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BrennanB
Contributor
Contributor

Vmotion and ISCSI traffic sharing switch

We currently have a Cisco switch that is dedicated to vmotion traffic for our 5 esx hosts. I am adding a Infrant 3200 NAS for ISCSI storage to our envrionment and wondering if it would be best to configure our hosts to run ISCSI traffic over this same switch? Would this cause issues with vmotion?

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Stu_McHugh
Hot Shot
Hot Shot

I have a Cisco 4948 and I run iSCSI and ESX traffic in the same switch however there are conciderations you should look at. I have vLAN'd my iSCSI traffic away from the regular traffic. Also the back plane of the switch should be reasonable enough to cope with the traffic.

Stuart

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mittim12
Immortal
Immortal

I would definitley isolate my iSCSI traffic away from everything else but it shouldn't cause you any problems.






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MattG
Expert
Expert

So long as when Vmotioning and operating iSCSI at peak dont cause network packet latency then you should be fine.

You could test this by running IOMeter on a couple of VMs that are on the iSCSI network and then perform a VMotion of another VM at the same time. Take a look at your network perf numbers via the switch and see if there was any latency or drop packet issues.

-MattG

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AntonVZhbankov
Immortal
Immortal

The same vSwitch can be used, but add another NIC for iSCSI to separate traffic.


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jsnavely
Contributor
Contributor

The Dell switch, if it's still in use, was configured with VLANs for both vmotion and iSCSI. It sounds like you may have ditched that switch though.

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crescendas
Enthusiast
Enthusiast

Since we usually enable jumbo frame of 9000 for iSCSI traffic. Will this affect vMotion traffic?

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BenConrad
Expert
Expert

What kind of cisco switch?  If it's a fixed switch vs modular my first suggestion would be to buy another switch and setup a LACP between the two.  You really don't want that single switch to die and you lose all your storage.  If it's a modular switch (like 6500) you should be in good shape with dual-SUPs.

You should be able to get away sharing vMotion with iSCSI.  With 5 hosts you should have enough bandwidth on the switches.  We have a larger iSCSI env and we run only iSCSI on a set of switches. Even with this configuration we see the ASICs on the Cisco dropping frames.  It's possible if you are doing a database backup and doing a vMotion at the same time the Cisco may drop some frames but TCP/IP will take care of the retransmission and your hosts will be happy.

Ben

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rickardnobel
Champion
Champion

crescendas wrote:

Since we usually enable jumbo frame of 9000 for iSCSI traffic. Will this affect vMotion traffic?

No, they will be able to work together on different MTU sizes, see this for some explanation.

What otherwise is most important is how your VMnics (physical nic ports) are set up?

My VMware blog: www.rickardnobel.se
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