On 15-03-12 07:37 AM, Sebastian Gabler wrote:
Hi,
I have 12 GB RAM, 20 GB total pool size machine. L2ARC for one pool is
107G SSD. I am wondering a bit about:
- why not more of the RAM is used by ARC (I have run the ARC
optimisation script from the evil tuning guide, there machine is file
server exclusively, so no other apps steal RAM)
- why the hit rate on the l2ARC is rather small (is it because the hit
rate on ARC is rather ok, which is what I think?)
- would it help the quality of the service I am providing trying to
increase the prefetch hit rate, and how could I achieve that if.
Sample from arcstat:
time hit% dh% ph% mh% l2hit% arcsz
14:20:52 92 99 27 99 1 4.5G 4.5G
14:21:52 92 99 28 99 1 4.5G 4.5G
14:22:52 92 99 31 99 1 4.7G 4.7G
14:23:52 93 99 30 99 1 4.5G 4.5G
14:24:52 92 99 27 99 1 4.5G 4.5G
14:25:52 92 99 30 99 1 4.5G 4.5G
14:26:53 92 99 27 97 1 4.5G 4.5G
14:27:53 93 99 30 99 1 4.5G 4.5G
14:28:53 92 99 28 99 1 4.5G 4.5G
14:29:53 93 99 29 99 1 4.5G 4.5G
14:30:53 92 99 28 99 1 4.5G 4.5G
14:31:53 92 99 30 99 1 4.5G 4.5G
14:32:53 93 98 30 99 2 4.5G 4.5G
14:33:53 92 99 28 99 1 4.5G 4.5G
14:34:53 92 99 27 99 1 4.5G 4.5G
14:35:53 92 99 32 99 1 4.6G 4.6G
14:36:53 89 98 32 99 0 4.5G 4.5G
14:37:53 92 99 30 99 1 4.5G 4.5G
14:38:53 92 99 28 99 1 4.5G 4.5G
14:39:53 93 99 28 98 2 4.5G 4.5G
14:40:53 93 99 29 99 1 4.5G 4.5G
Hi Sebastian.
Is it possible the working set of data is ~ 4.5GB in size?
Also, you may want to use arc_summary as a tool to get a better
understanding of your ARC usage
http://www.cuddletech.com/arc_summary.pl
Geoff
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