[Dump-devel] Feature Creature -- Exclusion List

[PeterKorman <cal...@ei...>]

With reasonably small changes, a
dump exclusion list of nearly unlimited size
could be supported.

It would mean an internal binary search to
interrogate the exclusion list during file write
and a reasonably good performance sort routine
to put the exclusion list in order to make the 
binary search possible. A heap sort would give
order O log N worst case performance. After the
sort a quick walk through the list to trim any
duplicate entries would be a low cost operation 
as well.


Price performance on Tape drives is awful.
OTOH a big ATA disk is fast and comparably
cheap. In many cases, systems never need to
hold more than 3 L0 dumps each 19 days apart.
The thing about backing up to an non-removable
drive is that you really dont want to back up 
anything you don't have to back up. Web browser
cache directories, for instance, never need 
backing up.  Mailing lists often dont need backing 
up.

You can partition file systems so that the junk
goes to those not backed up, but that also limits
flexibility of storage utilization.

So if you have 2 60G drives, and the first one
is 15% transient junk, then you can be pretty
safe doing compressed dumps to the second drive.
Big exclusion lists become pretty important because
there's LOTZ of small transient files. A fast
search is especially important if you have say
500000 files in a L0 dump, of which you 
want to exclude 170000.


My 3 questions are these:

Does anyone think the maintainer would be
interested in a patch like the one I describe?

If so, where would the person who generates
the patch send it?

How much time might pass between submission
of the patch and it's inclusion in the 
distribution assuming the patch is worth
a damn? Thanks.


Cheers,

JPK