VMware Cloud Community
GBDickinson
Contributor
Contributor

Adding free space on LUNs to a datastore

Hi everyone,

I've inherited an ESX 3.51 environment, and while I know more than the average Cisco nerd about ESX Smiley Happy I'm not nearly the expert that some here are, so if I use incorrect terminology, please excuse my igorance.

I've come to the realization that I'm running low on disk space in my Datastore.  This datastore consists of 6 500 gb LUNs all configured as extents in a single datastore.  However, I noticed that the LUN capacity and the Partition size didn't match up - I was missing 100 gigs per LUN, as shown below:

VMGuestsProps.JPG

So I thought, "Excellent, I'll just format up six 100 gig partitions, add them to the datastore, and bingo! 600 gigs more disk space.  However when I click that "Add Extent" button at the bottom and choose a LUN with 100 gigs of free space, I get this screen (see the highlighted part to see why I'm scared to go past this point):

AddExtent.JPG

This seems to indicate that if I proceed and add the 100 gigs of free space I will lose my existing 400 gig partition, which since that partition is an extent on my datastore, it would be logical that the entire datastore (and all my VMs) will go away if that extent is deleted.  That's what's referred to as a "resume-generating event" :smileygrin:

So, I reach out to the community for answers.  Am I reading this right?  Is there a way to "reclaim" this 600 gigs of disk space without losing everything else?

Thanks in advance for any help you all can be.

Reply
0 Kudos
3 Replies
a_p_
Leadership
Leadership

I'm afraid you won't be able to use the free space in any supported way. With the extents you are limited anyway and creating an additional datastore on a LUN is not supported by VMware (1 LUN -> 1 Datastore).

If you have free disk space on the storage system, I'd suggest you consider to create new LUNs (max. 2TB minus 512 Bytes) and migrate the VM's over to these LUNs to get rid of the extended datstore.

André

GBDickinson
Contributor
Contributor

Really, so I can't have multiple VMFS partitions on the same LUN?  How do you handle (for example) a 10 terabyte local disk that has to be split into 2 terabyte chunks?

Reply
0 Kudos
a_p_
Leadership
Leadership

How do you handle (for example) a 10 terabyte local disk that has to be split into 2 terabyte chunks?

You can't do this (supported) with VMFS3. What you need to do, is to present smaller LUNs and/or - in case of local RAID - split the RAID set into multiple logical volumes, which are then presented to the OS as individual disks.

In order to use LUNs larger than 2TB you need to upgrade to VMFS5, which was introduced with vSphere 5. VMFS5 supports LUN sizes of up to ~64TB.

André

Reply
0 Kudos