Packages make software installs and updates a lot easier. With packages, everything you install is atomic. If you have something like Abiword, that's in a package. When an update is available, you install the package for the new version. No "updates", no "patches". Just a whole new version.
That may seem like it could eat up a lot of bandwidth, right? But Linux distributions now use a system to reduce the update size. On Fedora Linux, that's done via yum-presto.
From the description:
Yum-presto is a plugin for yum that looks for deltarpms rather than rpms whenever they are available. This has the potential of saving a lot of bandwidth when downloading updates.But the key thing to remember is that you're still installing an rpm package. All that's changed is that you download a "diff" between one version and the next, and your system creates the rpm from the "diff". And you don't have to know anything about it to use yum-presto; it just there by default whenever you do an update.
A deltarpm is the difference between two rpms. If you already have foo-1.0 installed and foo-1.1 is available, yum-presto will download the deltarpm for foo-1.0 → 1.1 rather than the full foo-1.1 rpm, and then build the full foo-1.1 package from your installed foo-1.0 and the downloaded deltarpm.
Here's an example: I installed updates for my system yesterday, and (demonstrating the process for someone) happened to run the update from the command line. So I saw this message:
Presto reduced the update size by 77% (from 48 M to 12 M).
Rather than have to download 48 MB of packages to update, I only downloaded 12 MB. That saved me quite a bit of bandwidth - which is important, since I'm on vacation and the Internet connection here is very slow.
I've heard of this before, though I don't recall exactly where (it is entirely possible that it was yumpresto/deltarpm). It's a great idea though.
ReplyDeleteDo you know if APT/DEB-based distributions have a similar feature?
Thanks!
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a Linux Mint user since 2009 May 1
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This has been a standard feature since fedora 11 (current is fedora 12.) And it was available in fedora 10 if you set up your system config for it. A great add!
ReplyDeleteStrictly speaking, RPM is the package file format, rpm is the package manager program, and yum is the update manager program.
ReplyDeletePV, I've done some googling, and while I can find lots of discussion on, say, Ubuntu forums asking about a "delta-debs" concept, and some people even started thinking about it - I don't see anything that says "delta-debs" actually exist today. So I think the answer to your question is no.
ReplyDeleteBut I'm not an APT/DEB expert, so I don't know for sure. Maybe someone else here can correct me?
That was a neat post. I tried it for myself on my F12 box, at the command line, and got this for my latest set of updates {I haven't updated in a while}:
ReplyDeletePresto reduced the update size by 85% (from 30 M to 4.7 M).