Another HAMMER crash

[Michael Neumann]

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 <bastyaelvtars at gmail.com>
: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:
    mkdir /mnt/snapshots
    hammer snapshot /mnt/snapshots
The first argument to "hammer snapshot" takes a template similar to
strftime(3), so you can generate snapshots with:
  hammer snapshot /mnt/snaphots/SNAP-%Y-%M-%H

Which would generate a symlink

  /mnt/snapshots/SNAP-2008-08-25

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

Regards,

  Michael