[mythtv-users] Software RAID and ionice

[Richard Freeman]

Is anybody using mythtv with software RAID and ionice?  I used to have a 
lot of problems with IOBOUND errors and frame dropping, until I 
discovered ionice and used it to prioritize mythbackend.  That fixed the 
problem - until I migrated my video directory to a RAID.  It seems like 
the RAID device ignores ionice settings.

I noticed that there is no equivalent to /sys/block/sda/queue/scheduler 
for dm or md devices.  I can set CFQ on the underlying hard drives, but 
I'm guessing those drivers just see a single md#_raid5 kernel process 
accessing data, so there is no prioritization.

Anybody else having issues with IO priority with software RAID?  I 
figured it would be relatively common on this list...