Here's an example.
dest = directory tree full of files all interdependent. a change in one
without the corresponding change in another makes the whole tree invalid.
If you just rsync the directory changes over, the tree is invalid from the
first change is started until the last one is done.
To avoid this, you rsync to another directory in the same filesystem,
using --compare-dest to point to the actual directory.
Once the new copy is finished, you rename the original to a temporary
name, rename the new copy to the originals name (these two operations are
nearly instantaneous), then recursively delete the original directory.
This way, there is no time at all where the directory is invalid, and only
maybe a millisecond where it doesn't exist.
Tim Conway
[EMAIL PROTECTED]
303.682.4917
Philips Semiconductor - Longmont TC
1880 Industrial Circle, Suite D
Longmont, CO 80501
Available via SameTime Connect within Philips, n9hmg on AIM
perl -e 'print pack(nnnnnnnnnnnn,
19061,29556,8289,28271,29800,25970,8304,25970,27680,26721,25451,25970),
".\n" '
"There are some who call me.... Tim?"
[EMAIL PROTECTED]
Sent by: [EMAIL PROTECTED]
01/28/2002 06:02 AM
To: [EMAIL PROTECTED]
cc: (bcc: Tim Conway/LMT/SC/PHILIPS)
Subject: --compare-dest option
Classification:
I'm translating rsync.1, and i'm having some problems with the
--compare-dest option description, actually i dont understand the part
which describes the usefulness of this option, it says :
This is useful for doing transfers to a new destination while leaving
existing files intact, and then doing a flash-cutover when all
files have been successfully transferred (for example by moving
directories around and removing the old directory, although this
requires also doing the transfer with -I to avoid skipping files
that havenīt changed).
If someone could explain me this (especially the flash-cutover thing) ,
maybe with a little example, it would greatly help me for the translation.
Thanks in advance
Denis
