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Re: Hammer clean up doesn't actually remove snapshots?

From: Thomas Nikolajsen <thomas.nikolajsen@xxxxxxx>
Date: Mon, 26 Apr 2010 14:07:05 +0200

>but if I access the removed snapshots with their old softlinks I still
>get them :-(

Accessing deleted snapshots gives undefined behavior.

If you try, you might see parts of directories and files;
anything between all and nothing might be 'missing'.

In general accessing @@TID symlinks for pruned ranges gives undefined behavior;
so if TID (Transaction ID) is not on a snapshot, or
is older (lower number) than your most recent snapshot, or
you are not within defined prune-min (PFS parameter) period,
hammer pruning & reblocking are allowed to delete historic data.
This is just what hammer cleanup does, wrapping up the task.

I think this is described in the manual pages hammer(8) & HAMMER(5):
. .
prune softlink-dir
	     Prune the file system based on previously created snapshot soft-
	     links.  Pruning is the act of deleting file system history.  The
	     prune command will delete file system history such that the file
	     system state is retained for the given snapshots, and all history
	     after the latest snapshot.  By setting the per PFS parameter
	     prune-min, history is guaranteed to be saved at least this time
	     interval. All other history is deleted.

If description is not clear, you are very welcome to suggest changes.


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