xen-org/xen-api — pull request #718 by djs55 (2012-07-01 21:45:13+00:00)
Title: CA-84843: Add request pipelining to sparse_dd

By sending multiple requests we can increase the throughput, from 40 MiB/sec to 80 MiB/sec on my local SATA disk.

Use a config file to allow the number of requests (default 8) to be tweaked easily to match future environments.

Tested by:
1. manually invoking sparse_dd on the commandline, verifying that the copy terminates, is faster with 8 parallel requests than with 1, and the resulting disks have matching md5sums
2. checking that storage motion still works (local lvm to local lvm and back)
3. quicktest (just in case)