[tex-live] revisions going backwards?

[George N. White III]

On Mon, Dec 29, 2008 at 9:38 AM, Lars Madsen <daleif at imf.au.dk> wrote:

> Oliver Heins wrote:
>>
>> "Yue Wang" <yuleopen at gmail.com> writes:
>>
>>>> bin-tlperl.win32: local revision (11607) is newer than revision in
>>>> http://mirror.ctan.org/systems/texlive/tlnet/2008 (10656), not updating.
>>
>> You're using mirror.ctan.org as source, which redirects to different
>> mirrors.  These mirrors might have different revisions, as they
>> synchronize at different times (today, mean mirror age is 6.3 days, but
>> median only 12 hours).
>>
>> You might find it easier to add an explicit mirror as your source:
>> Choose one from http://www.ctan.org/mirrors
>>
>> HTH,
>>  olli
>>
>
> I know, but that is one of the problems with tlmgr, it might be an idea that
> it actually explicitly mention which mirror it is looking at.

The command-line mode does:

$ tlmgr --location http://mirror.ctan.org/systems/texlive/tlnet/2008
update --all
tlmgr: installation location ftp://ctan.cms.math.ca/systems/texlive/tlnet/2008

With the GUI, if I use "change" to select the default location
"http://mirror.ctan.org/systems/texlive/tlnet/2008" then the actual
site is displayed as "Current installation source", in my case:

ftp://ctan.cms.math.ca/systems/texlive/tlnet/2008

> I usually end up at
>
> http://mirrors.dotsrc.org/ctan/systems/texlive/tlnet/2008/
>
> which has a list from 27 og december.
>
> But I have no way of knowing if this is the mirror it is looking at for the
> update.
>
> And explicitly specifying a mirror seems to contradict the idea of having
>  mirrors.

The whole mechanism is fragile.

Currently, the mirror mechanism appears to return a geographically "close"
server, which has several problems:

1.  net distance can be very different.   From Nova Scotia the net distance
to Europe is often less than to sites in the US and "upper" Canada.

2.  peak usage hours -- if you are updating during working hours, it may be
better to use a mirror site on the other side of the world.   During working
hours I generally have problems attempting to connect to the mirrors in
Ontario.

With Red Hat's yum updater, the downloader will try a mirror (seemingly at
random), and if that is not responding, switch to another.  In
practice this leads
to a slow start (so not good if you just have a couple small updates) but you
tend to end up with decent download rates for large updates.    The system
has to be robust to  cases where the mirror is missing some of the updates.
This has taken years of work to get to a reasonably robust tool.

I use a local mirror of the tlnet/2008 directory, with a mirror chosen
"by hand",
but quite often the mirror site is either not responding or not
current.   Here is
the list of recent site I tried:

Sun Dec 28 23:15:00 AST 2008
location ftp://ftp.math.purdue.edu/mirrors/ctan.org/systems/texlive/tlnet/2008
Mon Dec 29 09:46:02 AST 2008
location ftp://indian.cse.msu.edu/pub/mirrors/CTAN/systems/texlive/tlnet/2008

This gave the same list for "update --list"  same as purdue.

Mon Dec 29 10:04:54 AST 2008
location ftp://ctan.cms.math.ca/systems/texlive/tlnet/2008

This added 8 updates that weren't found on the purdue or msu mirrors, but
on a normal workday the chances of being able to connect are slim.  Furthermore,
(using the CMS mirror) I also get the:

bin-tlperl.win32: local revision (11607) is newer than the revision in
ftp://ctan.cms.math.ca/systems/texlive/tlnet/2008 (10656), not updating.

-- 
George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia