ISCSI on HP-UX 11.31

[andrei_cupa]

Hello all,

I'm trying to configure an HP LeftHand on HP-UX 11.31. I configured a NORMAL trunk with 2 NIC's using APA, but this only helps me in case of failover. Is there a way for using more than 1 NIC for multipathing to the same LUN?

Thanks in advance.

[rick jones]

I cannot speak to the LeftHand, but broadly speaking, APA offers the ability to select from several different packet scheduling algorithms - among them are those based on MAC/Ethernet address, IP address and TCP port number.

The inbound path is controlled by the packet scheduling algorithm being used by the switch.

So, to get more than one NIC used to a LUN, that LUN needs to be reachable via either more than one MAC address, or more than one IP address, or more than one TCP connection. Then APA will spread the write traffic across multiple NICs in the aggregate. For read traffic (aka inbound from the perspective of the host) it will depend entirely on the switch.

[Dave Olker]

To add onto what Rick said, you need multiple TCP connections between the iSCSI initiator and the iSCSI target if you hope to take advantage of multiple physical links in an APA aggregate.

HP-UX currently only supports the Software-based iSCSI Initiator. I don't know enough about how iSCSI works to know if it's possible to configure multiple TCP connections to a single iSCSI target, but looking at the iSCSI manual it states:

Connections per Session
The iSCSI Software Initiator supports one connection per session (an iSCSI session is equivalent to a SCSI I-T nexus).

Again, I don't know if by "one connection per session" that equates to "one TCP connection" or not, but I couldn't find anything iron clad in the documentation that shows how to control the number of TCP connections opened between the initiator and target.

Putting on my dusty old NFS hat, HP-UX *does* allow the ability to open multiple TCP connections between an HP-UX NFS client and an NFS server, thus allowing NFS to take advantage of multiple adapters in an APA aggregate.

Food for thought...

Dave

[Sriram Narasimhan]

I believe the current HP-UX iSCSI software initiator supports only one TCP connection per iSCSI session, so there is no LUN multipathing support.

[kjohnsonm]

"I believe the current HP-UX iSCSI software initiator supports only one TCP connection per iSCSI session, so there is no LUN multipathing support."

So just looking for an update on this post, is this restriction still true in 2013 Feb?  TIA.