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vmware fixed / last-used / round-robin multipathing connected to 3par array.

StuartA46
Frequent Advisor

vmware fixed / last-used / round-robin multipathing connected to 3par array.

VMware people:

 

This is a VMware question from a Storage Guy.

 

We recently stood up a SQL Server VMware Farm connected to a HP 3PAR array.  Each ESX Server has 2 x HBAs to the SAN, so that they see 4 x "paths" to the Array (2 paths on each HBA / fabric).

 

They SQL Server VMware Farm hosts multiple SQL Server "Clusters" on multiple ESX hosts running vSphere 5.1.  MicroSoft Clustering on vSphere 5.1 requires that you use RDM as Cluster Disks, and furthermore you must access them with "fixed" ESX multipathing, whatever that's called.  It has SCSI interlock implicaitons.  If they were running vSphere 5.5, they could use VMFS files for Microsoft Cluster cluster disks.

 

So, they designed the entire VMware Farm to use all RDMs for All data volumes.  (C: and D: drives of individual instances are VMFS.)  And they ALL use "fixed" or "last-used" multipathing.  The end result is that they beat up on one path on one HBA to the Storage Array and don't even use the other paths at all. 

 

Can they set up their ESX systems so that the MSCS cluster volumes are RDMs with "fixed" or "last-used" multipathing, and the rest of the volumes (the data RDMs) are "round-robin".  At a minimum that would improve performance.

 

    Stuart

 

 

P.S. This thread has been moved from ESX to ESXi. -HP Forum Moderator

2 REPLIES
indus
HPE Pro

Re: vmware fixed / last-used / round-robin multipathing connected to 3par array.

Hi Stuart,

 

I would state that RDM is for clustering (Quorum disk), for SAN management tools (e.g. backup, snapshots), Otherwise use VMFS. By this the Limitation of RDM will not reach.

Also For Database Layout: Follow same guidelines as physical - separate LUNs for data and redo/log and it Should be joint effort between DBA, VMware, and Storage admins to get best out of it.

Click here for the Performance Characterization of VMFS and RDM Using a SAN.

 

Hope this will give a insight on how to go about.

 

Thanks,

I work for HP
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Jan Soska
Honored Contributor

Re: vmware fixed / last-used / round-robin multipathing connected to 3par array.

We use RR as mutlipathing. It is generally question of what storage vendors recomends, as I know HP recomends RR for EVA and 3par..

 

jan