Tape backup performance on 386 ISA/EISA systems

[Peter Gutmann]

In article <1990May31.155113.8383 at ico.isc.com> rcd at ico.isc.com (Dick Dunn) writes:
>davidsen at sixhub.UUCP (Wm E. Davidsen Jr) writes:
>[cpcahil at virtech.UUCP (Conor P. Cahill) cringes...]
>
>> | ...at the thought of letting someone's
>> | program hunt around my raw disk patching things together...
>
>>   True enough, but they are worth getting. Yes, I cringe when I run it,
>> but I take a backup first.
>
>But now we've come full circle...if disk fragmentation makes the backup go
>slower, so you want to run an optimizer that rearranges things, but you
>want to be careful, so you do a backup first...
>
>(Yeah, I know, the de-fragmenting does good for a lot more than just the
>backup.:-)
>
>A better approach is to use a file system that doesn't have as much
>tendency to fragment...sorry for the obvious plug.
>-- 
>Dick Dunn     rcd at ico.isc.com    uucp: {ncar,nbires}!ico!rcd     (303)449-2870
>   ...Simpler is better.

Well now we have come full circle. However one important thing
has been overlooked :-}

All of the tools required for disk de-fragmenting exist in the base
distribution of UNIX. All it requires are three simple steps,

1) create a backup of the device using your favorite backup utility 
   (such as tar or cpio). Don't use dump or any other utility which
   creates a "image" of the file system.

2) erase the contents of the devices that has been backed up
   in step one (above).

3) restore the device from the backup made above.

what this accomplishes is that the device has all of the blocks
in the file system moved to the free list. then reallocated sequentially
from the backup.

as Dick Dunn said above "..Simpler is better".

----
peter gutmann	peterg at murphy.com	

	Murphy & Durieu
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