VMware VM Backup & Leftover Files

[Sprechen_Sie_SE]

I am performing a full backup of four different vms using BE 2010.  We are on ESX 4.1.  The backups are going to a backup to disk folder on a QNAP NAS.  Two of the machines have leftover vmdk and -ctk files after each backup is complete.  I assume BE is making a snapshot of the vm while backing up and then not removing the files after the backup is complete.  This is in turn using up datastore space on our server.  The other two machines do not exhibit this behavior.  Does anyone know what might cause these leftover files and how it can be fixed?

TIA,
Kurt

[RahulG]

refer the following infromation from the doc http://www.symantec.com/business/support/index?page=content&id=HOWTO54202 

scsix:x.ctkenabled = "true | false"

Virtual machines running on ESX 4.0 or later hosts (with virtual hardware 7) can keep track of disk sectors that have changed. This feature is called Changed Block Tracking (CBT).

On a virtual machine, the virtual disk block changes are tracked from outside of the virtual machine in the virtualization layer. When a backup is performed, only the blocks changed since the last backup are transmitted.

 True = ctk enabled for this specific disk

 False = ctk disabled for this specific disk

-For each virtual disk and snapshot disk there is a .ctk file. For example:

vmname.vmdk
vmname-flat.vmdk
vmname-ctk.vmdk
vmname-000001.vmdk
vmname-000001-delta.vmdk
vmname-000001-ctk.vmdk

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ctkEnabled = "TRUE | FALSE"

 This paramater enables or disables the Changed Block Tracking (CBT) at the virtual machine level.  the parameter must be specified for every scsi disk also.

See Vmware technote "http://kb.vmware.com/selfservice/microsites/search.do?cmd=displayKC&externalId=1031873" for more information.

[pkh]

Care to explain how enabling/disabling Change Block Tracking would solve the user's problem of snaphots being left behind.

[Lesta_G]

I take it your seeing snapshots left in the snapshot manager  in vCenter client? with SYMANTEC DD-MM-YY as the snapshot name?

How often is this happening to the VMs , every backup?

are you removing the snaphosts via snapshot manager?