Dump time issues

[David Wolfskill]

On Sat, Oct 25, 2014 at 01:26:43PM +0200, Alban Hertroys wrote:
> I?m seeing something odd in my dump output that I didn?t notice before:
> 
> Dumping /root...
>   DUMP: WARNING: should use -L when dumping live read-write filesystems!

(That, by the way, is pretty good advice in my experience.)

>   ...
>   DUMP: dumping (Pass IV) [regular files]
>   DUMP: 2.43% done, finished in 3:20 at Sat Oct 25 16:09:41 2014
>   DUMP: 5.35% done, finished in 2:57 at Sat Oct 25 15:51:18 2014
>   DUMP: 6.98% done, finished in 3:19 at Sat Oct 25 16:19:11 2014
>   DUMP: 9.14% done, finished in 3:18 at Sat Oct 25 16:22:57 2014
>   DUMP: 11.98% done, finished in 3:03 at Sat Oct 25 16:12:54 2014
>   DUMP: 14.35% done, finished in 2:59 at Sat Oct 25 16:13:20 2014
> 
> Note that the time is jumping back and forth and that these times are several hours into the future:
> 
> $> date
> Sat Oct 25 13:16:05 CEST 2014
> ....

Sure; they are estimates.

They are issued every 5 minutes or so; the first is an estimate that the
dump will take 3.33 hrs. (3:20) more time, and thus complete at 16:09:41.

The second (5 minutes later) estimates that it will only take 2:57 more,
and thus complete at 15:51:18; this pattern continues.

dump(8) tends to require varying amounts of time to process a file
system, depending on the population of files where it is working --
e.g., lots of tiny files, vs. a smaller number of large files; file
where all the data blocks are "near" each other, vs. those where blocks
are scattered all over the file system.  It is thus normal for the
estimates -- especially the earlier ones -- to vary considerably.

Peace,
david
-- 
David H. Wolfskill				david at catwhisker.org
Taliban: Evil cowards with guns afraid of truth from a 14-year old girl.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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