Storing Thin VMDK on NFS

[seniord]

I would like to store 'thin' vmdk files on an NFS datastore (not a dedicated NAS device) running Windows or Linux/Unix.

When using Windows 2003 Standard Server running Windows Service for Unix, I cannot create or copy thin disks to the Windows NFS share. Can anyone confirm whether storing thin vmdk files is supported on a Windows NFS share?

Are there any versions/flavours of Unix or Linux running NFS services that support storing thin vmdk files?

Any guidance would be appreciated.

[Texiwill]

Hello,

All Linux filesystems will store thin disks as they are considered to be UNIX Sparse Files. WHere just the used inodes are allocated.

Best regards,
Edward L. Haletky
VMware Communities User Moderator, VMware vExpert 2009, DABCC Analyst
====
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[kjb007]

By create, do you mean you used vmkfstools -d thin when you were creating a disk and it was unsuccessful?

-KjB

VMware vExpert

[seniord]

When creating a thin vmdk file on the NFS volume, the size on disk is 10G (see below). When creating a thin vmdk on a VMFS volume, the size on disk is 1.0M (see below). DC1:VMTemplates is the Windows NFS volume, VDisk1V1 is the VMFS volume.

# vmkfstools -c 10G -d thin /vmfs/volumes/DC1\:VMTemplates/TEST.vmdk

# cd DC1\:VMTemplates/

# ls -lhs

total 12G

10G -rw------- 1 root root 10G May 7 2009 TEST-flat.vmdk

512 -rw------- 1 root root 397 May 7 2009 TEST.vmdk

# vmkfstools -c 10G -d thin /vmfs/volumes/VDisk1V1/TEST.vmdk

# cd ..

# cd VDisk1V1/

# ls -lhs

total 1.7M

1.0M -rw------- 1 root root 10G May 7 15:20 TEST-flat.vmdk

64K -rw------- 1 root root 397 May 7 15:20 TEST.vmdk

[seniord]

In addition, when cloning a thick vmdk on VMFS to a thin vmdk on NFS, the cloned vmdk file is stored in thick format (see below). DC1:VMTemplates is the Windows NFS volume.

# ls -lhs

total 25G

25G -rw------- 1 root root 24G Apr 1 08:39 WIN24GB-X32STD-flat.vmdk

64K -rw------- 1 root root 372 May 6 11:55 WIN24GB-X32STD.vmdk

# vmkfstools -i WIN24GB-X32STD.vmdk -d thin /vmfs/volumes/DC1\:VMTemplates/WIN24GB-X32STD-THIN.vmdk

Destination disk format: VMFS thin-provisioned

Cloning disk 'WIN24GB-X32STD.vmdk'...

Clone: 100% done.

# cd /vmfs/volumes/DC1\:VMTemplates/

# ls -lhs

total 26G

25G -rw------- 1 root root 24G May 8 2009 WIN24GB-X32STD-THIN-flat.vmdk

512 -rw------- 1 root root 438 May 8 2009 WIN24GB-X32STD-THIN.vmdk

#

[kjb007]

Have you verified this is the same as is seen on the storage side as well?

-KjB

VMware vExpert

[Texiwill]

Hello,

'Thin' disks are actually hard to determine are in use. Must storage allocation detection tools, like 'df' will NOT show the VMDKs real size only that 10GB has been allocated. That is really an issue in how the file system responds more than anything else. It does not want you to suddenly run out of space when you allocate the other inodes for something it has already allocated.

VMFS does not have this problem. So you really need is a tool that detects sparse files and reports accordingly.

Best regards,
Edward L. Haletky
VMware Communities User Moderator, VMware vExpert 2009, DABCC Analyst
====
Now Available on Rough-Cuts: 'VMware vSphere(TM) and Virtual Infrastructure Security: Securing ESX and the Virtual Environment'
Also available 'VMWare ESX Server in the Enterprise'
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[seniord]

KjB - How would I check this and what would I be looking for? I was just monitoring the network traffic.

[kjb007]

On your storage server, how big are the created disks? The output your showed earlier was from ESX, correct? What is the corresponding size from the storage side? That's what I meant earlier.

-KjB

VMware vExpert

[seniord]

Hi,

This issue was identified as a problem with the native Windows NFS Services for Unix. I was using the default Windows NFS Services available with Windows 2003 Server R2 SP2 to setup and configure my NFS share.

After following the VMware KB; , and installing the downloadable Windows Services for Unix, this resolved the issue. A collegue was able to reproduce the same issue using the native services as well.

Thanks for any responses.