Hammer - adding volume
dillon at apollo.backplane.com
Wed Jul 16 09:34:36 PDT 2008
:Is adding a volume to an existing filesystem
:going to be supported for the release?
:I guess I will have to use newf_hammer with some flag
:to prepare new volume for addition to existing filesytem,
:but don't see appropriate flag.
:When I just newfs_hammer another partition, it can't be mounted with existi=
:mount fails with this message to console:
: fsid doesn't match other volumens
Heh, that won't work. HAMMER will not let you shoot yourself in the
foot, if you specify two separate HAMMER filesystems in a single mount
it won't let you do it.
It won't be available for release but certainly messing around
with the volume structure off-line (with the filesystem unmounted)
is not too difficult to do and you could write a command to have
the hammer utility do it. Basically:
* You have to create a new volume header in the new partition,
assign it a new volume number (e.g. original might be volume 0,
your new volume would be volume 1), and assign it the same
fsid. Numerous fields must be properly assigned.
* You have to update all the volume headers to specify that there are
two volumes in the filesystem.
* And finally the freemap needs to be updated to add the space now
available in the new volume to the filesystem. The freemap's
layer1 is already allocated so this is a matter of allocating and
assigning the layer2 big-blocks related to the new volume.
<dillon at backplane.com>
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