[sf-lug] Tried zsync for an Ubuntu ISO update and liked it

[Ken Shaffer]

Ubuntu 16.04 is days from final release, and I thought I'd update my
month-old
16.04 beta2 ISO.  I'd never tried the ISO-update capability offered by the
zsync
utility, so I gave it a try.  After a false start because I didn't give the
(changed) old ISO name, the download went to 75% when the network dropped.
Restarting used the partially downloaded information as a starting point,
and
the zsync download finished, and confirmed the checksum.  Only 360M needed
to be downloaded, since the other 1.1G was unchanged from the beta2.  I'm
happy with zsync and I'll be using it for my future ISO updates.
Ken

$ ls -l
total 1547140
-rw-rw-r-- 1 user1 user1 1581383680 Mar 25 10:19
ubuntu-16.04-beta2-desktop-amd64.iso

$ zsync
http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso.zsync
#################### 100.0% 513.2 kBps DONE

No relevent local data found - I will be downloading the whole file.
If that's not what you want, CTRL-C out. You should specify the local
file is the old version of the file to download with -i (you might have
to decompress it with gzip -d first). Or perhaps you just have no data
that helps download the file
downloading from
http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso:
-------------------- 0.0%^C


$ zsync -i ubuntu-16.04-beta2-desktop-amd64.iso \

http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso.zsync
#################### 100.0% 676.4 kBps DONE

reading seed file ubuntu-16.04-beta2-desktop-amd64.iso: *********<snip>
***********Read ubuntu-16.04-beta2-desktop-amd64.iso. Target 56.1%
complete.      ******
Read xenial-desktop-amd64.iso.part. Target 56.1% complete.
downloading from
http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso:
###########--------- 56.1% 0.7 kBps
###########--------- 56.1% 8.7 kBps
###############----- 75.5% 1187.5 kBps 5:07 ETA  cdimage.ubuntu.com:
Connection timed out
cdimage.ubuntu.com: Network is unreachable
###############----- 75.5% 909.8 kBps aborted

failed to retrieve from xenial-desktop-amd64.iso
Aborting, download available in xenial-desktop-amd64.iso.part
verifying download...user1 at comp:/usr/local/vm/xenial$ ls -l
total 2634328
-rw-rw-r-- 1 user1 user1 1581383680 Mar 25 10:19
ubuntu-16.04-beta2-desktop-amd64.iso
-rw------- 1 user1 user1 1474953216 Apr 20 10:07
xenial-desktop-amd64.iso.part

$ zsync -i ubuntu-16.04-beta2-desktop-amd64.iso \

http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso.zsync
#################### 100.0% 423.1 kBps DONE

reading seed file ubuntu-16.04-beta2-desktop-amd64.iso: *****<snip>******
Read ubuntu-16.04-beta2-desktop-amd64.iso. Target 56.1% complete.
******
reading seed file xenial-desktop-amd64.iso.part: *****<snip>*****
Read xenial-desktop-amd64.iso.part. Target 75.5% complete.
********************
downloading from
http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso:
##################-- 91.5% 405.0 kBps

downloading from
http://cdimage.ubuntu.com/daily-live/current/xenial-desktop-amd64.iso:
#################### 100.0% 428.5 kBps DONE

verifying download...checksum matches OK
used 1113337856 local, fetched 362086800

$ ls -l
total 2987596
-rw-rw-r-- 1 user1 user1 1581383680 Mar 25 10:19
ubuntu-16.04-beta2-desktop-amd64.iso
-rw------- 1 user1 user1 1474953216 Apr 19 23:06 xenial-desktop-amd64.iso

And checking the md5sum manually:
from the site:
614e2201e42ceb77bc2eba5e6358bf67 *xenial-desktop-amd64.iso

The zync download:
$ md5sum xenial-desktop-amd64.iso
614e2201e42ceb77bc2eba5e6358bf67  xenial-desktop-amd64.iso
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