5 Tungsten

Re: Ask the Expert: VMware and VNX Integration Best Practices

A couple of months ago we ran into an issue where RDMs provided to an SQL cluster were very slow. Everything looked good: failover mode 4 on the VNX side and round robin on the VMware side. For RDMs the recommendation however was to set the FO policy to 1 and use MRU (or fixed, I'm not entirely sure anymore). The performance of the disks went up and the customer was happy again. I was wondering if you've encountered more database server specific settings that could improve performance. for example: what if a small VNX 5200 is only used for SQL 2008 and 2012, is there some tweaking we can do on the VNX cache or disk allignment or number of paths from the host to the array. Is 4 paths on VNX always the best, then why is 2 the best practice when used on a VMAX? Do these settings have something to do with VMware. And what about queue depth, execution throttle and perhaps other settings on the HBAs of a host. Are there any VMware specific tweaks concerning this queue depth that we need to consider?

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