Very poor latency when using hard drive (raid1)

[lkml@xxxxxxxxxxx]

There are 2 hard drives (normal, magnetic) in software raid 1
on 3.2.41 kernel.

When I write into them e.g. using dd from /dev/zero to a local file
(ext4 on default settings), running 2 dd at once (writing two files) it
starves all other programs that try to use the disk.

Running ls on any directory on same disk (same fs btw), takes over half
minute to execute, same for any other disk touching action.

Did anyone seen such problem, where too look, what to test?

What could solve it (other then ionice on applications that I expect to
use hard drive)?


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