Increase the size of your ISCSI VMFS

[jayjman0077]

Hello!

I've got ESX 3.5 connected to a LEFT HAND ISCSI SAN. the VMFS is on the SAN.

I want to increase the size of the VMFS, so that I can add more virtual machines to it.

Increasing the size on the SAN is no problem, but how to I get the ESX servers (I use virtual Center)

to 'see' the increase in volume size?

I assuming I just 'refresh' under 'storage' configuration, but Just want to make sure.

Is there a risk of service interruption? ---> can this be done in the middle of the day?

Thanks!

[JeffDrury]

You will need to do a 'rescan' on the ESX iSCSI adapter to get the extended partition to show up. Once you have this you can add an extent to increase the size of the datastore. The dialogue will give you an ugly message saying all data on the device will be erased or something like that but it is only referring to the new disk space that has been added not your existing partition. I think you can only have 4 extents per VMFS datastore so this isn't something you can do more than 4 times. There should not be a service interruption but I would suggest doing this after hours the first time in case any other issues come up. Also make sure you have current backups, just in case.

While it is possible to extend your current partitions I would almost recommend creating a new volume/datastore with the correct size and using vMotion to migrate VM's to the increased storage. If you are using LeftHand you can thin provision the volume and set it to a high initial size without actually occupying the disk space on your SAN. As long as you monitor the actual usage this should allow you to grow without having to deal with keeping track of VMFS extents.

[RParker · Accepted solution]

Increasing the size on the SAN is no problem, but how to I get the ESX servers (I use virtual Center) to 'see' the increase in volume size?

You don't. You can't resize VMFS volumes. You have to move your VM's, Delete the LUN, recreate the LUN of correct size, move your VM's back.

Supposedly ESX 4.0 (vSphere) wll allow you to resize, but for now no way to do it.

There is extensions but that's not recommended. That just ADDS space and tacks it on to the original system, but it exposes you to more risk, best to recreate LUNs.

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[Lightbulb]

As has been pointed out you cannot extend a VMFS datastore.

You can create new LUNs on you SAN and add them as extents to the datastore.

You can add new LUNs and create new datastores.

There is debate about which method to use, I prefer the second option.

The space you have added to the LUNs used by your existing VMFS volume will not be available and you will not be able to reclaim the space without deleting and recreating the LUN. So as has been pointed out you may want to create new LUN with space wanted for datastore, format as VMFS and then svmotion your VMs to the new datastore.

You can then remove the old datastore, delete the old LUN and reclaim the space on your SAN.

[gmboy]

Using Equallogic, iSCSI and ESX 3.5 Update 4

1. Storage VMotion local storage

2. Remove Volume from ESX

3. Resize the volume

4. Rescan iSCSI

5. Add Storage to ESX

6. Storage VMotion