I just completed my server and I am generally happy with it. I am running
openindiana on a dell r510 with 64gb of memory and 12 2tb 7200rpm sas drives. I
have 2 256g Samsung 830s as l2arche. I have noticed a few things. First the
l2arche is basically not being populated at all (only 20g or so). Also when
running a crystaldisk benchmark against the lun on the zfs server, small writes
seem to goto ram. If I perform a test with 100m I get about 800MB/s writes. If
I increase that to 500m I get only about 80MB/s. It seems that the larger
writes go directly to the disk. I have disabled zil with the expectation that
all writes would goto ram but this may not be the case. Below are some numbers
that I pulled. Is there anyway to increase l2arche usage and also ram usage? I
understand that the l2arch may not be populated if most of the activity can fit
in the ram (and it probably can, my total used space is only 300gigs and right
now I am testing this with single user access). But if the reason l2arch isn't
being populated is due to ram availability, then why are some of my writes
skipping ram and going directly to the disk?
ARC syncronous write cache
System Memory:
Physical RAM: 65515 MB
Free Memory : 10187 MB
LotsFree: 1023 MB
ZFS Tunables (/etc/system):
ARC Size:
Current Size: 48921 MB (arcsize)
Target Size (Adaptive): 48921 MB (c)
Min Size (Hard Limit): 8061 MB (zfs_arc_min)
Max Size (Hard Limit): 64491 MB (zfs_arc_max)
ARC Size Breakdown:
Most Recently Used Cache Size: 93% 45557 MB (p)
Most Frequently Used Cache Size: 6% 3364 MB (c-p)
ARC Efficency:
Cache Access Total: 72661651
Cache Hit Ratio: 84% 61140347 [Defined State for buffer]
Cache Miss Ratio: 15% 11521304 [Undefined State for Buffer]
REAL Hit Ratio: 76% 55338630 [MRU/MFU Hits Only]
Data Demand Efficiency: 97%
Data Prefetch Efficiency: 35%
CACHE HITS BY CACHE LIST:
Anon: 8% 5398251 [ New
Customer, First Cache Hit ]
Most Recently Used: 44% 27083442 (mru) [ Return
Customer ]
Most Frequently Used: 46% 28255188 (mfu) [ Frequent
Customer ]
Most Recently Used Ghost: 0% 141042 (mru_ghost) [ Return
Customer Evicted, Now Back ]
Most Frequently Used Ghost: 0% 262424 (mfu_ghost) [ Frequent
Customer Evicted, Now Back ]
CACHE HITS BY DATA TYPE:
Demand Data: 65% 40237050
Prefetch Data: 9% 5777420
Demand Metadata: 24% 15098015
Prefetch Metadata: 0% 27862
CACHE MISSES BY DATA TYPE:
Demand Data: 7% 864227
Prefetch Data: 91% 10540593
Demand Metadata: 0% 112421
Prefetch Metadata: 0% 4063
---------------------------------------------
pool
alloc
free
read
write
read
write
-------------
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PSC.Net
442G
10.4T
0
0
0
0
mirror
73.6G
1.74T
0
0
0
0
c2t0d0
-
-
0
0
0
0
c2t1d0
-
-
0
0
0
0
mirror
73.8G
1.74T
0
0
0
0
c2t2d0
-
-
0
0
0
0
c2t3d0
-
-
0
0
0
0
mirror
73.8G
1.74T
0
0
0
0
c2t4d0
-
-
0
0
0
0
c2t5d0
-
-
0
0
0
0
mirror
73.8G
1.74T
0
0
0
0
c2t6d0
-
-
0
0
0
0
c2t7d0
-
-
0
0
0
0
mirror
73.7G
1.74T
0
0
0
0
c2t8d0
-
-
0
0
0
0
c2t9d0
-
-
0
0
0
0
mirror
73.8G
1.74T
0
0
0
0
c2t10d0
-
-
0
0
0
0
c2t11d0
-
-
0
0
0
0
cache
-
-
-
-
-
-
c2t12d0p2
24.8G
194G
0
0
0
0
c2t13d0p2
24.4G
194G
0
0
0
0
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