Equivalent of `nice` for filesystem IO

My solution to this was a different two-pass approach, where I trade off some disk space. I do rsync --only-write-batch on the server, then rsync the batch file itself to the destination, looping until the rsync succeeds. Once the batch is fully over rsync --read-batch on the destination recreates all the changes.

There are some unintended benefits to this for me as well:

• because I'm more concerned that the backup "exists" than is "usable" I don't actually do the read-batch on the receiving end every day -- most of the time the batch is relatively small

• I've been experimenting with --checksum-seed=1 ... I might be mis-reading the documentation but I think it makes the batch files more syncable (ie. when I don't do the --read-batch any given day, the next day's batch syncs faster because the previous day's batch is a good basis)

• if the batch gets too big to send "in time" over the internet, I can sneaker-net it over on an external drive. By in-time I mean that if I can't get the batch over and read before the next day's backup starts.

• although I don't personally do this, I could have two offsite backups in separate locations and send the batch to both of them.

Why don't you try:

rsync -a /home/user/source /media/nas/destination

-a is convenience option specifically for archiving. It works for me all the time.

Here is what man page says:

-a, --archive archive mode; same as -rlptgoD (no -H)