ZFS stalls on Heavy I/O
Levent Serinol
lserinol at gmail.com
Wed Jun 27 09:15:11 UTC 2012
Hi,
Under heavy I/O load we face freeze problems on ZFS volumes on both
Freebsd 9 Release and 10 Current versions. Machines are HP servers (64bit)
with HP Smart array 6400 raid controllers (with battery units). Every da
device is a hardware raid5 where each one includes 9x300GB 10K SCSI hard
drivers. Main of I/O pattern happens on local system except some small NFS
I/O from some other servers (NFS lookup/getattr/ etc.). These servers are
mail servers (qmail) with small I/O patterns (64K Read/Write). Below you
can find procstat output on freeze time. write_limit is set to 200MB
because of the huge amount of txg_wait_opens observed before. Every process
stops on D state I think due to txg queue and other 2 queues are full. Is
there any suggestion to fix the problem ?
btw inject_compress is the main process injecting emails to user inboxes
(databases). Also, those machines were running without problems on
Linux/XFS filesystem. For a while ago, we started migration from Linux to
Freebsd
http://pastebin.com/raw.php?i=ic3YepWQ
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