Expanding existing Hammer FS

Michael Neumann mneumann at ntecs.de
Mon Dec 15 16:45:38 PST 2008


I'd be nice to be able to add just another spare disk to an existing 
Hammer FS to expand it's capacity. After taking a look at newfs_hammer,
it seems to be pretty easy to do that:

  * run format_volume on the new disk
  * ondisk->vol_num += 1 (number of volumes)
    for each volume of the filesystem.
I think that would be enough and I can hack it. My question is more 
API-oriented. How would the command line look like?

  How about this:

      hammer newfs label [... specify some defaults...]

  will create the following file:


  which will list all devices that make filesytem "label".

  Now add a volume:

    hammer add-volume label /dev/ad0

  This will format /dev/ad0 and attach it to the filesystem
  "label" by iterating over all volumes in /etc/hammer/label and
   increasing the volume count.
  Of course it would be more beautiful if the root volume would
  store those device names. That would also ease mounting of
  a multi-volume HAMMER fs:
    # create multi-volume Hammer FS
    newfs_hammer /dev/ad0 /dev/ad1
    # mount multi-volume Hammer FS by specifying the root volume
    mount_hammer /dev/ad0
    # add /dev/ad2 to the filesystem specified by the root volume ad0
    hammer add-volume /dev/ad0 /dev/ad2
Any suggestions?



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