Question regarding mmap on ZFS, or possibly Dovecot
Svein Skogen
svein-listmail at d80.iso100.no
Sat May 10 07:03:26 UTC 2008
I still get massive file corruption when allowing Dovecot to run win
mmap enabled on ZFS/FreeBSD RELENG_7 (as of one week ago), and I have
seen symptoms of corruption with Samba and mmap on ZFS (although I
cannot say with certainty that those samba files were corrupted in the
FreeBSD end, they may have been mangled by my less-than-trustworthy
windows).
For dovecot+mmap+zfs I get a googlefull of results, same with
samba+mmap+zfs.
The question remains the same, however. Is this a problem with
samba/dovecot using mmap incorrectly, a problem with ZFS as such, or a
problem with the FreeBSD implementation of ZFS? I'm not asking this to
have someone to point fingers at, but because I want to do some
risk-reducing activities. If the problem is in the applications,
disabling mmap in those applications will be a workaround. If the
problem is with ZFS itself, or with FreeBSD, things start to get
interesting (it would need some global switch to turn mmap off, and I'm
not sure such a thing is practical/possible).
The system running my ZFS is an Athlon64 running amd64 kernel, 4gb ram,
and a raidZ of 3 500gb samsung disks (on an nForce430 chipset)
//Svein
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