On 29/03/2010 09:39, Arthur Corliss wrote:
On Sun, 28 Mar 2010, dhu...@hudes.org wrote:
The entire point of rsync is to send only changes.
Therefore once your mirror initially syncs the old versions of modules is
not the issue. Indeed, removing the old versions would present additional
burden on synchronization! The ongoing burden is the ever-growing CPAN.
That's not entirely true, particularly when you're talking about rsync.
Remember, old synced data doesn't have to be transfered, but it still needs
to be checked for potential changes, something rsync does for every
request.
That generates a crap load of I/O in the form of stats on the server.
I believe cvsup (FreeBSD's source distribution mechanism) knows how to
avoid this cost by serialising context between runs.
That may be an avenue worth exploring, since it should be a less risky
proposition for a mirror operator to download a tried and true
technology rather than some pie-in-the-sky new system that may run out
of steam in a year's time.
David
The danger in a CPAN::Mini and in removing old versions is that one is
assuming that the latest and greatest is the one to use. This is false.
Take the case of someone running old software. I personally support
systems still running Informix Dyanmic Server 7.31 as well as systems
running the latest IDS 11.5 build. We have Perl code that talks to
IDS. If
DBD::Informix withdrew support for IDS 7.31 I would need both the last
version that supported it as well as the current. I can get away with
upgrading Perl, maybe, but to upgrade the dbms is much more problematic
(license, for one thing; SQL changes another).
This is a good example of the potentials of pruning, to be certain. Even if
all the authors dutifully documented all the necessary scenarios that would
require pinning specific versions on CPAN it's almost guaranteed that
there's still going to be collateral damage.
--Arthur Corliss
Live Free or Die
--
naked, but wearing blinding lights! were it a pretty girl, she'd be
surrounded as a flame by moths
