Home > netapp > Splitting off a NetApp FlexClone Volume to Create an Independent Volume

Splitting off a NetApp FlexClone Volume to Create an Independent Volume

FlexClone volumes can be used indefinitely, but there are a number of good reasons for a storage administrator to split off a FlexClone volume to create a fully independent FlexVol volume. They may wish to replace the current parent FlexVol volume with the modified FlexClone volume, need to free the blocks pinned down by the FlexClone volume base
Snapshot copy, or wish to have Data ONTAP enforce space reservations for the volume for more predictable administration. Performance is not one of the reasons. Since the clone volume uses the same aggregate as the parent, they both get to use the exact same disks. Both take advantage of WAFL and NVRAM for fast writes, and since changes can be written to anywhere on disk, it doesn’t matter if it is the clone or independent metadata that gets updated. Here is how it’s done…
First customer  needs to make sure there is enough space available in the aggregate to support the new independent volume:
toaster> df -g GadgetTools
Filesystem total used avail capacity Mounted on
/vol/GadgetTools/ 20GB 5GB 14GB 30% /vol/GadgetTools/
/vol/GadgetTools/.snapshot 20GB 3GB 16GB 19%
/vol/GadgetTools/.snapshot
toaster> df -Ag aggr1

Aggregate total used avail capacity
aggr1 109GB 44GB 65GB 41%
aggr1/.snapshot 5GB 0GB 5GB 0%
The GadgetTools volume and its associated Snapshot copy area take up 40GB. There is still 65GB available in the containing aggregate, so the coast is clear. Customer  initiates the split and checks progress a little bit into the split:
toaster> vol clone split start GadgetTools
Thu Sep 23 18:19:19 GMT [wafl.scan.start:info]: Starting volume clone split on volume GadgetTools.
Clone volume ‘GadgetTools’ will be split from its parent.
Monitor system log or use ‘vol clone split status’ for progress.
toaster> vol clone split status
Volume ‘GadgetTools’, 1263616 of 1440768 inodes processed (88%)
4676608 blocks scanned. 2401280 blocks updated.
Thu Sep 23 18:19:30 GMT [wafl.vol.add.spcGuar:info]: Space for volume GadgetTools is guaranteed.
Thu Sep 23 18:19:31 GMT [wafl.scan.clone.split.complete:info]: Volume GadgetTools, clone split complete.
After the split completes successfully, the space reservations are again enabled, and the space is guaranteed. Customer takes a closer look. Notice that the new volume has used approximately 40GB from the aggregate, and that the Snapshot copy area is currently empty. That’s because all the data is now associated with the volume, and there is no Snapshot copy data in the brand-new volume. In addition, the vol status command does not mention the volume being a clone or having space guarantees disabled. In fact, the vol options command shows that space is guaranteed for the volume.
toaster> df -g GadgetTools
Filesystem total used avail capacity Mounted on
/vol/GadgetTools/ 20GB 6GB 13GB 31% /vol/GadgetTools/
/vol/GadgetTools/.snapshot 20GB 0GB 20GB 0% /vol/GadgetTools/.snapshot
toaster> df -Ag aggr1

Aggregate total used avail capacity
aggr1 109GB 81GB 27GB 75%
aggr1/.snapshot 5GB 0GB 5GB 0%
toaster> vol status GadgetTools
Volume State Status Options
GadgetTools online raid_dp, flex create_ucode=on,
convert_ucode=on
Containing aggregate: ‘aggr1’
toaster> vol options GadgetTools
nosnap=off, nosnapdir=off, minra=off, no_atime_update=off, nvfail=off,
snapmirrored=off, create_ucode=on, convert_ucode=on, maxdirsize=1310,
fs_size_fixed=off, guarantee=volume, svo_enable=off, svo_checksum=off,
svo_allow_rman=off, svo_reject_errors=off, fractional_reserve=100
The clone split operation may take some time and proceeds in the background.  Customer uses the vol clone split status command to view the command’s progress. Both the clone and parent flexible volumes remain available during this process of splitting them apart. Upon completion, the Snapshot copy on which the clone was based will be unlocked in the parent FlexVol volume. Any Snapshot copies in the clone are automatically removed by Data ONTAP at the end of processing. The backing Snapshot copy in the parent FlexVol volume is not removed, since it may be needed by other FlexClone volumes or just desired as a regular Snapshot copy. Customer could have used the vol clone split stop command to stop the split process. If she did, all of the blocks that have already been duplicated by the vol clone split start command would remain split apart. If the split were ever started again, the remaining shared and new blocks would be separated. It’s not exactly like starting where the previous split left off, but it is close. Now that GadgetTools is an independent volume, Alice wants to tidy things up a bit. The backing Snapshot copy in the parent FlexVol volume is no longer needed. Plus now that most of the development work has stabilized, customer doesn’t need the volume to be quite as large or to reserve as large a fraction of space for the Snapshot copies. Lastly, the GadgetData clone isn’t needed because original data can be reused without modification. Here’s what she does:
toaster> snap list WidgetTools
Volume WidgetTools working…
%/used %/total date name
———- ———- ———— ——–
1% ( 1%) 0% ( 0%) Sep 23 20:00 hourly.0
1% ( 1%) 0% ( 0%) Sep 23 00:00 nightly.0
2% ( 1%) 1% ( 0%) Sep 22 22:21 clone_GadgetTools.1
toaster> snap delete WidgetTools clone_GadgetTools.1
toaster> snap reserve GadgetTools 20
toaster> df -g GadgetTools
Filesystem total used avail capacity Mounted on
/vol/GadgetTools/ 32GB 6GB 25GB 19% /vol/GadgetTools/
/vol/GadgetTools/.snapshot 8GB 0GB 7GB 0% /vol/GadgetTools/.snapshot
toaster> vol size GadgetTools 20g
vol size: Flexible volume ‘GadgetTools’ size set to 20g
toaster> df -g GadgetTools
Filesystem total used avail capacity Mounted on
/vol/GadgetTools/ 16GB 6GB 9GB 39% /vol/GadgetTools/
/vol/GadgetTools/.snapshot 4GB 0GB 3GB 1% /vol/GadgetTools/.snapshot
toaster> df -Ag aggr1
Aggregate total used avail capacity
aggr1 109GB 61GB 47GB 57%
aggr1/.snapshot 5GB 0GB 5GB 7%
toaster> vol offline GadgetData
Thu Sep 23 23:02:51 GMT [cifs.terminationNotice:warning]:
CIFS: shut down completed: CIFS is disabled for volume GadgetData.
Volume ‘GadgetData’ is now offline.
toaster> vol destroy GadgetData
Are you sure you want to destroy this volume? yes
Volume ‘GadgetData’ destroyed.
Notice that the vol size command above reduced the size of the volume down to 20GB. The ability to
reduce the size of a FlexVol volume is a new feature of Data ONTAP 7G.

Advertisements
Categories: netapp Tags: ,
  1. No comments yet.
  1. No trackbacks yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: