faster rsync of huge directories

[Nadav Har'El]

On Tue, Apr 13, 2010, Tom Rosenfeld wrote about "Re: faster rsync of huge directories":
> > By the way, while "cpio -p" is indeed a good historic tool, nowadays there
> > is little reason to use it, because GNU's "cp" make it easier to do almost
> > everything that cpio -p did: The "-a" option to cp is recursive and copies
>...
> While we are on the topic, I use cpio because I am also "historic" :-) In
> the past I had to do similar  copies on diff versions of *NIX (even before
> rsync was invented!)

That's ok, because I am also "historic" :-) which explains why I even heard
of cpio (nowadays the only people who are likely to have even heard this
name are developers of RPM tools...). In the late 80's, I used cpio
extensively for transferring files across the atlantic on... diskettes.
I even remember one day when I arrived with a corrupt diskette, and had
to modify the cpio source code to skip over errors in the file. That day
I learned three lessons: 1. That open source rules, 2. That cpio sucks
as a backup format (because it has no error recovery capabilities) and
that there must be a better file transfer protocol than diskettes ;-)

Soon afterwards, I learned about tar and GNU cp. I haven't used cpio since...

> and after much testing of issues of hard links, sym links, timestamps, etc I
> found cpio to be the most portable tool. I guess when I get a chance I will
> test 'cp -au'

I just checked, and "cp -a" does seem to copy hard-linked files in a directory
correctly (i.e., the destination files are also hard-linked). I never checked,
though, if it can do more complicated hard-link copying. Frankly, I don't
really care - I stopped using hard links around the same time I stopped using
cpio. They were really important before the advent of symbolic links (in
System V release 4, if I recall correctly), but nowadays they are more often
confusing than useful - at least in my opinion.

-- 
Nadav Har'El                        |      Tuesday, Apr 13 2010, 30 Nisan 5770
nyh at math.technion.ac.il             |-----------------------------------------
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