Info on iSCSI settings (ESX 4/MSA1510i/Procurve)

[Antonio_73]

I'm testing iSCSI configurations, and I'd like if someone can enlight me on some questions.

Which is the importance of setting flow control or jumbo frames on iSCSI (we never set them usually)?
VMware asks for dedicated ethernet cards on iSCSI (one port = one iSCSI vlan). Is it a simple advice, or a MUST be option? I have eight GB cards, and I'd love to pool them for performance and reliability, mixing iSCSI vlan with other vlans.

Thanks,

Tonino

[wobbe]

If you have a dedicated storage network I would enable jumbo frames and disable flow control. Don't go mixing jumbo frames (MTU 9000) and "normal" frames. (MTU 1500)

[Steven Clementi · Accepted solution]

The short answer is... No. It is not a "must".

Be forewarned though that it is likely you will have performance issues if you are sharing a network.

You have 8 1GB pipes potentially... what would it be to lose 2GB to separate out your iSCSI traffic?


Oh, btw... the recommendation for vMotion is the same, totally separate network at 1GB..... oh yea... you doing Fault Tolerance? You need another separate 1GB network (this I would consider a must have in a low-medium to higher environment).

You can get away with sharing in a small environment, but sharing will always lead to performance issues.


Optionally... if you want to have the "reliability" or some type of backup, you could still configure all your cards in a vswitch and then tell your VMNetwork to use 4 or 6 of them primarily and the other 2 as a backup and for your iSCSI, use the 2 primarily and the others as a backup.


Steven

[Uwe Zessin]

> for your iSCSI, use the 2 primarily and the others as a backup.

The traditional 'active/standby adapter teaming' does not work with the software iSCSI initiator on ESX4. The SWI cannot be bound to a VMkernel port (vmknic) that is connected to a port group with multiple pNICs attached.

Instead you create a second VMkernel port with a second IP address (can be on the same IP subnet) and connect it to a second port group that has a different pNIC attached. Then, bind the SWI to that second vmknic.

[Antonio_73]

Actually, I would use 4 dedicated ports for iSCSI (MSA1510i has 4 ports) and 4 ports for all the remaining traffic (Internet, intranet, vmotion).
So I can have two vSwitch of 4 ports each one or one bigger vSwitch of 8 ports.
I'd like to use all ports in the same vSWITCH, giving dedicated ports for iSCSI (1 fixed port for accessing each MSA adapter, with no spare port), but I'd like the possibility of mixing ports for emergency situations or migrations or temporary change of ports (which I can do better with a 8 ports switch).

[Antonio_73]

It looks like my "thoughts" about jumbo frames and dedicated cards have no sense in my environment.
It seems MA1510i MTU cannot be changed, so there is no particular reason to give jumbo MTU to ESX vswitch and portgroup.

Tonino

[Steven Clementi]

Every iSCSI solution does not require the same settings.

For Lefthand Networks, these settings might make all the difference in the world.

The MSA1510i is nothing like a P4300.


Steven

[Antonio_73]

What happens when I give two portals (for redundancy) to each volume?
Can MSA1510i force the best portal for performance reason? In such a case, may I use 4 portals on for different iSCSI ports?

When using a second controller, also two iSCSI ports must be added.
Will the second controller only use these two iSCSI ports only, or the usage of all 4 ports is shared between controllers?

Is there any clear document about preferred paths, SCSI and iSCSI constraints?

Thanks!