MPIO expected results? SAS different to iSCSi

Radian

Member
Mar 1, 2011
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iscsi mpio.PNG sas mpio.PNG
Hi,

Using a dual backplane JBOD (SuperMicro) and server 2012R2, what is the expected result of enabling MPIO on SAS disks? I have a host with iSCSi and SAS initiators, both with dual paths (two networks for iscsi & dual port HBAs to SAS drives in JBOD), however, MPIO appears different between the two interfaces.

iSCSi MPIO shows me two paths per disk but SAS shows me only one path. Is this normal, should I expect two paths for SAS connected drives?

Cheers.
 

cesmith9999

Well-Known Member
Mar 26, 2013
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SAS MPIO depends on your backplane to your disks.

SAS disks have 2 channels. A and B. if you have a single channel board. then MPIO is useless. if you have a dual channel backplane then you will get ~ 50% increase reliability and a theoretical increase in throughput (depends on how many disks and what type). and how you have it hooked to your SAS HBA.

please give us your backplane model number and your disk types plus a diagram as to how the cables are connected.

Chris
 

Radian

Member
Mar 1, 2011
59
5
8
Backplane is the dual port version from supermicro, JBOD chassis is SC837-e26.

Disks are a mixture of Hitachi and Seagate 300GB SAS drives.

Connections are as per the attached picture, except I have a 9300-8e HBA with two ports not 4.

Port connections.png

Given my config, would you expect to see two paths in the drive's MPIO properties as is seen in iSCSI drives?
 

cesmith9999

Well-Known Member
Mar 26, 2013
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in the MPIO dialog. on the 2nd tab, is the SAS MPIO checked?

will require a reboot

Chris