Native Multi-Pathing Settings for ESXi 5.0 and EMC SAN’s

29 03 2014

The other week I was doing a Root-Cause Analysis for a client that had a Data Unavailability outage when they were doing a SAN Upgrade. They had a EMC SAN, ESXi Host running 5.0 and also Pernix Data in the environment. So as I put the puzzle pieces together so did each of the manufactures of each of the products no surprise they all came back and said everything looks good we see where X happened and so it has to Y that did not handle things correctly. Not slamming anyone here it is just the nature of the beast really each component ties into the other component and each one has their own variables and best practices.

I literally started by digging through the VNX SP logs to see the sequence of the events from both Storage Processors and I saw where the disconnects happened on A and disconnects happened B. The timing was really close but there was still ample time between failovers of the SP’s. Next I looked at Pernix Data because I had not worked with Pernix in detail before I had to do a little research to figure out the inner workings not to mention I had their RCA in hand in pretty short order that spelled out what they saw from their side. So short story here is Pernix while it essentially inserts its pathing into VMware it literally takes whatever was set on the host and then sets is to that in Pernix. For instance if you have NMP set to RR then Pernix is going to show as PRNX_PSP_RR. My co-worker has an in-depth blog on Pernix here. Anyhow, I was able to quickly eliminate Pernix from the cause of the issue. So that left me with VMware and EMC to try and figure out what happened. So before I even went to VMware to see what they saw in Pernix’s RCA they showed that there was a APD- All Paths Down. How could that be? I just looked through the EMC logs and I could see where EMC failed over from SPA to SPB and I could see the paths come up. I was now really puzzled and even more intrigued. I could hear this little voice going hey remember there was that deal with 5.0 and EMC SAN’s back a few years ago something about pathing what the heck was it?

So I started looking for EMC Best Practices for VMware and I also consulted VMware’s Best Practices so see what they recommended for ESXi 5.0. Hmm now here is the funny thing both Best Practices made mention of ESXi 4.1, 5.1 and 5.5 NMP being set to Round Robin (RR) uhh ok where is 5.0? I did a lot more digging and reading and then I started scouring the internet for things I may have missed then I remembered Chad Sakacc made blog post about it so off to Chad’s blog I went here. Which confirmed what I had swirling around in my head back on the CX4 and VNX line if you used ESXi 5.0 the recommended setting was setting NMP to fixed. So I went back to EMC and asked their support to confirm whether this was still true on the VNX2 line and they confirmed that yes FIXED is still recommended for ESXi 5.0. So I saw a chart once that made it idiot proof so I tried to recreate that here.

ESXi Version VNX Software Revision NMP Recommended NMP PSP Selection
ESXi 4.1, 5.1 and 5.5 OE 31 or above Round Robin
ESXi 4.0 and 5.0 OE 31 or above Fixed

I will say that this only shows for VNX but the same does hold true for CX4 and VNX2 as well. One other thing you must ensure is that ALUA is enabled on the Array. Which this is done by making sure that when you go to the initiator records of the particular host that it is set to Clariion and Failover Mode 4 (FOM4)(ALUA). A great deal more of information for setting your array connections to ALUA here

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2 responses

29 10 2014
Bobby

This customer has to upgrade the VNX2 again, and they happen to stumble upon a blog about it. Ha.

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29 10 2014
girardsc

Well Bobby glad this blog could be of some help 🙂

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