I have not used this myself but came across it and thought it was worth sharing:
File:Indimail queue.png - Wikipedia, the free encyclopedia
Generally the faster your disks the faster your qmail. If instead of having 1 large set of fast disks you had several smaller mirrors on disks I suppose it's possible this could be a way to help deal with incoming loads instead or in addition to the ext-todo patch. Like I said, not a recommendation, just thought it was worth sharing.
File:Indimail queue.png - Wikipedia, the free encyclopedia
Generally the faster your disks the faster your qmail. If instead of having 1 large set of fast disks you had several smaller mirrors on disks I suppose it's possible this could be a way to help deal with incoming loads instead or in addition to the ext-todo patch. Like I said, not a recommendation, just thought it was worth sharing.