Milosz,
Please consider switching to the iSCSI Target that is part of COMSTAR:
http://docs.sun.com/app/docs/doc/819-2240/itadm-1m
http://docs.sun.com/app/docs/doc/819-2240/sbdadm-1m
http://docs.sun.com/app/docs/doc/819-2240/stmfadm-1m
- Jim
hi all,
i've posted about this before, but i've done some work since then
and i'd like to run it by people again.
i'm having what seem to be two (maybe related, maybe not) issues
with windows -> snv_111 network/iscsi performance.
hardware: snv_111 on homebrew box intended for san/nas use, intel
server gigabit nics, windows server 2003 on dell pe 1950, broadcom
nics.
(1) saturation on iscsi writes (from ms iscsi initiator -> snv_111)
is useless: getting around 12% of gigabit.
(2a) iscsi write also suffers from periodic dips. as in, i'll get
15% saturation for a couple of seconds, then 0% for a second, repeat.
(2b) i am able to get to around 50% utilization with: iscsi read,
cifs read, cifs write. the cifs writes suffer from periodic dips as
well, but they are not as dramatic as the iscsi write dips (50% ->
~25%).
here is what i have done to optimize:
(1) set default mtu on e1000g interfaces to 9000 in e1000g.conf
(2) turned on jumbo frames on the switch and broadcom nics on
windows box.
(3) turned off nagle's algorithm in windows.
(4) turned off nagle's on solaris (ndd -set /dev/tcp tcp_naglim_def 1)
(5) windows: set sackopts=1, tcp1323opts=3 (window scaling),
tcpreceivewindow=400k
(6) solaris: set tcp_recv_hiwat to 400k
(7) solaris: iscsitadm modify target -m 400000
(8) turned off lso_enable and tx_hcksum_enable in e1000g.conf (this
is precautionary, since there have been issues in the past)
(9) turned off lso and tco on broadcom nics (again, precautionary).
iperf results:
solaris -> windows: steady 99% network utilization, perfect.
windows -> solaris: around .1% utilization (yep, less than 2
megabits max) unless i specify 400k as the default window size for
the client-side iperf; in that case i get 98% with periodic dips to
40-80%
notes:
--netstat -f inet shows proper send & receive window sizes (400k).
--not seeing anything unusual; snoop/tcpdump captures look fine; not
seeing any errors on nics or switchports.
--results identical with lso & tco enabled/disabled on both sides
--windows -> windows cifs reads & writes are steady at 58%
so: any ideas? based on the iperf evidence i think windows tcp
window scaling might not be working correctly (even though it seems
to be working more or less fine for cifs), which would maybe explain
issue (1). issue (2), the periodic dips in transfer, i don't really
know how to explain, but it is specific to windows -> solaris
operations.
anyone else doing windows -> solaris iscsi?
thanks,
milosz
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