Pausing deletion of directories if load is high

Question

I have a list of directories that I'd like to delete. However when I do them all at one, load spikes on the box. Does anyone have an example of a script that would wait until load was under a certain level before proceeding with the deletion (interation of the loop)

Answer 1

Better still, use ionice.

ionice -c3 ./deletion-script

This'll cause your delete command only to run when the disk IO is free, so it has the lowest priority. Cyberciti has a nice little article on all the variants you have, and how to use them.

Answer 2

ionice is probably the best/simplest solution, but its only really delaying the inevitable and potentially just mean prolonged medium load versus a short run of high load.

There is a good write up here http://www.depesz.com/2010/04/04/how-to-remove-backups/ on a systematic controlled approach.

Changing the io scheduler, removing journals, atime and diratime are also contributory factors. There is also a different deletion binary fastrm , you can find the man here http://linux.die.net/man/1/fastrm

Don't try this at home

A while ago, we were testing faster deletion methods of deletion for terabytes of data. In the end it actually proved quicker to start a rm or mv then interrupt the process with ^c. Then restart the machine with a forced fsck - which then would clean up the inodes and free up the subsequent space on the file system.

It worked surprisingly well and far quicker than a traditional delete - but I would never ever do it on a production system. Ever.