Persistant PERC 4/DC failures losing up to 6 drives on a PowerVault 220S

I have a Dell 2850 running Windows 2003 Enterprise SP1 On this I have a PERC 4/DC SCSI controller
connected to Dell Powervault 220S.This has 14 drives configured for RAID 1 giving 7 logical drives.
This system has been up since 2006 with 1 drive failing until September 2014. Since then I have
had 6 similar failures. This chronic problem is becoming predictable.

In a short space of time I lose multiple disks. First of all I will get a  redundancy lost with 2 or
3 drives failing at the same time. Then within the space of an hour I will get 3 more disks failing
with the added headache of losing both drives for a logical disk. OpenManage states that the
PERC 4/DC has failed.

Since September I have changed just about every piece of hardware. Starting with the PERC 4/DC
controller to PERC 4/Di sister board. EMM controller cards on the PV220S and with the last failure
a month ago I changed the whole PV220S chassis. I thought I had cracked it as it ran for a month
before the last failure 3/4/15. The only piece of hardware I have not changed is the Dell 2850
itself but I cannot see the server being the root cause.

After failure I normally change out the PERC 4/DC controller and checked it on another machine and
it has been OK. I find it unlikely that many drives can fail at the same time so I force the
drives online and it carries out a check on the logical drives and states they are good.
I have changed 6 drives just as a matter of course.

Searching the web I found one comment where they state that it is possible for one bad drive to cause
this but still state that drive is OK. Has anyone heard of this? The last failure stated that a drive
had been removed and re-inserted but it did not check the re-inserted disk and one second later that
disks mirror failed with 3 other disks!?

I have updated all drivers and firmware to the latest Dell revision.LSI Logic Corp. had nothing
 to assist me.

We have other servers with the same controller but they are clustered drives, I have had issues
with this controller but nothing like this. This is a stand-alone server that holds SCADA historical
data. So very limited ability to change things arounds with this Microsoft SQL database.