There are several ways to get more disk storage available for your VMs running on VMware ESX. Adding an extra datastore is an option, but having multiple datastores creates an extra administrative overhead since you now have multiple datastores to monitor.
Many SAN administrators will face this challenge from time to time: certain hosts need to start using new storage ports. Reasons vary, but in the EMC Clariion/VNX world this might happen because it’s decided to dedicate the mirrorview ports to mirrorview only instead of allowing hosts to use these ports as well. Obviously having dedicated replication ports will improve replication performance and for synchronous replication this will also improve the production host performance since the write acknowledgement from the remote array will be quicker and the extra latency is limited to a minimum.
So you end up wanting to free the SPA1 and SPB1 ports (most Clarrions) or SPA0 and SPB0 (VNX). But disalowing hosts to use these ports means they will loose access to these paths. This just might be disruptive! Or not?
According to EMC this “adaptive queue depth” setting is not yet supported (June 2013). The full article can be found on this link. It is known as Primus solution id emc279718.
My advice would be not to use this setting until EMC certifies this setting for use with their arrays.
The exact Article is as follows:
| What is the recommended LUN queue depth throttling in VMware ESX/ESXi? | |
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| OS: VMware ESX / ESXi Product: CLARiiON / Symmetrix and I assume VNX as well |
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| According to Engineering, enabling the adaptive queue depth algorithm is NOT documented in the Host Connectivity Guide or the EMC Support Matrix. The recommendation is to use the default setting which is disable adaptive queue depth. Additional checks with E-Lab VMware quality engineers, E-Lab testing is done with the default setting. |
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| See emc274169 for additional information and or changes. Also see these two documents on support pages support.emc.com or Powerlink.Using EMC VNX Storage with VMware VsphereUsing EMC Clariion Storage with Vmware Vsphere & VMware Infracture Version 4.0 | |
Techs focussed on EMC will know “EMC USM” for its use in upgrading storage arrays like Clariion and VNX as well as disk firmwares and installing enablers, but it can be used for other purposes as well.
Gearoid Griffin, a fellow EMC Elect 2013 member, wrote a nice article about it. Go have a look, I find it very interesting!
You can find his article on https://community.emc.com/people/GearoidG/blog/2013/04/04/other-useful-features-of-usm.
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