Re: Backing up a minix partition

[Christian Lynbech <lynbech@daimi.aau.dk>]

>>>>> "Stephen" == Stephen Usher <Stephen.Usher@earth.ox.ac.uk> writes:

>>> Install one of the raw floppy drivers, such as ps0.
>>> 
>>> The command: gtar czvMf /dev/ps0 /foo/bar will then backup the
>>> directory /foo/bar as a multi-volume gzipped raw archive.  It will
>>> prompt you for each disk.
>>> 
>> Ok, I've tried that. Using GNU tar version 1.11.2 I get:
>> 
>> gtar: cannot use multi-volume compressed archives
>> 
>> Now that's a shame. I really don't like backing up my harddisk
>> without compression (which does work BTW).

Stephen> Surely you mean the other way around.. I'd never trust a
Stephen> compressed backup as one fault in the media will cause far
Stephen> more damage. Indeed with compressed archives it's usually
Stephen> impossible to recover anything from a corrupted volume.

Sure, but backing even just a 20Mb harddisk up on floppy disks are a
tedious affair involving ~30 floppies with a full disk. Using
compression should reduce it to at ~15, perhaps even lower. It can be
hard resisting the temptation, given lack of money for a tape-streamer.

On the other hand, there is usually a smaller number of files which
changes frequently (try comparing the size of your home directory with that
of /usr/bin), so one could do a full backup using compression, and
incremental backups without.

>> Perhaps you are using a more recent version (if any) of gtar.
>> Otherwise I'll just have to look for another solution (if any),

Stephen> I believe I know why compressed multi-volume backups are not
Stephen> supported..  gtar merely pipes the data through gzip so can't
Stephen> easily tell if it's getting to the end of a volume.

It should be no big problem to create a small utility that reads form
stdin and outputs a specified number of bytes to stdout, request the
user to type return and then proceed.

Then one could do something like:

  gtar czMO / | chop 716800 | /dev/ps0


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Christian Lynbech               | Hit the philistines three times over the 
office: R0.33 (phone: 3217)	| head with the Elisp reference manual.
email: lynbech@daimi.aau.dk	|        - petonic@hal.com (Michael A. Petonic)
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