Poor iSCSI performance with istgt.

Peter Ankerstål peter at pean.org
Mon Nov 19 13:26:02 UTC 2012


Im using two FreeBSD machines trying to get iSCSI to work and it works 
allright, but extremley slow. It peaks at about 50MB/s if I have 
multiple dd's runningt against the target.

I have two separate networks but I get no difference in speed whichever 
I use. One regular 1G network connected to the same switch with Intel 
cards. I get close to maximum performance with both ftp and iperf.
The other network is a IPoverIB network where I get 560MB/s with iperf 
and 250MB/s with ftp.. (hmm).

Both machines run FreeBSD 9.1-PRE with OFED enabled:
FreeBSD zfs1 9.1-PRERELEASE FreeBSD 9.1-PRERELEASE #0: Tue Oct 16 
16:07:39 CEST 2012     peter at zfs1:/usr/obj/usr/src/sys/OFED  amd64

Im only fiddeling with writes right now and like I said I get about 
50MB/s with multiple dds running, around 30 with a single thread.
(dd if=/dev/zero of=/dev/daX bs=1M count=n)

Writing to local disk at the target gives me like 300MB/s

I have also been experimenting with different burst lengths, queue 
depths and so no with no noticeable difference.

I have also tried iozone and dd on both ZFS and UFS, similar results, 
40MB/s and peaks at 50MB/s. So I figure it has to have something to do 
with my iscsi setup.

Comment "Global section"
NodeBase "dc3"
PidFile /var/run/istgt.pid
AuthFile /usr/local/etc/istgt/auth.conf
LogFacility "local7"
Timeout 30
NopInInterval 20
DiscoveryAuthGroup AuthGroup9999
MaxSessions 16
MaxConnections 4
FirstBurstLength 262144
MaxBurstLength 1048576
MaxRecvDataSegmentLength 262144

Comment "Internal Logical Unit Controller"
AuthMethod CHAP Mutual
AuthGroup AuthGroup10000
Portal UC1

Comment "T1 portal"
Portal DA1 ip:3260

Comment "V1 group"
InitiatorName "dc1"
Netmask ip/24

TargetName V1
Mapping PortalGroup1 InitiatorGroup1
AuthGroup AuthGroup1
UseDigest Auto
UnitType Disk
QueueDepth 64
LUN0 Storage /dev/zvol/store/v1 Auto

dc3 {
         authmethod      = CHAP
         chapIName       = id
         chapSecret      = pass
         Initiatorname   = dc1
         TargetName      = dc3:V1
         TargetAddress   = ip:3260,1
         MaxConnections  = 4


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