ZFS tuning [was: hardware for home use large storage]

[Bartosz Stec]

On 2010-02-17 08:58, jhell wrote:
>
> To all those involved in this.
>
> More up-to-date: arc_summary.pl r182
>
>
> Best regards.
>
> And watching for replies,
>
So here's my reply (last line seems most interesting ;) :

# ./arc_summary.pl
---------------------------------------------------------------------
System Summary śro 17 lut 2010 08:16:37 UTC

FreeBSD 9.0-CURRENT #20: Fri Feb 12 19:21:34 CET 2010 ncpnc

Kernel Version: 900009 (osreldate)

Hardware Platform: i386
Processor Architecture: i386

Storage pool Version: 14
Filesystem Version: 3

Physical RAM: 1523.41 MiB


Kernel Memory Usage
TEXT: 9782828, 9.33 MiB
DATA: 216801280, 206.76 MiB
TOTAL: 226584108, 216.09 MiB

9:16 up 4 days, 6:54, 1 user, load averages: 0,47 0,92 0,59
---------------------------------------------------------------------

ARC Summary

Meta Limit: 120.00 MiB
Meta Used: 135.00% 162.00 MiB

Throttle Count: 0

ARC Size:
Current Size: 190.03 MiB (arcsize)
Target Size (Adaptive): 209.12 MiB (c)
Min Size (Hard Limit): 60.00 MiB (arc_min)
Max Size (Hard Limit): 480.00 MiB (arc_max)

ARC Size Breakdown:
Recently Used Cache Size: 16.00% 33.46 MiB (p)
Frequently Used Cache Size: 84.00% 175.66 MiB (c-p)

ARC Efficiency:
Cache Access Total: 28459411
Cache Hit Ratio: 94.57% 26913166
Cache Miss Ratio: 5.43% 1546245
Actual Hit Ratio: 81.81% 23282481

Data Demand Efficiency: 99.48%
Data Prefetch Efficiency: 54.15%

CACHE HITS BY CACHE LIST:
Anonymous: 11.07% 2978474
Most Recently Used: 16.42% 4419712 (mru)
Most Frequently Used: 70.09% 18862769 (mfu)
Most Recently Used Ghost: 0.98% 264205 (mru_ghost)
Most Frequently Used Ghost: 1.44% 388006 (mfu_ghost)

CACHE HITS BY DATA TYPE:
Demand Data: 53.58% 14419664
Prefetch Data: 0.07% 20017
Demand Metadata: 32.68% 8794182
Prefetch Metadata: 13.67% 3679303

CACHE MISSES BY DATA TYPE:
Demand Data: 4.88% 75410
Prefetch Data: 1.10% 16946
Demand Metadata: 59.18% 915133
Prefetch Metadata: 34.84% 538756


L2 ARC Summary

Low Memory Aborts: 0
Bad Checksums: 0
IO Errors: 0

L2 ARC Size:
Current Size: 0.00 MiB
Header Size: 0.00 MiB

L2 ARC Breakdown:
L2 Access Total: 0
Illegal division by zero at ./arc_summary.pl line 242.

-- 
  Bartosz Stec