[CentOS-mirror] Proposel - jigdo for iso Images

J.H. warthog9 at kernel.org
Fri Oct 30 06:52:00 UTC 2009

Uwe Kiewel wrote:
> Tru Huynh schrieb:
>> On Thu, Oct 29, 2009 at 02:59:22PM -0400, Nick Olsen wrote:
>>> Addition of jigdo yes. Replace ISO's no.
>>> Educating joe sixpack on using something new, well I like to use 
>>> altercation avoidance.
>> please no top posting ;)
>> There was a thread about jidgo in the archives and it boiled down to:
>> - someone has to maintain the jidgo package in the CentOS tree
>> (how would a CentOS user for C3/4/5 use jidgo?)
>> - document it in the wiki (how to use, at least)
>> - someone needs to make it work from the current setup
>> - how much burden will it put on the mirrors? centos.org ones and public ones?
>> (I have no experience on using it)
>> - no one volonteered.
>> - one more thing to check for the QA release process.
>> back to you :)
> Ok. Understood.
> It was just an idea because Fedora do it successfuly since Fedora 6 and 
> Debian do so as well.

Ok back that monkey truck up slightly here.  Fedora has *ONLY* been 
doing it for the Fedora Spins stuff which, as you can imagine, an 
*INCREDIBLY* low volume set of accesses.  Debian is going to be 
likewise, and I wouldn't exactly call it a popular thing from them.

Speaking as a mirror here are my thoughts:

- Cutting down on the working data set is a good thing, though I do have 
some serious reservations about this on a larger scale.

- Claiming a webserver doesn't handle large files is a bogus statement, 
if your on Linux you have send_file() and that is darned fast and 
efficient.  It more or less doesn't matter what your file size is for that.

- If your on a client, or a server, and it doesn't support http restarts 
you really have to ask why?  I can understand how *PAINFUL* that is to a 
mirror to do a random seek into the middle of a file, but once the 
download has started it's effectively no additional overhead beyond that.

- Speaking to the apache module that auto-generates the iso on the fly: 
any mirror of any reasonable size will shoot this down in a heartbeat. 
We already have an I/O problem on the systems, ram issues, etc.  Adding 
something into apache that's going to thrash about and magically 
generate this as it's requested is *WORSE* than the wasted disk space. 
Again send_file() is your friend.

My thoughts

Honestly if Centos is actively looking to eliminate the ISOs I would 
tentatively support this, but Jigdo (at least the last time I used it) 
is *ANYTHING* but userfriendly.  It would *HAVE* to be as simple as 
download a script, program, etc you get a download box and *poof* your 
dvd comes out, no user interaction unless a lot of advanced options are 
selected somewhere, and last time I used it it wasn't that simple.

Furthermore I think jigdo is likely going to be a lot of work, with 
little payoff.  From my gut reaction I think moving to more of a 
universal network installer (ala http://boot.kernel.org w/ it's network 
installers, which happen to include Centos)[Disclaimer: I'm one of the 
devs & the primary admin for http://boot.kernel.org] is a *LOT* more 
intuitive to a user and a lot simpler to get them to use than Jigdo ever 
will be, and honestly it gets a user moving sooner and it can take less 
time anyway depending on what a user selects, has all of the advantages 
of Jigdo and with significantly fewer downsides.

Just my $0.02

- John 'Warthog9' Hawley
Chief Kernel.org Administrator

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