Re: What CDs and DVDs should we produce for lenny?
Uwe Bugla wrote:
[when answering a mail, please remove all uneeded quotes]
There is one basic error / misunderstanding in this last paragraph:
a. If you use ftp (file transfer protocol) or even http (hypertext transfer
protocol) the image is being treated like one big portion.
If download is going on it can be interrupted by backbone troubles or fallouts
for instance: That means that you can restart the download once again and you
lose an enormous amount of time. That really sucks!
> b. jigdo uses only a small amount of specialized dedicated servers for
> download, not every server in this world available at the moment.
> Moreover jigdo first writes a temporary image on your local hard disk,
> then executes the wget command and copies file by file to your hard
> disk. So if the download hangs for reason of force majeure (originally
> a french expression directly imported into the English language
> meaning "höhere Gewalt") you will not lose neither data nor time.
> If you restart jigdo after an interruption out of force majeure it
> will continue downloading at the point where the last jigdo download
> failed. This last point makes the big difference and advantage.
> So theoretically we can abolish hosting ISO images completely.
Once again, I will speak as a cdimage mirror admin. "Big" mirrors
usually have to deal more with disk load than with disk space (disk
capacity grows exponentially, sequential reads bandwidth grow is linear
and disk seeks barely decrease by a few percent over several years).
Thus, we have to optimize disk access to keep on with the load (ie read
more blocks per disk seek).
Downloading an ISO as "one big portion" let me read at once the biggest
block possible. Downloading an ISO using jigdo and accessing many
"small" files mean I will not be able to optimize anything. I would also
say that even after an interrupted download, you may restart it but not
all download softwares support this and some servers disable this
functionnality (in my case, it was disabled to block "download
accelerators"). Anyway, excepted for people with slow connections that
need many hours/days to complete a download and who may have to
halt/reboot their PC (or internet connection), an interrupted download
is quite uncommon and, if you have to optimize, take into account the
most common case.
As far as I am concerned, I would prefer ISO files only for "most needed
contents" (install/rescue ISO with main packages for standard
architectures)...
François
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