Out of sync mirrors

Hi,
I am using linux 2.6.8 for my research on raid systems.

I need to have the disks of an array out of sync for a while.
I want to be able to stop a disk request queue (blk_stop_queue) and
start it sometime later. Meanwhile its mirrors should be serving r/w
as if this mirror was up.
Whenever the stopped mirror comes back it will serve all the requests
already sent to it.

I am queueing up the requests sent to all others while my mirror queue
is stopped.

The problem is that the other mirrors stop serving as well. Even if I
don't stop the queue, only delay its request a little bit, still the
others also slow down.

Question: how do I get raid to allow mirrors to be out of sync?

Obviously, I am missing something out in the code.

Any clues?

Thanks,
Ana Paula