vSphere 6.5 – Creating Shared VMDK’s for Clustering Services.
(SQL Failover Cluster in VMware using VMDK’s Part 1)
Creating a VMDK to share between multiple guests using Windows Failover Clustering and possibly SQL Clustering is a very straight forward task, but there are a few “Gotcha’s” to consider.
-You cannot use a Thin Provisioned VMDK. You will have to be more aware of sizing if you worried about conserving space on your shared storage device, and your device isn’t doing a good job with compression / deduplication for whatever reason.
-You cannot Snapshot a Shared VMDK. This may present a challenge for backing up and rolling back volumes, and you must be prepared (Note: My favorite backup product, Veeam, has support for backing up WFC’s as of 9.5 u3).
First you are going to have to create a new SCSI controller for the VM Guest. When you do that, make sure you are using “LSI Logic SAS” and change SCSI Bus Sharing to Virtual.
Next when creating the Shared VMDK, you will have to:
-Change Disk Provisioning to Thick Provision Eager Zeroed
-Change Sharing(*) to Multi-writer
-Change the Disk Mode to Independent – Persistent” to keep any Guest snapshot off the VMDK’s back.
(Setting it to Independent excludes the disk from snapshot. Persistent avoids creating a delta log, while Non-Persistent creates the log, but throws it away after reboot).
-Change iSCSI controller to the new iSCSI controller you created (1 most likely). You cannot use the default iSCSI controller Zero.
Bonus Points: Creating a new Datastore for your “Shared” disks in the cluster and remapping the disks to be created there will help you manage them better.
Thank you for reading. In part two we will install Windows Failover Clustering in Server 2016 and configure the new shared disks.