On Feb 6, 2007, at 11:46, Robert Milkowski wrote:
Does anybody know how to tell se3510 not to honor write cache
flush
commands?
JE> I don't think you can .. DKIOCFLUSHWRITECACHE *should* tell the
array
JE> to flush the cache. Gauging from the amount of calls that zfs
makes to
JE> this vs ufs (fsck, lockfs, mount?)
correction .. UFS uses _FIOFFS which is a file ioctl not a device
ioctl which makes
sense given the difference in models .. hence UFS doesn't care if the
device write
cache is turned on or off as it only makes dkio calls for geometry,
info and such.
you can poke through the code to see what other dkio ioctls are being
made by z ..
i believe it's due to the design of a closer tie between the
underlying devices and
the file system that there's a big difference. The DKIOCFLUSH PSARC
is here:
http://www.opensolaris.org/os/community/arc/caselog/2004/652/spec/
however I'm not sure if the 3510 maintains a difference between the
entire array cache
and the cache for a single LUN/device .. we'd have to dig up one of
the firmware
engineers for a more definitive answer. Point well taken on shared
storage if we're
flushing an array cache here :)
---
.je
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