VMware Cloud Community
wd300
Contributor
Contributor
Jump to solution

Maximum virtual HDD size

Im wondering what the maximum size that I can create a second virtual hard disk on a vm. No matter how large I make the block size of the data store, the most it will allow is 256GB and I have a LUN that is 1TB

Reply
0 Kudos
1 Solution

Accepted Solutions
a_p_
Leadership
Leadership
Jump to solution

It's the block size of the datastore with the base folder of the VM which is important. The reason for this is that snapshots of virtual disks are created in this base folder by default. Therefore any virtual disk attached to a VM must not exceed the max. size allowed by the block size of the base datastore.

André

View solution in original post

Reply
0 Kudos
8 Replies
Troy_Clavell
Immortal
Immortal
Jump to solution

2TB minus 512bytes is largest, but you would need an 8MB block size on your LUN.  What size are you trying to present, and what is the block size of the LUN in question

Block SizeMaximum File Size
1 MB256 GB - 512 Bytes
2 MB512 GB - 512 Bytes
4 MB1024 GB - 512 Bytes
8 MB2048 GB - 512 Bytes
Reply
0 Kudos
wd300
Contributor
Contributor
Jump to solution

Yeah, that's what I thought but even when I use the 8MB block size I get the same max of 256GB. I should check with the SAN guy to see how they carved out the space. I was told the LUN size is 1.05TB and I want to use all of it for one device that will be the location of my Exchange 2010 database.

Reply
0 Kudos
Troy_Clavell
Immortal
Immortal
Jump to solution

can you post a screen shot of the properties of the datastore in question? Something like below?

Capture.PNG

a_p_
Leadership
Leadership
Jump to solution

It's the block size of the datastore with the base folder of the VM which is important. The reason for this is that snapshots of virtual disks are created in this base folder by default. Therefore any virtual disk attached to a VM must not exceed the max. size allowed by the block size of the base datastore.

André

Reply
0 Kudos
a_p_
Leadership
Leadership
Jump to solution

... about the max. size of a virtual HDD to support snapshots.

Take a look at "Calculating the overhead required by snapshot files" at http://kb.vmware.com/kb/1012384

André

Reply
0 Kudos
Troy_Clavell
Immortal
Immortal
Jump to solution

yes, and my assumption, which is, all VM files reside on the same LUN, which is how we provision our enviornment, may not be the case in your situation.  If that is so, as a.p.  pointed out, this is your issue.  You can confirm the guest is using different HDD's from different LUNS?

Reply
0 Kudos
wd300
Contributor
Contributor
Jump to solution

Troy where did you get that information in your screenshot. I was just thinking to myself about how I could check the block size on existing datastores and then saw your post.

Reply
0 Kudos
Troy_Clavell
Immortal
Immortal
Jump to solution

if you go to the summary tab of an ESX(i) Host, then right click on a Datastore--properties, that is where I got that particular screen shot.

Reply
0 Kudos