zfs discuss - Nov 2007 - Unreasonably high sys utilization during file create operations.

While doing some testing of ZFS on systems which house the storage backend for a
custom imap data store I have witnessed 90-100% sys utilization during
moderately high file creation periods. I''m not sure if this is
something inherent in the design of ZFS or if this can be tuned out. But the sys
usage goes so high as nto cause blocking on tcp operations for observable
periods as long as 20-40 seconds. This effectively makes the system unusable for
it''s designed goal as the tcp delay is longer than could reasonably be
expected as a timeout value for the network services/clients which run/utilize
the server.

Any insight would be greatly appreciated. 
This behavior is observed on freshly installed sol10u4 (patched to latest
10_recommended) on coolthreads t1000 servers using dual 10k rpm drives.

Thanks in Advance.

Here''s a an excerpt from vmstat showing 100% sys utilization:

 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr s0 s2 -- --   in   sy   cs us sy id
 19 0 0 19502744 3999456 366 9912 2194 0 0 0 0 0 0 0 0 24868 112987 58937 49 49
2
 5 0 0 19499696 4001416 345 3951 3501 0 0 0 0 0 0 0  0 36075 168337 96305 57 40
3
 1 0 0 19492128 3993160 450 4542 2275 0 0 0 0 0 0 0  0 38505 128766 82580 25 46
29
 14 0 0 19488608 3989880 30 207 0 0 0 0  0  0  0  0  0 3042 3932 3106  1 75 24
 214 0 0 19488800 3990048 0 2 5 0  0  0  0  5  5  0  0 2647 1717 1767  0 97  3
[b]242 0 0 19489568 3990776 0 1 0 0  0  0  0  0  0  0  0 2548 1057  387  0 100
0[/b]
[b]298 0 0 19489568 3990776 0 0 0 0  0  0  0  1  0  0  0 2523 1086  587  0 100
0[/b]
 43 0 0 19481184 3980456 1289 31472 2499 0 0 0 0 144 145 0 0 32371 179144 97796
44 54 2
 2 0 0 19481872 3974600 2125 9766 5922 0 0 0 0 96 96 0 0 40929 170587 112274 37
55 7
 0 0 0 19486568 3974504 551 1110 2632 0 0 0 0 107 107 0 0 35579 95488 77269 17
31 52
 0 0 0 19485136 3969520 354 1310 2183 0 0 0 0 125 125 0 0 24527 56481 46909 11
17 72
 
 
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Was that with compression enabled ?

Got "zpool status" output ?

-r

No compression enabled. Zpool status and more info on the the config is listed
in this other thread:

http://www.opensolaris.org/jive/thread.jspa?threadID=44033&tstart=0

Wasn''t getting a response here, so I looped in the code forum.
 
 
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