Max vmdk file size

[Cievo]

Hello

One of our customer running on VMWare created biggest file that he could on datastore formated by 1MB block size. It was 256GB file.

Now when customer tries to create snapshot of that virtual machine he receives error:

Jan 27 13:23:49.081: vmx| FILE: File_VMFSSupportsFileSize: Requested file size (274911461376) larger than maximum supported filesystem file size

(274877906944)

Jan 27 13:23:49.081: vmx| DISKLIB-LIB : CREATE CHILD:

"/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody_1-000001.vmdk"

-- vmfsSparse cowGran=0

Jan 27 13:23:49.083: vmx| FILE: File_VMFSSupportsFileSize: Requested file size (277025916928) larger than maximum supported filesystem file size

(274877906944)

Jan 27 13:23:49.083: vmx| DiskLibCreateCustom: if your disk is on VMFS, you may consider increasing the block size.

Jan 27 13:23:49.084: vmx| DISKLIB-LIB : Failed to create link: The

destination file system does not support large files (12) Jan 27

13:23:49.084: vmx| SNAPSHOT: BranchDisk: Failed to create child disk '/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody_1-000001.vmdk'

: The destination file system does not support large files (12) Jan 27

13:23:49.084: vmx| DISKLIB-VMFS :

"/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody_1-flat.vmdk"

: closed.

Jan 27 13:23:49.084: vmx| SNAPSHOT: SnapshotBranch: Unlinking '/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody-000001.vmdk'.

Jan 27 13:23:49.085: vmx| DISKLIB-VMFS :

"/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody-000001-delta.vmdk"

: open successful (17) size = 10737418240, hd = 0. Type 8 Jan 27

13:23:49.086: vmx| DISKLIB-VMFS :

"/vmfs/volumes/4b586f50-2a50b44a-e993-00145e7b4ffd/scustody/scustody-000001-delta.vmdk"

: closed.

Jan 27 13:23:49.242: vmx| SNAPSHOT: SnapshotBranch failed: The destination file system does not support large files (5).

Jan 27 13:23:49.244: vmx| CPT current = 2, requesting 6 Jan 27

13:23:49.244: vmx| Checkpoint_Unstun: vm stopped for 547029 us Jan 27

13:23:49.245: vmx| SnapshotVMX done with snapshot 'test': 0 Jan 27

13:23:49.245: vmx| Msg_Reset:

Jan 27 13:23:49.245: vmx| http://msg.checkpoint.save.fail2.std3 Error encountered while saving snapshot.

Jan 27 13:23:49.245: vmx| The destination file system does not support large files.----

---

Jan 27 13:23:49.246: vmx| Vix: :

VMAutomationCreateSnapshotCallback: Got CreateSnapshot callback, snapshotErr = 12, UID = 0

We know how to fix it - create new datastore with 2MB (or more) blocks and move that disk there. That's fine. But why did VMWare let customer to create such a huge file when it cannot work with it anymore? Shouldn't there be some kind of user-error protection?

Thank you for answer,

Ondrej Zilinec - Cievo

...Good question is half of the answer...

[RParker]

Well for one the 1MB block size is limited for a SINGLE file, not ALL files pertaining to a VM. So if a SINGLE file is larger than 256GB in size, you will be OVER the limitation. A snapshot is a history of ALL the changes in that VMDK, and if you change EVERY bit then the snapshot cannot be larger than the original VMDK, but you would end up with 2 256GB files.

So they didn't allow creation of a single large file, but if you use thin provisioning, there may not be enough space left.

[Cievo]

VMDK file was created as max size for particular datastore formated in 1MB.

I don't think that's correct what you wrote. Snapshot doesn't represent bit changes to VMDK. Snapshot represents transaction logs made to VMDK file. And when you delete snapshot you re-play all transaction logs recorded in snapshot file to original VMDK file.

You can see snapshot file couple times bigger than original VMDK file.

Ondrej Zilinec - Cievo

...Good question is half of the answer...

[continuum]

You can see snapshot file couple times bigger than original VMDK file.

Yes - you could have a thin provisioned vmdk with nominal size of 256 Gb but real size of 50 Gb. Then the snapshot can grow upto the nominal size of 256 GB but never larger.

Snapshot doesn't represent bit changes to VMDK

Your assumption is wrong. Snapshots capture changes to the original vmdk bit by bit - or block by block

___________________________________

VMX-parameters- Workstation FAQ -[ MOA-liveCD|http://sanbarrow.com/moa241.html] - VM-Sickbay

[Cievo]

OK, when you create 100GB thick VMDK file. It creates 100GB on VMFS Datastore. When I create snap-shot from this disk, VMWare creates new file (snap-shot file) on VMFS Datastore. Is that correct?

And if this is correct, new snapshot file created on VMFS Datastore can also have max size of 256GB (with 1MB block formating).

But if all these things are correct, I don't understand why I cannot create snapshot of 256GB VMDK file if snap-shot is different file on VMFS Datastore.

Ondrej Zilinec - Cievo

...Good question is half of the answer...

[JroscoPHD]

I have tested and seen that a snapshot file can grow bigger than the orignal disk. Then it would be bigger than the Block limit. Thay might be the reason they deny it.

James Rosikiewicz

www.PHDVirtual.com makers of esXpress

[Cievo]

If you assume this, than it would be logical to restrict to create snapshot even for smaller disk than 256GB. If snapshot can be bigger than original disk, it can happend that 250GB disk can have bigger snapshot also.

Ondrej Zilinec - Cievo

...Good question is half of the answer...

[JroscoPHD]

Good point. I never tried to put a Snap on a 200G VMDK on a 1M Block Disk. Need to try that.

Then try a 210G disk and see if VMware lets you create it.

www.PHDVirtual.com makers of esXpress

[Legacy User]

Hi Ondrej,

I hava the same problem that you had, disk with 256 GB in a 1 MB block size datastore (http://communities.vmware.com/thread/255515).

Can you please tell me if it is safe to the migration through SVmotion (online) or, in this case, it should be done offline?

Thanks

joaquim

[Cievo]

I wouldn't risk online storage vMotion. I looks to me, that guys in VMWare made more bugs in vShere than fixed.

Ondrej Zilinec - Cievo

...Good question is half of the answer...

[thejourney]

I ran into this issue today, I had a VM (exchange 2010), split on different luns (os, Logs, and Data) OS lun was

formatted 1 MB, Logs Lun 1 MB, Data lun 8 MB. VMX files were with the first VMDK

I created on a 1 MB formatted LUN. All snaps were failing with the “not enough

Space for .VMX file” ???

Fixed by moving config files to 8MB formatted LUN. Now snaps are working. :smileylaugh:

I use online storage migration all the time. Works great, big thanks to

those guys at VMWare..

I wouldn't risk online storage vMotion. I looks to me, that guys in VMWare made more bugs in vShere than fixed.

Ondrej Zilinec - Cievo

...Good question is half of the answer...