Enabling CAW on a datastore using the ESXi CLI

If you did not have support for Compare and Write (CAW) in Data ONTAP operating in 7-Mode, you must manually enable CAW support when you transition to clustered Data ONTAP. Clustered Data ONTAP supports CAW by default.

Before you begin

About this task

CAW must be enabled only when no I/O or VMs are actively running on the VMFS datastore.


  1. Open the Inventory Assessment Workbook generated by the Inventory Collect Tool (ICT).
  2. Navigate to the SAN Host Filesystems tab.
  3. Verify the CAW status for the datastore.
    The ATS/CAW value for the datastore should display Disabled, and the Filesystem column should display VMFS.x.
  4. Note the name of the datastore in the Disk column
  5. Log in to the ESXi console using SSH.
  6. List the device and partition details: ~ # vmkfstools -Ph -v1 datastore_path
    datastore_path is the datastore name from the Disk column of the Inventory Assessment Workbook.
    # vmkfstools -Ph -v1 /vmfs/volumes/datastorename
    VMFS-5.60 file system spanning 1 partitions.
    File system label (if any): datastorename
    Mode: public
    Capacity 9.8 GB, 8.2 GB available, file block size 1 MB, max file size 64
    Volume Creation Time: Mon Dec 9 10:29:18 2013
    Files (max/free): 27408/27394
    Ptr Blocks (max/free): 64512/64495
    Sub Blocks (max/free): 3968/3964
    Secondary Ptr Blocks (max/free): 256/256
    File Blocks (overcommit/used/overcommit %): 0/1593/0
    Ptr Blocks (overcommit/used/overcommit %): 0/17/0
    Sub Blocks (overcommit/used/overcommit %): 0/4/0
    Volume Metadata size: 590675968
    UUID: 52a59b7e-52d2fb6c-11d6-001ec9d631cb
    Partitions spanned (on "lvm"):
    Is Native Snapshot Capable: YES
  7. Note the first device name and partition number.
    In the preceding example, naa.600a098044314c6c442b446d51376749:1 is the device name and partition number.
  8. Use the device ID and partition number to enable CAW on the datastore: ~# vmkfstools --configATSOnly 1 /vmfs/devices/disks/device-ID:Partition
  9. Verify that the VMFS volume has been configured with ATS only: # vmkfstools -Ph -v1 /vmfs/volumes/VMFS-volume-name
    VMFS-5.54 file system spanning 1 partitions.
    File system label (if any): ats-test-1
    Mode: public ATS-only