DMP, MPIO, MSDSM, SCSI-3 and ALUA configuration settings
Ok, I'm somewhat confused and the more I read the more confused I think I'm getting.
I'm going to be setting up a 4 node active/active cluster for SQL. All of the nodes will have 2 seperate fiber channel HBAs connecting through 2 seperate switches to our NetApp. The NetApp supports ALUA, so the storage guy wants to use it. It is my understanding that I need to use SCSI-3 to get this to work. Sounds good to me so far. My question is, do I need to use any of Microsoft's MPIO or MSDSM? This is on Win 2008 R2. Or does Veritas take care of all of that?
Also, I read that in a new cluster set up, only connect 1 path first and then install and then connect the 2nd path and let Veritas detect it and configure it. Is that accurate?
Any info or directions you can point me will be greatly appreciated. Thanks!
Hi scogeb, The Symantec DMP
The Symantec DMP requires that the MIcrosoft Multipathing feature be installed. This feature from Microsoft installs the frame work for MPIO and the Microsoft DSM.
Our DMP solutions installs our developed DSMs for the arrays that we support. The Microsoft DSM is designed genericaly to work with many different arrays and the Symantec DSMs are designed and optimized to work with specific arrays.
Symantec's DMP does support many NetApp arrays running in ALUA mode. Please check our HCL to ensure that your specific array is listed as supporting mode "A/A-A". I do not know if the Microsoft DSM support ALUA mode or not. You would need to check with Microsoft for the details on what their DSM supports.
As best practice, if the disks have data on them, then single path your environment before install or uninstalling DMP. This will avoid data corruption that can be caused by the drives being accessible via multiple paths without a DMP software controlling the flow of I/O to the disks.
If there is no data on the volumes, then you can have multiple paths to the storage. However, it is suggested to format (quick or full) after installing DMP and rebooting to ensure that the filesystem is clean before putting data on the volumes.