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I have a problem in a server that has several dozen snapshots of a ZFS fileset. Back in November we received files that turned out to be for another organization. The content of the files is very sensitive, so the files were deleted. However, by the time we deleted the files, some 42 snapshots had been created of the fileset that contain data or references to those files.

The problem now is that we have to remove that data from the snapshots but we do not want to lose the rest of the contents of the snapshots. Everything I have read so far about ZFS snapshots is that they are all-or-nothing entities. You can create them and destroy them but not modify them to partially remove contents.

Is that indeed the case, or does anyone know of a solution for this?

Juan Jimenez
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  • While snapshots are indeed read-only, clones are not. Do you think a snapshot-clone-modify-[promote] sort of scheme could work? – airhuff Feb 01 '17 at 22:11
  • I don't know. In the end we decided that since we have a huge tape backup automated system coming on line next month we will wait for that and let the snapshots expire on the basis of the normal policy. – Juan Jimenez Feb 03 '17 at 07:49

1 Answers1

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You won't be able to remove the data from the snapshots without altering the other snapshots in size.

Maybe it makes sense to remove the unnecessary snapshots. You CAN modify snapshot data, but I'm not sure what your specific concern is. Is it space? Will these snapshots age-out after some period of time?

ewwhite
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  • The customer does not want to lose all of those snapshots. There are 42 of them and they are all the most recent. The concern is that the data received incorrectly must be entirely purged from our storage, including the ability to restore it from snapshots. – Juan Jimenez Jan 18 '17 at 07:04
  • "You won't be able to remove the data from the snapshots without altering the other snapshots in size." <- How would you do that? Space is not really a concern, because the affected files should all be removed (in any snapshots where they are present). – user121391 Jan 18 '17 at 08:06
  • Precisely. Storage space is not a concern in this case. – Juan Jimenez Jan 18 '17 at 10:31