To deduplicate a file system

1. Create the file system fsvol1:

   # mkfs -t vxfs -o /dev/vx/rdsk/fsdg/fsvol1

2. Mount the file system as /mnt1:

   # mount -t vxfs /dev/vx/dsk/fsdg/fsvol1 /mnt1

3. Make a temporary directory, temp1, on /mnt1 and copy the file1 file into the directory:

   # mkdir /mnt1/temp1
   # cd /mnt1/temp1
   # cp /root/file1 .
   # /opt/VRTS/bin/fsadm -S shared /mnt1
   Mountpoint  Size(KB) Available(KB) Used(KB) Logical_Size(KB) Shared
   /mnt1       4194304  3849468       283852   283852           0%

   The file1 file is approximately 250 MB, as shown by the output of the fsadm command.

4. Make another temporary directory, temp2, and copy the same file, file1, into the new directory:

   # mkdir /mnt1/temp2
   # cd /mnt1/temp2
   # cp /root/file1 .
   # /opt/VRTS/bin/fsadm -S shared /mnt1
   Mountpoint  Size(KB) Available(KB) Used(KB) Logical_Size(KB) Shared
   /mnt1       4194304  3588700       548740   548740           0%

   By copying the same file into temp2, you now have duplicate data. The output of the fsadm command show that you are now using twice the amount of space.

5. Enable deduplication on the mount point /mnt1:

   # /opt/VRTS/bin/fsdedupadm enable -c 4096 /mnt1
   # /opt/VRTS/bin/fsdedupadm list /mnt1
   Chunksize Enabled Schedule NodeList           Priority     Filesystem
   ---------------------------------------------------------------------
   4096      YES     NONE     node1.company1.com low          /mnt1

6. Start a deduplication run on the mount point /mnt1:

   # /opt/VRTS/bin/fsdedupadm start /mnt1
   UX:vxfs fsdedupadm: INFO: V-3-20: 0000: deduplication is started
   on /mnt1.

7. Check status of deduplication:

   # /opt/VRTS/bin/fsdedupadm status /mnt1
   Saving Status    Node               Type                   Filesystem
   ---------------------------------------------------------------------
   74%    COMPLETED node1.company1.com MANUAL                 /mnt1
   2011/07/04 10:56:05 End detecting duplicates and filesystem changes.
   Status 0

8. Verify that the file system was deduplicated by checking how much space you are using:

   # /opt/VRTS/bin/fsadm -S shared /mnt1
   Mountpoint  Size(KB) Available(KB) Used(KB) Logical_Size(KB) Shared
   /mnt1       4194304  3834364       299136   566176           47%

   The output shows that the used space is nearly identical to when you had only one copy of the file1 file on the file system.