DragonFly bugs List (threaded) for 2008-07
Re: Another HAMMER crash
Matthew Dillon wrote:
:Yes, that helped.
:> I recommend always doing a normal mount and using cd @@0x<TID> to
:> push into a snapshot.
:I had no snapshot. I just wanted to try the as-of mount. I read the
:manual but failed to understand it. hammer(5) says:
:'Prior versions of files or directories are accessible by appending @@
:and a transaction ID to the name.'
:I could not access them this way.
:Gergo Szakal MD <firstname.lastname@example.org>
:University Of Szeged, HU
You can generate the transaction ids manually using 'hammer synctid',
or you can extract them from a file using 'undo -i <filename>'. You
get a snapshot every 30-60 seconds even if you don't lift a finger,
but unless you record the transaction ids somewhere you'd have to
do some sleuthing (e.g. with undo -i) to get them.
Typically what you would do is have a cron job create a convenient
snapshot softlink once an hour, once a day, whatever, like this:
hammer snapshot /mnt/snapshots
hammer snapshot /mnt/snaphots/SNAP-%Y-%M-%H
Which would generate a symlink
The first argument to "hammer snapshot" takes a template similar to
strftime(3), so you can generate snapshots with:
If /mnt/snapshots itself is not on a hammer filesystem you should as
well specify the hammer filesystem to snapshot:
hammer snapshot /mnt/snaphots/SNAP-%Y-%M-%H /hammer