Re: db(3) removal and lastlogx

[David Holland <dholland-tech%netbsd.org@localhost>]

On Mon, Jun 11, 2012 at 08:46:21PM +0200, Manuel Bouyer wrote:
 >>>>> With 32bit uids, this will be very large files. We should avoid this.
 >>>> 
 >>>> Only if you carefully choose your UID space relative to the file
 >>>> system block size to maximize the amount of unused space that must
 >>>> nonetheless be materialized. That is foolish.
 >>> 
 >>> My UID space is not dense, but I meant large by what's displayed with ls 
 >>> -l.
 >> 
 >> And that's important how?
 > 
 > - people usually uses ls -l to find what could free some space on a full
 >  filesystem

They should know to use du.

 > - some tools don't deal with sparse files.

Which mostly doesn't matter. Especially with the lastlog file, which
is not exactly valuable data and can be (and routinely is) blown away
if a problem arises.

 > - once a block has been allocated, it won't ever be freed unless you kill
 >   the file.

It is easier to work around this than to worry about it, e.g. by
zeroing out lastlog records when accounts are removed, and then once a
year running a program that reclaims zero space as holes.

-- 
David A. Holland
dholland%netbsd.org@localhost