/min HDD, amd64, 4 GB DDR3 ECC RAM, Phenom II X4 905e i. e. 4 x 2.5 GHz) on FreeBSD 8.X, and ZFS prefetching enabled in the loader tunable. I'd been running /usr with compression enabled, and stat() effort, writes, and thereabouts were unbearably slow, even with a 85% filled partition (the pool was 100% full one time before). I've switched to UFS2 on a 5400/min eco-consumer-class drive for the nonce and it just flies. I haven't analyzed this, but it seems there still are a few rough edges in ZFS-on-FreeBSD that need to be filed down a bit :) Note that ZFS on FreeBSD also still has a bug that it can't delete files if the partition is full. You need to manually truncate files (to create room for the relevant deletion log entries) before you can remove files. (I've file a problem report for that but don't know the PR # yet.)
