Thursday, 3 August 2017

Upgrading VMFS 5 datastore to VMFS 6

Recently got request to create a Monster VM wherein the CPU and Memory requirements was higher but the disk requirements was way to high when compared with other Virtual Machines,after carefully considering the current datastore space utilization I requested my Storage team to give me an additional LUN so as I can go ahead and create a new datastore and fit this new Monster Virtual Machine.

While working on this request I realised that this new datastore will be VMFS6 and I can considered this as an opportunity to upgrade other VMFS5 datastore to VMFS6 so followed below steps to upgrade VMFS5 datastore to VMFS6. 

But before we proceed further and understand the prerequisites and the steps involved during the upgrade process let's understand VMFS6 which is new file system in VMware vSphere 6.5 which supports 512e advanced format drive and provides automatic UNMAP ensuring freed blocks information is passed to the backend storage device.

Ensure all your ESXi hosts and the vCenter Server are already upgraded to VMware vSphere 6.5, if ESXi host's is not upgraded to vSphere 6.5 it will loose connectivity to the new VMFS6 datastore. In my case all the ESXi on which the old VMFS5 datastore was mounted were already upgraded to vSphere 6.5.


The plan was to upgrade both my VMFS5 Datastore Datastore 1 and Datastore 2 running in a Storage DRS Cluster to VMFS6, both the datastore were running Production Virtual Machines so I had to be extra cautious will performing this activity, so proceeded further with creation of new datastore Datastore 3 VMFS6 and started storage vMotion to migrate all the Virtual Machines from Datastore 1 to newly created VMFS6 Datastore 3.

This was the most boring step during the upgrade because the Virtual Machines took their own time to migrate but at the same time I had to pay a lot of attention when the migration was happening ensuring the Virtual Machines are successfully migrated, I migrated 2 Virtual Machines at the same time because there were more than 30 Virtual Machines running on this datastore however it's best if we do it one Virtual Machine at a time.

Note : Another way of evacuating Datastore 1 is to put it in Maintenance Mode and let the migration happen automatically if it is part of Storage DRS Cluster.

Once all my Virtual Machines were successfully migrated from Datastore1 to newly created VMFS6 Datastore 3, it was time to put Datastore 1 in maintenance mode and move it out of the SDRS cluster but before doing so it's wise to check if there are no other files on this datastore as sometime you may see some Orphaned Virtual Machines folders residing on that datastore and if that is the case make sure to move them one by one to the new datastore.

After cross verifying the datastore files Datastore 1 entered the maintenance mode and unmounted it from all the ESXi hosts and then deleted it, do not proceed further with the unmount / deletion process if your datastore is not empty.

Another important point worth considering before you delete your datastore is to check datastore backing LUN and make sure you take screenshot or remember the name of that LUN because we need it later when creating the datastore.

It was time to create a new datastore wherein I used the same name Datastore 1 VMFS6 and left all other options (Block Size, Space Reclamation Granularity and Space Reclamation Priority) unchanged.

Mounted it to all the ESXi hosts and did a quick rescan on each ESXi hosts and then moved all the Virtual Machines back to this newly created Datastore, used same steps to upgrade Datastore 2 as well.

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