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sh-3.2$ sudo zdb -tune list
VARIABLE VALUE SOURCE
vdevmaxpending 10 default
vdevminpending 4 default
dmuprefetch 1 default
scrubprefetch 1 default
– with the understanding (from Ten's Complement beta testing) that they're for performance analysis only.
My current overrides (first experiment):
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gpes3e-gjp4:~ gjp22$ sudo zdb -tune list
VARIABLE VALUE SOURCE
vdevmaxpending 1 override
vdevminpending 1 override
dmuprefetch 0 override
scrubprefetch 0 override
Within the limitations of my MacBookPro5,2 (8 GB memory, single sshd used for both HFS Plus boot and ~500 GB ZFS home directory): early results are pleasing. There's the usual creep up to around thirty-three percent equity (reported by zstat), but the Mac feels much more responsive following login to that home, and during the period of creep. I'll probably not attempt to benchmark but so far, it certainly feels better.
Has anyone else experimented with the four tunables?
I'll be particularly interested to hear from people whose Macs are similarly constrained. Thanks.
Notes
Without overrides, zstat output 2013-05-12 03:46:49
With overrides, zstat output 2013-11-13 17:27:38
In the latter: no DMU zfetch measurement, and I guess that the misses for ARC prefetch data and ARC prefetch meta are negligible …
… I have a launch daemon that sets the tunables before I unlock the Core Storage logical volume for my ZFS home.
Related
ZEVO support topics include:
- Overall performance of the OS, filing systems and apps (2012-09-26)
- Performance issues (2012-12-06)
- ZEVO performance success stories? (2012-12-07)
- Performance: changes of priority for scrub (verification) (2013-04-07)
Elsewhere: