----- Original Message -----
From: "Karl Denninger" <k...@denninger.net>
Stick this in /boot/loader.conf and see if your lockups goes away:
vfs.zfs.write_limit_override=1024000000
...
If it turns out that the write_limit_override tunable is the one
responsible for stopping the hangs I can drop the ARC limit tunable
although I'm not sure I want to; I don't see much if any performance
penalty from leaving it where it is and if the larger cache isn't
helping anything then why use it? I'm inclined to stick an SSD in the
cabinet as a cache drive instead of dedicating RAM to this -- even
though it's not AS fast as RAM it's still MASSIVELY quicker than getting
data off a rotating plate of rust.
Now interesting you should say that I've seen a stall recently on ZFS
only box running on 6 x SSD RAIDZ2.
The stall was caused by fairly large mysql import, with nothing else
running.
Then it happened I thought the machine had wedged, but minutes (not
seconds) later, everything sprung into action again.
Am I correct that a ZFS filesystem does NOT use the VM buffer cache
at all?
Correct
Regards
Steve
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