A while ago I posted an article on LUN connectivity issues with Storage vMotion on EMC VNX when using VAAI we experienced.
Today I did received an e-mail from EMC they are able to reproduce our issues in their lab, which is an important step to get these issues resolved, since we can only do limited tests in our production environment. Great news to start the weekend. Will update again when I get more details on this.
Today I received a tweet from Chad Sakac, SVP Global SE at EMC, that he will be discussing some of the questions and concerns I raised in my blog post Challenges when upgrading environment with EMC CX4 to vSphere 5 and mixed CX4/VNX environment in next weeks Chad’s Choice WebEx, and in a blog post on his Virtual Geek blog.
Subjects for this call will be: Continue reading
Yesterday I wrote an article on issues when using a combination of CX4 and VNX in a vSphere 5 environment since ESX5 does not support on VAAI according to VMware and the VNX does. Simple solution would be to disable VAAI on all ESX5 hosts, but in that case your VNXes would also loose VAAI. Victor Forde pointed me to a blog post by Chris Wahl titeled “Forcing the NMP Plugin for Microsoft Clustering LUNs on vSphere” (good post by the way)
When reading this article, I realized you can not only use the array vendor and model strings to assign the VAAI filter driver to an array, but you might also be able to use the location (the combination of adapter, target, channel and LUN) for a device to assign the VAAI filter and VAAI Plugin to a specific array.
In short, you would need to remove the default VAAI filter and VAAI plugin rules for vendor=DGC and model=* and replace them by claim rules for based on the location where you would use the target identifier to filter on, for the array that would need to have VAAI enabled.
Unfortunately I don’t have a VNX in my lab (Someone at EMC that wants to trade my VNXe and a case of beer for a VNX? 😉 ) so I am not able to test if this would really do the trick. Continue reading
Yesterday my good friend Gabrie van Zanten from Gabes Virtual World asked the following question on twitter:
My first reaction was “Why would Gabe want to disable VAAI on a per array basis isn the first place?” so I asked.
His answer was pretty simple and straight forward. He was working on an environment where ESX5 hosts had both EMC CX4s and VNXes connected, and VAAI was not supported on vSphere 5 for CX4, so he had to disable VAAI for the CX4’s and wanted to leave it on for the VNXes. Continue reading
The last few weeks I have been working on some serious issues in an environment where we used vSphere 5 with an EMC VNX storage array. All seemed to run fine, but whenever we started a Storage vMotion, we noticed all kinds of strange errors we where not expecting at all.
We saw messages regarding write-quiesced VMFS volumes, we lost paths. and in some cases, the Storage vMotions did not complete at all.
During these Storage vMotions we noticed datastore latency peaked at more then 5 seconds on the source and destination LUN’s.
Recently I saw some unexplained LUN trespasses on an EMC VNX that is used in a vSphere 5 environment where we use VAAI.
Since we use pools on the VNX, it is advised to keep a LUN on the owning SP, to prevent unnecessary traffic over the internal bus between SPA and SPB. EMC says:
Avoid trespassing pool LUNs. Trespassing the pool LUNs to another SP may adversely affect performance. After a pool LUN trespass, a pool LUNs private information remains under control of the original owning SP. This will cause the trespassed LUNs I/Os to continue to be handled by the original owning SP. When this happens both SPs being used in handling the I/Os. Involving both SPs in an I/O increases the time used to complete an I/O. Continue reading