How to create/ increase VMDK file size larger than 250GB

Hi Experts,

I have vmware esxi4.1 installed. Datastore is VMFS 3.4 with block size 1MB. I understand from this link that I can't create VMDK file larger than 250GB.

Is there anyway to create VMDK file larger than 250GB if VMFS3 block size is 1MB?

Could you let me know if there is any work around to increase VMDK file larger than 250GB?

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

yes, I have made 2, 3 or 4 VMDK files then from MS, Disk management combine into one big drive.

Another option if on a SAN is Raw device mapping to get around the 254GB limit
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
you need to increase the block size of the datastore, which means backup the VMs, change the datastore block size by re-formatting, and restore the VMs.

• 1MB block size – 256GB maximum file size
• 2MB block size – 512GB maximum file size
• 4MB block size – 1024GB maximum file size
• 8MB block size – 2048GB maximum file size


1. ESXi 5.0
2. You could create a new vritual disk on the datastore, and expand/strip in the OS. So you VM would have two virtual disks, striped and expanded in the OS.
3. Present a iSCSI LUN to the VM using Microsoft iSCSI Initiator.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
The ONLY way to do what you need is to change the block size as @hanccocka mentions. And, the only way to change the block size is to delete/remove the datastore and re-add it, using the appropriate block size. You obviously need to backup all data off your datastore first because a reformat happens when re-adding the datastore.

Determine the Perfect Price for Your IT Services

Do you wonder if your IT business is truly profitable or if you should raise your prices? Learn how to calculate your overhead burden with our free interactive tool and use it to determine the right price for your IT services. Download your free eBook now!

bominthuAuthor Commented:

Thanks all for your quick responds. I know the only way is to delete and recreate Datastore. I'm just trying to know if there is work around because I heard that there is work around without deleting Datastore.

If I can't get to know what is workaround, I think the only easy way I can see for me now is to stripe the volumes. I have don't that before long time ago in physical machine but I can't remember I did for system drive volume (C: and D:) or I did for non system volume (D: and E:) .
I mean C: is my operating system volume.

Could you let me know if I can stripe all volumes including system drive (C: D: E:) to become one big dynamic volume in VM? I just worry of anything will happen to system volume

The closest I believe are these articles:

That is for a local volume (i.e. same disks that have both ESX/i installed and the VMFS). Except for moving data, removing/re-adding is for the most part your best bet. And, personally, I would even copy/backup my data even before trying to use vmkfstools

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
I would not recommend striping a system C: volume. Just stripe a data volume.
bominthuAuthor Commented:

Anyway can we include C: drive volume together with the rest volume in striping?
It is just risky ?

If it is that we can stripe and just risky, I'll test in another VM first.
Could you let me know if you have done or tested striping C: volume ?
In my case, I need to extend C: volume especially that's why

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
spanning not supported on system, boot drive C:, spanning options not available.

so your options to extend your C: drive would be to increase the virtual disk size requiring blocksize change.

what requirement do you have, could you use Mount in the following empty NTFS folder, if its a filer server? on the c: drive?

A Windows Junction or Unix Style mount point.
bominthuAuthor Commented:
Hi hanccocka

I have MSA2012 storage created multiple LUNs.
How can I connect to specific LUNs using Microsoft iSCSI connector ?

Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Enabled Microsoft iSCSI initiator, and assign the iSCSI IQN to the LUN on the SAN.
bominthuAuthor Commented:
Hi Hanccocka,

My server is exchanger server, recently database size and logs file size is growing too much.
I think I got an idea. I'll just attach one more VMDK file to the VM and create new database in that VMDK and migrate some mailboxes to it,

Thanks a lot for your help
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Personally I would split the datastores across, mutlple LUNs and Disks.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
and the database on single virtual disks, and logs on another disks, on different datastores or LUNs
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.