I'm working on this scenario in which file system activity appears to
cause the arc cache to evict meta data. I would like to have a
preference to keep the metadata in cache over ZFS File Data
What I've notice on import of a zpool the arc_meta_used goes up
significantly. ZFS meta data operations usually run pretty good.
However over time with IO Operations the cache get's evicted and
arc_no_grow get set.
-bash-3.00# echo ::arc | mdb -k| grep arc
arc_no_grow = 1
arc_tempreserve = 0 MB
arc_meta_used = 277 MB
arc_meta_limit = 3789 MB
arc_meta_max = 1951 MB
-bash-3.00# echo ::arc | mdb -k| grep arc
arc_no_grow = 1
arc_tempreserve = 0 MB
arc_meta_used = 91 MB
arc_meta_limit = 3789 MB
arc_meta_max = 1951 MB
this will have the adverse affect on zfs commands taking longer.
-bash-3.00# echo ::memstat | mdb -k
Page Summary Pages MB %Tot
------------ ---------------- ---------------- ----
Kernel 1185002 4628 29%
ZFS File Data 2186752 8542 53%
Anon 41183 160 1%
Exec and libs 2378 9 0%
Page cache 13202 51 0%
Free (cachelist) 518567 2025 13%
Free (freelist) 195901 765 5%
Total 4142985 16183
Physical 4054870 15839
So, I would like to limit the amount of ZFS File Data that can be used
and keep the arc cache warm with metadata. Any suggestions?
Thanks
Dave
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