Jaimie Vandenbergh wrote:
On Tue, 04 Nov 2008 08:12:08 +0000, Alex Fraser <me@xxxxxxxxxxx>
Syncing a single 600MB file cached in RAM to an empty directory, it
reports around 50MB/s here - that's using a daemon connection rather
than running over ssh and seems to be near the limit of both destination
CPU and drive.
Nice - thanks, I'll go grab a copy.
Hmm. I see it's just a package with cygwin bits included. The rsync
that comes with cygwin was one of the slow ones on my previous tests,
pointing at a destination linux rsyncd. I'll give it a go.
I'd be interested to know how you get on. What are the machine specs like?
rsync -aFhhW --stats --delete-excluded --delete-during $src $dest
(Note -W: I found it slightly quicker to disable the delta transfer
algorithm over gigabit Ethernet; it uses more bandwidth but that's not
an issue for me.)
That's certainly interesting.... I guess at 50meg/second on gigE it
takes longer to scan at both ends, block-crc, compare, then send diff
blocks than it does to just send. It may make a difference to backing
up eg VM images, and (ick) large Outlook databases though.
My "slightly" above is based on handling renames - so basically checking
two files are the same and then renaming the destination. Updated files
may be rewritten rather than changed in-place under some circumstances;
this will be far slower than simply replacing the file unless the
destination is a fast RAID setup.
One way of looking at it is to note that delta transfers are turned off
by default for local syncs, and going over gigabit Ethernet is more like
local than even a 100Mbit network.