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Regarding DATASTORE Capacity on VMware ESXi, 4.1.0

Clement P
Clement P asked
on
Hi,

I've just installed three 2 TB SAS HDD's on our HP SAN as RAID 05 Virtual Disc. So the available disc space for usage is 4 TB.
I can see the new LUN on VMware ESXi, 4.1.0 on Configuration Tab, Datastores>Devices as LUN 4 with Capacity 3.64 TB ( Fig1).
However when I added this new LUN to existing Datastore  ( Name:300gb) on ESXi, the capacity of this LUN is 1.64 TB instead of 3.64 TB. What could be the problem here please ? And how can I get full 3.64 TB space for usage

Thanks,
Clement
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Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
the maximum size of a datastore for ESXi 4.1 is 2TB-512 bytes,

Configuration Maximums for VMware vSphere 4.1

You could

1. upgrade to ESXi 5.5 or ESXi 6.0, because ESXi 5.5 supports datastores up to 62TB.

Configuration Maximums for VMware vSphere 5.x



2. Re-create your LUNs, smaller than 2TB-512bytes, e.g.

2TB and 640MB datastore.
Luciano PatrãoICT Senior Infraestructure  Engineer  

Commented:
Hi,

Did not understand if you have a Datastore of 4TB, or just have a Virtual Disk(in HP SAN) of 4Tb size.

In ESXi 4.x LUNs are limited to 2Tb.

http://kb.vmware.com/kb/3371739

If this is the case, just create 2 LUNs of 2Tb and this will do the trick.

Jail

Author

Commented:
Thank you Andrew and Luciano.

Now the question is, how easy is it to remove the attached LUN from a Datastore of VMware ESXi.
In my case I've added the new LUN to an existing Datastore called 300gb ( For reference Fig2)

This Datastore initially was of only 1.09 TB  and I added the new LUN (1.64 TB) to the same Datastore.
How can I delete the one I added please  ?

Thanks,
Clement
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
You will need to reformat and re-install.

Author

Commented:
You mean the whole Datastore ?

Author

Commented:
This is the scenario ( Attached fig )

I need to delete -2 ( New ) LUN
Fig3.JPG
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
You need to ensure

1. the LUNs presented to ESXi 4.x are smaller than 2TB-512 bytes, and therefore the only way to accomodate this, is to alter the RAID/LUN at the storage controller, outside of ESXi 4.1.

So where is ESXi installed on a SD card or USB flash drive?

You will need to re-do your RAID, and that may mean a re-format, re-LUN, re-RAID, and re-install.

The datastore labelled 300GB, is this a single disk of 2.7TB, if so, you will not be able to use it all under ESXi 4.1 VMFS3, max is 2TB.

I've just noticed, you are using extents.....

so you have 3 x 2TB SAS disks locally connected to this server ?

I would NOT recommend using extents as a method of increasing datastore sizes.

Again Max Datastore is 2TB-512bytes.

Author

Commented:
So you are suggesting me to go to  the HP Storage Management Utility directly where I created the LUN and delete the LUN or reformat it.
Which means I'm not doing anything on VMware ESXi ?
I hope you understood my scenario ?

I have a Datastore on ESXi called 300gb and this was of capacity 1.09 TB.Since the VM using this Datastore were running low on disc space,i added a new LUN of 1.64 TB to the same Datastore 300gb.
If you look the picture I attached Fig3,you would be able to understand it.
Now I want to remove this newly added LUN of 1.64Tb without effecting the VM's using the Datastore 300gb and what is the best method please ?

Thanks,
Clement
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
Correct, you will need to remove, re-create LUNs on the Storage Management Utility, and then Add New Storage on ESXi.

If you remove the newly added extent of 1.64TB, there is a risk of causing datastore corruption.

You cannot add and remove Extents, plug and play. Once added the datastore is updated.

I would create a new LUN or less than 2TB, and then move the VMs.

Author

Commented:
Thank you Andrew,
I learned one more fact that " It is not possible to remove an extent from an existing datastore. Once an extent is added, it is not possible to remove it " from the VMware Knowledge Base article " Cannot remove a LUN extent (1003344) ".
In simple words, the article is suggesting me to move all VMs off the datastore temporarily, destroy  and re-create it as a new datastore, then move the VMs back.

But alternatively you are suggesting me to delete the New LUN or (Extent in VMware terms) itself from the SAN. But I hope this wont corrupt the Datastore itself ? Because we've our file server using that Datastore.

Thanks,
Clement

Author

Commented:
To confirm as you are aware my Datastore namely 300gb is having 2 extents. One - Old LUN of 1.09 TB and other - New LUN of 1.64 TB.
So you are suggesting me to delete the second extent or the New LUN of 1.64 TB from the SAN itself while having the Datastore with other extent i.e. with Old LUN of 1.09 TB in operational condition ?
Andrew Hancock (VMware vExpert / EE Fellow)VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017

Commented:
As I posted, you cannot remove the extent you have added, this is not plug and play.

or course, you will need to ensure you move or backup on the datastore, before you remove the LUNs, or you will lose your data!

if you have the space, you can create a new LUN, move the VMs, and then once the VMs have been moved removed the datastores.

When creating new datastores create them no larger than 2TB, and do not use extents.
VMware and Virtualization Consultant
Fellow 2018
Expert of the Year 2017
Commented:
BACKUP ALL THE VMS, or move THEM, and then DESTROY BOTH

Old LUN of 1.09 TB and other - New LUN of 1.64 TB.

Create a new LUN of 2TB-512 bytes. (if you really need such a large LUN).