How to make PERC 3/DI work under load?

  Hello.
  
  I'm in charge of some Dell servers with a PERC 3/DI controller and these
hosts have serious disk I/O issues.

  With little disk I/O, the controller properly works.
  
  But as soon as the traffic increases, the system load grows up to 500 and
the whole system stops working (all Apache threads are waiting for I/O until
the max number of clients is reached and no more connection is accepted).
Other servers running the same OS but with basic IDE discs don't have that
bottleneck.

  Kernel is 2.6.0. I tried 2.6.0-test11-mm1 and all elevators with no big
improvement.

  There are two RAID-1 (hardware RAID) 134 Gb discs.
  
  The RAID firmware and the mobo BIOS are up-to-date.
  
  There is no kernel panic, disk I/O is just extremely slow. Also when it
occurs, sync(2) is very long to complete.
  
  What do you suggest to fix the situation?
  
  Is the issue fixed in aacraid-1.1.4.2225 (2.6.0 ships with aacraid-1.1.2)?
  Did anyone forward port the official driver to 2.6 kernels?
  Would changing AAC_NUM_FIB to AAC_NUM_IO_FIB+64 be enough (and safe with
write caching turned on)?

  Best regards,

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