Date: Mon, 3 Nov 2014 22:29:48 -0800 From: George Kola <georgekola@gmail.com> To: freebsd-stable@freebsd.org Cc: alc@FreeBSD.org, gibbs@FreeBSD.org, kib@FreeBSD.org Subject: ARC size limit Message-ID: <3B70EA0C-0976-49D6-8418-6B5D22ED7E65@gmail.com>
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Hi All,
This is my first post to freebsd-stable fresh of Meet BSD =
California 2014. We are switching our entire production to FreeBSD. Our =
storage servers have 256 GB of RAM , 4 TB of SSD and 40 TB of spinning =
disks. We are running ZFS root and the SSD is configured as L2ARC. We =
are running FreeBSD 10.1 RC3
I am finding that on all our machines, ARC is somehow limited to =
< 64 GB of memory and we have a huge inactive memory (180 G). The =
surprising thing is that ARC seems to have almost the same limit (< 64 =
GB) on all of our storage boxes and ARC is not growing even though L2ARC =
hit shows that there is advantage in growing ARC.
Any help/pointers is appreciated.
What I am trying to do is to tune ZFS for our workload. We are =
hoping that we get a high hit rate.=20
Thanks to Justin Gibbs and Allan Jude for initial pointers and =
help. They suggested posting to the mailing list to get further help.
I have pasted top output and zfs-stats output below and yes UMA =
is enabled.
Thanks,
George
=20
top
last pid: 27458; load averages: 3.30, 5.42, 5.34 =
=
up 6+09:59:30 05:38:49
71 processes: 1 running, 70 sleeping
CPU: 4.2% user, 0.0% nice, 4.6% system, 0.2% interrupt, 90.9% idle
Mem: 11G Active, 181G Inact, 52G Wired, 1368M Cache, 4266M Free
ARC: 47G Total, 1555M MFU, 41G MRU, 35M Anon, 3984M Header, 709M Other
Swap: 64G Total, 2874M Used, 61G Free, 4% Inuse
sysctl vfs.zfs.zio.use_uma
vfs.zfs.zio.use_uma: 1
zfs-mon -a output
ZFS real-time cache activity monitor
Seconds elapsed: 62
Cache hits and misses:
1s 10s 60s tot
ARC hits: 124 126 103 101
ARC misses: 35 46 29 28
ARC demand data hits: 55 90 61 61
ARC demand data misses: 20 32 18 17
ARC demand metadata hits: 69 36 42 40
ARC demand metadata misses: 9 13 10 9
ARC prefetch data hits: 0 0 0 0
ARC prefetch data misses: 6 1 1 1
ARC prefetch metadata hits: 0 0 0 0
ARC prefetch metadata misses: 0 0 0 0
L2ARC hits: 16 28 14 14
L2ARC misses: 19 18 15 14
ZFETCH hits: 592 2842 2098 2047
ZFETCH misses: 308 1326 507 494
Cache efficiency percentage:
10s 60s tot
ARC: 73.26 78.03 78.29
ARC demand data: 73.77 77.22 78.21
ARC demand metadata: 73.47 80.77 81.63
ARC prefetch data: 0.00 0.00 0.00
ARC prefetch metadata: 0.00 0.00 0.00
L2ARC: 60.87 48.28 50.00
ZFETCH: 68.19 80.54 80.56
zfs-stats -a output
ZFS real-time cache activity monitor
Seconds elapsed: 62
Cache hits and misses:
1s 10s 60s tot
ARC hits: 124 126 103 101
ARC misses: 35 46 29 28
ARC demand data hits: 55 90 61 61
ARC demand data misses: 20 32 18 17
ARC demand metadata hits: 69 36 42 40
ARC demand metadata misses: 9 13 10 9
ARC prefetch data hits: 0 0 0 0
ARC prefetch data misses: 6 1 1 1
ARC prefetch metadata hits: 0 0 0 0
ARC prefetch metadata misses: 0 0 0 0
L2ARC hits: 16 28 14 14
L2ARC misses: 19 18 15 14
ZFETCH hits: 592 2842 2098 2047
ZFETCH misses: 308 1326 507 494
Cache efficiency percentage:
10s 60s tot
ARC: 73.26 78.03 78.29
ARC demand data: 73.77 77.22 78.21
ARC demand metadata: 73.47 80.77 81.63
ARC prefetch data: 0.00 0.00 0.00
ARC prefetch metadata: 0.00 0.00 0.00
L2ARC: 60.87 48.28 50.00
ZFETCH: 68.19 80.54 80.56
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