[pacman-dev] delta support in libalpm

[Aaron Griffin]

On Mon, Feb 23, 2009 at 5:58 AM, Xavier <shiningxc at gmail.com> wrote:
> On Mon, Feb 23, 2009 at 12:43 PM, Brendan Hide
> <brendan at swiftspirit.co.za> wrote:
>> Xavier wrote:
>>>
>>> how Garns answered to them:
>>> ...
>>> For Arch this would mean creating deltas on Gerolde, which seems to
>>> be fairly strained already.
>>> ...
>>> http://www.archlinux.org/pipermail/pacman-dev/2008-November/007672.htm
>>
>> Is Gerolde separate from the server that serves the FTP and HTTP traffic? If
>> it is
>> separate then I can't argue for the delta's improvement on the server's
>> performance.
>> If it *is* the same server then Garn's argument is illogical.
>>
>> What else is Gerolde doing for Arch and can it be moved to another server?

Gerolde does everything - every service that has an archlinux.org
domain name is hosted on gerolde (except ftp.archlinux.org). It can't
be "moved to another server" because we don't have another and don't
have the finances to get another at this time, nor do we have the
manpower to maintain multiple servers.

> This is not the only problem. Another big problem is that it would
> require real interest and work from official developers, and this is
> clearly inexistent :)
> For example, dbscripts would require some work as well
> http://projects.archlinux.org/?p=dbscripts.git;a=tree

I wouldn't say the interest is non-existent, it's just that the
implementation is so complex at this point in time, and most of us are
of the opinion that "bandwidth is cheap", so we go the easier route.

Questions which make the implementation complex:
* When do we generate deltas? As part of the db scripts?
* How long do we keep them? 10 previous versions? 5?
* How much additional space is this going to take? How do we set it up
so that space-constrained mirrors can opt-out of the deltas?

I'm sure there's more, but that's just "off the cuff". In my eyes,
this is a complex change that doesn't really seem to benefit too many
people. If you download 3megs instead of 7, it's not that big of a
deal and has so many more points of failure to contend with.