I'm seeing seriously degraded performance with round-robin SAS
multipathing. I'm hoping you guys can help me achieve full throughput
across both paths.
My System Config:
OpenSolaris snv_134
2 x E5520 2.4 GHz Xeon Quad-Core Processors
48 GB RAM
2 x LSI SAS 9200-8e (eight-port external 6Gb/s SATA and SAS PCIe 2.0 HBA)
1 X Mellanox 40 Gb/s dual port card PCIe 2.0
1 x JBOD: Supermicro SC846E2-R900B (Dual LSI SASX36 3Gb/s Expander
Backplane, 24 Hot Swap drives)
22 x Seagate Constellation ES SAS drives
Performance I'm seeing with Multipathing Enabled (driver: mpt_sas):
With only one of the two paths connected:
1 drive connected: 137 MB/s sustained write, asvc_t: 8 ms
22 drives connected: 1.1 GB/s sustained write, asvc_t: 12 ms
With two paths connected, round-robin enabled:
1 drive connected: 13.7 MB/s sustained write, asvc_t: 25 ms
22 drives: 235 MB/s sustained write, asvc_t: 99 ms
With two paths connected, round-robin disabled, pin half the drives to
one path (path A), the other half of the drives to the other path (path B):
22 drives: 2.2 GB/s sustained write (1.1 GB/s per path), asvc_t: 12 ms
Multipath support info:
mpathadm show mpath-support libmpscsi_vhci.so
mpath-support: libmpscsi_vhci.so
Vendor: Sun Microsystems
Driver Name: scsi_vhci
Default Load Balance: round-robin
Supported Load Balance Types:
round-robin
logical-block
Allows To Activate Target Port Group Access: yes
Allows Path Override: no
Supported Auto Failback Config: 1
Auto Failback: on
Failback Polling Rate (current/max): 0/0
Supported Auto Probing Config: 0
Auto Probing: NA
Probing Polling Rate (current/max): NA/NA
Supported Devices:
Do I have to add an entry to this section of /kernel/drv/scsi_vhci.conf
(if so, how do i find the information to add)?:
#
# For a device that has a GUID, discovered on a pHCI with mpxio enabled,
vHCI access also depends on one of the scsi_vhci failover modules
accepting the device. The default way this occurs is by a failover
module's "probe" implementation (sfo_device_probe) indicating the device
is supported under scsi_vhci. To override this default probe-oriented
configuration in order to
#
# 1) establish support for a device not currently accepted under
scsi_vhci
#
# or 2) override the module selected by "probe"
#
# or 3) disable scsi_vhci support for a device
#
# you can add a 'scsi-vhci-failover-override' tuple, as documented in
# scsi_get_device_type_string(9F). For each tuple, the first part
provides basic device identity information (vid/pid) and the second part
selects the failover module by "failover-module-name". If you want to
disable scsi_vhci support for a device, use the special
failover-module-name "NONE".
# Currently, for each failover-module-name in
'scsi-vhci-failover-override' (except "NONE") there needs to be a
# "misc/scsi_vhci/scsi_vhci_<failover-module-name>" in 'ddi-forceload'
above.
#
# " 111111"
# "012345670123456789012345", "failover-module-name" or "NONE"
# "|-VID--||-----PID------|",
# scsi-vhci-failover-override =
# "STK FLEXLINE 400", "f_asym_lsi",
# "SUN T4", "f_tpgs",
# "CME XIRTEMMYS", "NONE";
#
#END: FAILOVER_MODULE_BLOCK (DO NOT MOVE OR DELETE).
How can I get this working as expected (2.2 GB/s round-robin
load-balanced across both paths)?
Thanks in advance for your assistance!
Josh Simon
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