in-situ conversion to FT disk config?

[Ben Scott]

On 11/17/05, Michael ODonnell <michael.odonnell at comcast.net> wrote:
> ... this indicates that if I had had the
>    presence of mind (and courage) to use something like "parted"
>    I could have done this with hda1 instead of hdc1, resized
>    that reiserfs filesystem inside that now-slightly-smaller
>    partition, shrinking it to fit and my original fantasy about
>    an in-situ RAIDification probably could have been realized.

  Better still is to resize the filesystem first, shrink the
partition, and then do the mirroring, as I mentioned earlier.  The
major problems with that are (1) resizing a filesystem can be as slow
as just coping it (and you still end up doing a full disk block copy
to create the mirror either way), and (2) resizing a filesystem is a
fairly risky operation.  A crash or power failure at the wrong time
will often destroy everything.

  So I generally recommend the safer route when it comes to this kind
of thing, especially since people doing this often don't have the
backups they should in the first place.  I also couldn't remember if
the Linux RAID metadata was kept at the start or the end of the
physical partition.  If it is created at the start of the partition,
one would have to not only resize the filesystem, but then *shift* it,
which is always slower then just coping files.

-- Ben