rsync takes long pauses in xfer ?

[Alan McKay]

On Tue, Jun 12, 2012 at 9:39 AM,  <ericbambach1 at discover.com> wrote:
> Alan,
>
>        What is the rsync command used? If it hits a large group of files
> with no differences (easy to believe across 12TB) but has to compare the
> checksums anyways (forced by you or failing the size+time compare) you'll
> be I/O bound with almost no corresponding network traffic as it just has
> to send the checksums.

Here is what shows up in the process list.
BTW this is running Ubuntu 12.04 Live USB stick.  But I saw the same
behavior on the same machine last week on RHEL5.

0 R root     20991 20986 15  80   0 - 51725 -      Jun11 pts/2
03:05:18 /usr/bin/rsync -a --delete --numeric-ids --relative
--delete-excluded --include-from=/usr/local/etc/rsnapshot.d/include
--exclude-from=/usr/local/etc/rsnapshot.d/exclude /data
/mnt/1J4400/rsnapshot/daily.0/ZFS/
5 S root     20992 20991  0  80   0 - 48034 poll_s Jun11 pts/2
00:00:34 /usr/bin/rsync -a --delete --numeric-ids --relative
--delete-excluded --include-from=/usr/local/etc/rsnapshot.d/include
--exclude-from=/usr/local/etc/rsnapshot.d/exclude /data
/mnt/1J4400/rsnapshot/daily.0/ZFS/
5 R root     20993 20992 16  80   0 - 59897 -      Jun11 pts/2
03:14:28 /usr/bin/rsync -a --delete --numeric-ids --relative
--delete-excluded --include-from=/usr/local/etc/rsnapshot.d/include
--exclude-from=/usr/local/etc/rsnapshot.d/exclude /data
/mnt/1J4400/rsnapshot/daily.0/ZFS/