Shrinking thin VM hard

[Reza Fathi]

Hi

I have a VM on esxi 6 server and I wanted to shrink its vmdk hard. I did these steps:

1- used sdelete -z c:

2- powered off the vm

3- ssh to esxi host and used vmfsktools -K DC2.vmdk

4- powered on the VM

After those steps, esxi showed 52GB hard usage and that was fine. (before was 110 GB) but when I used ls -lh on esxi , it shows DC2-flat.vmdk file with 400GB size. Is this size real? if not , is that occupying that size?

[a_p_]

What you see in that column is the provisioned size. To see the real disk space usage run e.g. ls -lisa, which will show you the used disk space in the second column.

André

[Reza Fathi]

Thanks. That 400gb is not occupied the storage by vm right?

What is the best practice to use sdelete to shrink vm hard? Is that safe to use on windows installed drive?

[a_p_]

Correct, the 400GB is the provisioned disk size, i.e. the size that's configured in the VMs settings, and the maximum that the .vmdk file can grow to.

sdelete is usually save to use, because it writes to a file until the disk fills up, and then deletes that file.

André

[Reza Fathi]

I have many vms on esxi 8. Is this method works on esxi 8 too?

[a_p_]

This should work regardless of the ESXi version.

Just make sure that the VM does not have active snapshots !!!

André

[Reza Fathi]

I have a vm hard added as .mvmdk so can i use sdelete and then vmkfstool -K on this too?

[Casey]

Have you tried to do a storage migration and selecting each disk and changing it to Thin Provisioned? 

[Casey]

The DC2-flat.vmdk file you see listed with a size of 400GB is the actual size of the virtual disk as it is allocated on the datastore. This does not necessarily mean it is using that entire space for data, especially if you have performed steps to zero out and shrink the disk.

Here's a breakdown of what's happening:

1. SDelete: Running sdelete -z inside the guest OS zeros out free space, making it possible to reclaim unused space at the VMFS level.
2. VMKFSTools: The command vmkfstools -K DC2.vmdk is used to punch out zeroed blocks and reclaim space on a thin-provisioned virtual disk.

After performing these steps, the space within the VM should be reclaimed, and the size shown in vSphere (52GB) reflects the used space within the VM. However, the ls -lh command shows the allocated size on the datastore.

Thin-Provisioned Disks

If your VMDK is thin-provisioned:

• The actual used space on the datastore should be less than the allocated size. This discrepancy is normal and indicates that the space within the disk is not entirely occupied by data.

Verifying Actual Usage

To verify the actual space usage, you can use the following command:

du -h /vmfs/volumes/your_datastore/your_vm_directory/DC2-flat.vmdk

This command will show you the actual disk usage, which should reflect the reclaimed space.

Thin-Provisioning Check

Ensure your disk is thin-provisioned by using the following command:

vmkfstools -D /vmfs/volumes/your_datastore/your_vm_directory/DC2.vmdk

Look for a line indicating if the disk is thin-provisioned.

Shrink Command

Ensure that the vmkfstools -K command was successful. You can also use vmkfstools -p to see the current allocation of blocks.

Conclusion

The size shown by ls -lh (400GB) is the provisioned size, not the actual used space. To ensure this space is not occupied, verify with du and confirm the thin-provisioned status with vmkfstools.

If this is still the case, try doing a storage migration to another DS and selecting each disk and changing it to "Thin Provisioning". 

I am very interested to see how this goes. Please follow up. 

[a_p_]

>>> I have a vm hard added as .mvmdk ..

Is this ".mvmdk" just a typo? Please share details.

André

[Reza Fathi]

no that is not a typo.

[a_p_]

To me, this looks like someone renamed the virtual disks manually (e.g. using the vmkfstools -E .... command), and accidentally entered ".mvmdk" instead of ".vmdk".

André