Unmount VMFS Datastore

With all the wicked-cool new functions in vSphere 5, one of the most understated but highly functional lies with the ability to unmount an iSCSI share. Seemingly a simple function, this has not been available in non-vSphere 5 hosts until now.

The problem I have faced in the past is that there is a need to remove iSCSI stores from an ESXi host. In those rare instances, I have needed to migrate some VMs off of a SAN while keeping other VMs on the same SAN (ex: moving a development SAN to another site). svMotion handles the hard work of moving the VMs to the new datastores (easy-peasy, right?). However, unlike an NFS share, a VMFS share could not be unmounted. I ran into 2 options to remove the share:

1) Right-click the datastore and select “Delete”!


Uh… the point of this is to not delete these VMs!

2) Remove the initiator IP address, remove access to the ESXi host initiators via the SAN interface, vMotion VMs to other hosts (if you’re lucky), and reboot the host.

– Host downtime, SAN maintenance (which, yes, I know initiators not being used should be cleaned up… but not as a requirement to save my VMs), host downtime, etc… I can add a datastore live, why not remove it live?!


To my surprise this morning, while removing some iSCSI stores after some over-the-weekend SAN migration, I was presented with a new option via vSphere 5!

Unmount Datastore - vSphere 5

Following this new function leads me to a functional check to ensure that the unmount requirements are green and good to go:


Now, the downside to this procedure is that in my environment, I have a couple non-DRS clustered hosts (thank you Oracle VMware licensing) that I am unable to take offline to upgrade to ESXi 5.0 right now. So, the same iSCSI volumes are available on both ESXi 4.1 and 5.0 hosts. Thus, the unmount process is only partially useful. Due to those darn ESXi 4.1 hosts, I still need to delete the datastore to get rid of the iSCSI volume!

Unmount Datastore - vSphere 5 and 4.1

Thanks Oracle Licensing!

Lucky for me, I do not have any VMs to save on the datastore!

This was a great way to start a Monday morning! I look forward to being able to unmount VMFS volumes as necessary… once everything is up to vSphere 5.0!



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