06blade
Enthusiast
Enthusiast

Storage Views - uncommitted space and shared space

Please could someone explain what uncommitted space and shared space actually are in the storage views for a virtual machine.

I thought uncomitted space was something to do with thin provisioning but my VM's which show uncommitted space of around 4GB don't use thin provisioning and are not in snapshot.

As for shared space, no idea what this column refers to. Thankfully no vm's are showing shared space.

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10 Replies
ab_lal
Enthusiast
Enthusiast

In Thin Provisioning Environment, Uncommitted Space is the balance between Provisioned Space and Space Used

Eq: If you have provisioned 20 GB VM with thin provisioning and currently it is using 12 GB then the balance 8 GB is the Uncommitted Space

Shared Space would only be visible when a Replicated LUN is attached to 2 VM's as a SRDF disk however only one connection from the VM to the LUN will be active.

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06blade
Enthusiast
Enthusiast

Thanks for that, but in my case the Storage Views is showing 4GB uncommitted space on a large number of virtual machines.

These virtual machines are not using Thin Provisioned disks.

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a_p_
Leadership
Leadership

The uncommitted space you see for VM's with thick provisioned disks is most likely the amount of the memory that you assigned to the VM (disk space for the vmem file).

Shared space is the disk space shared between e.g. linked clones, i.e. the base disk.

André

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06blade
Enthusiast
Enthusiast

Getting more worried by the day now.

Got a VM with a 40GB vmdk, and 4GB RAM. So it's effectively 44GB in size.  The vmdk is thick provisioned.  The VM is in snapshot at the moment, currently 9.38GB in size.  I can confirm all this information is correct when browsing the datastore and checking the contents.

Storage views is reporting the following :-

Space Used, 53.39 GB (vmdk + vmem + snapshot)
Snapshot Space, 9.38 GB
Provisioned Space, 88.01 GB
Uncommitted Space, 34.62 GB

The datastore is 500GB in size, of which 282.55 GB is currently free.

So provisioned space of 88.01 GB seems to come from space used + uncommitted. But what is uncommitted space of 34.62 GB ?

I'm worried that we are about to go down in a big way.

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DSTAVERT
Immortal
Immortal

I would be most concerned about a 9GB snapshot that in your first post didn't exist.

-- David -- VMware Communities Moderator
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a_p_
Leadership
Leadership

From how it looks like you took the snapshot while the VM was powered off.

So let's go through the values  and how I understand them:

  • Space used: virtual disk (40GB) + swap space (4GB) + snapshot space (9.38GB ) + some small files -> ~53.38GB
  • Snapshot Space: ~9.38GB (that's easy)
  • Provisioned Space: 2 x virtual disk (80GB) + 2 x swap space (8GB) -> ~88.01GB
  • Uncommitted Space: prov. space for snapshot disk (40GB) - already in use (9.38GB) + swap space for snapshot (4GB) -> ~34.62GB

André

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06blade
Enthusiast
Enthusiast

That's been created today to test some upgrades.

We also have a few backups running which put vm's into snapshot, but most of the time things aren't in snapshot.

the uncomitted space is a concern.

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06blade
Enthusiast
Enthusiast

Hi André

just looking at the tasks and events. The snapshot was created after the vm was powered. It has 1 x 40GB hard drive.

browsing the datastore I'm seeing the following

srv1-vmdk     41,943,040.00 kb

srv1-000002     5,866,496,00 kb

srv1-Snapshot1.vmsn     4,203,862.00 kb

srv1-1bf3ebba.vswp     4,194,304.00 kb

plus the log files etc.

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a_p_
Leadership
Leadership

Yes, I understand that you only have one virtual disk. However, as soon as you take a snapshot in VMware, the current virtual disk file will be treated as read-only and a new virtual disk file - to which all subsequent changes will be written - is being created. This file can grow up to the size of the base disk. That's why the provisioned space contains 2 x 40GB for the virtual disk.

André

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06blade
Enthusiast
Enthusiast

Thanks Andre, appreciate all your help with this.

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