tuning performance for tgtd and open-iscsi

[Jelle de Jong]

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Hello everybody,

How can I tune the debian 2.6.32-5-amd64 kernel for better performance
with open-iscsi and/or the debian 3.2.0-4-amd64 kernel on the tgtd target?

We got a tomcat application that uses a lot of small small files and
an virtual machine with local storage the performance is fine, but if
the virtual machine uses a disk over iscsi its becomes unusable. We
tried xfs and ext4 with noatime, but so far no real improvements.

When I look with iotop at the kvm process the vm uses max 4 a 5 MB/s
disk access witch should be fine, (it handles 40/70MB/s with about 12
vms and nethogs shows 40MB/s to the iscisd)

# sysctl --all
http://paste.debian.net/hidden/c5d171b5/

# iscsiadm --mode node --targetname iqn.2012-10.nl.exmp:storage.iscsi0
- --portal 192.168.35.6:3260
# BEGIN RECORD 2.0-873
node.name = iqn.2012-10.nl.hivos:storage.iscsi0
node.tpgt = 1
node.startup = automatic
node.leading_login = No
iface.hwaddress = <empty>
iface.ipaddress = <empty>
iface.iscsi_ifacename = default
iface.net_ifacename = <empty>
iface.transport_name = tcp
iface.initiatorname = <empty>
iface.bootproto = <empty>
iface.subnet_mask = <empty>
iface.gateway = <empty>
iface.ipv6_autocfg = <empty>
iface.linklocal_autocfg = <empty>
iface.router_autocfg = <empty>
iface.ipv6_linklocal = <empty>
iface.ipv6_router = <empty>
iface.state = <empty>
iface.vlan_id = 0
iface.vlan_priority = 0
iface.vlan_state = <empty>
iface.iface_num = 0
iface.mtu = 0
iface.port = 0
node.discovery_address = 192.168.35.6
node.discovery_port = 3260
node.discovery_type = send_targets
node.session.initial_cmdsn = 0
node.session.initial_login_retry_max = 8
node.session.xmit_thread_priority = -20
node.session.cmds_max = 128
node.session.queue_depth = 32
node.session.nr_sessions = 1
node.session.auth.authmethod = None
node.session.auth.username = <empty>
node.session.auth.password = <empty>
node.session.auth.username_in = <empty>
node.session.auth.password_in = <empty>
node.session.timeo.replacement_timeout = 480
node.session.err_timeo.abort_timeout = 15
node.session.err_timeo.lu_reset_timeout = 30
node.session.err_timeo.tgt_reset_timeout = 30
node.session.err_timeo.host_reset_timeout = 60
node.session.iscsi.FastAbort = Yes
node.session.iscsi.InitialR2T = No
node.session.iscsi.ImmediateData = Yes
node.session.iscsi.FirstBurstLength = 262144
node.session.iscsi.MaxBurstLength = 16776192
node.session.iscsi.DefaultTime2Retain = 60
node.session.iscsi.DefaultTime2Wait = 5
node.session.iscsi.MaxConnections = 4
node.session.iscsi.MaxOutstandingR2T = 1
node.session.iscsi.ERL = 0
node.conn[0].address = 192.168.35.6
node.conn[0].port = 3260
node.conn[0].startup = manual
node.conn[0].tcp.window_size = 524288
node.conn[0].tcp.type_of_service = 0
node.conn[0].timeo.logout_timeout = 15
node.conn[0].timeo.login_timeout = 15
node.conn[0].timeo.auth_timeout = 45
node.conn[0].timeo.noop_out_interval = 15
node.conn[0].timeo.noop_out_timeout = 30
node.conn[0].iscsi.MaxXmitDataSegmentLength = 0
node.conn[0].iscsi.MaxRecvDataSegmentLength = 262144
node.conn[0].iscsi.HeaderDigest = None
node.conn[0].iscsi.DataDigest = None
node.conn[0].iscsi.IFMarker = No
node.conn[0].iscsi.OFMarker = No
# END RECORD

Kind regards,

Jelle de Jong
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