FlexClone splitting in Netapp OnTap 7

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I have a large volume containing only an NFS share I'd like to split up. 500GB of it (three specific subdirectories) needs to be put into a new volume. I'd like to avoid writing this data again. Here's what I think would work, but a colleague thinks that it won't work:

  • Flexclone the large volume
  • On a management server, mount the flexcloned volume and delete all the other subdirectories
  • Mount the original volume and delete the three subdirectories
  • Split off the clone

The way I understand it, when you split off a FlexClone, only the WAFL blocks with more than one pointer will get copied. In theory, I shouldn't have any (or many) of those. I'd be left with two non-linked volumes containing completely different data, and none of the 500GB would have been written.

Is this the case? If I split a FlexCloned volume after deleting some data from the source volume, will it copy those blocks?

Best Answer

This makes perfect sense - as you know the original data will reside on disk in it's original location and not be copied. Only the references to it will change:

FlexClone

Now you can delete the data you don't need in the respective locations, delete the snapshot (I think) and do a vol clone split:

Starts the process of splitting the FlexClone volume named Widget from its parent FlexVol volume. The split will make a copy of all blocks associated with the FlexClone volume that currently reside in the parent FlexVol volume. The process can take a while to complete and proceeds in the background. Afterward, the volume will be an independent FlexVol volume with space guarantees reenabled.

(if it doesn't let you delete the snapshot, you'll need to do the split first, resulting in copying the data)

source: http://www.redbooks.ibm.com/redpapers/pdfs/redp4133.pdf

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