U-Tools: Unique Tools for Windows System Administrators
Compaq RAID
Disk Controllers

Disk Array Controller

The Compaq SMART™ RAID disk array controller has a known problem where it sometimes will lose data when you reboot the computer. This includes pending changes to the registry.

During its operation, UPromote makes several changes to the registry and then reboots the computer. If some of these changes are lost, the NETLOGON service will fail to start and you will not be able to log on to your computer.

UPromote will warn you if it detects the presence of a Compaq SMART RAID disk array controller. This is explained in the README file and in our Frequently Asked Questions (FAQ) list under the topic Compatibility.

From the reports we have received, the problem seems to occur most often with RAID units manufactured in 1997-1999 with older ROMPAQ firmware and/or Compaq drivers. We recommend that you upgrade to NT Service Pack 6a and use the latest ROMPAQ firmware diskette and latest Compaq NT drivers for your RAID controller at www.compaq.com.

The problem will most likely occur if you install into your Compaq RAID controller a high performance disk drive that has a built-in memory cache. These drives (typically manufactured after 2001) can cache pending writes in a 2-16 megabyte memory buffer on the drive itself. When the Compaq RAID shuts down it kills the power on the drives without warning. The disk drive has no opportunity to write its memory cache to the disk platter. Any pending writes in the drive memory cache are simply lost. For this reason disk drives manufactured in 2001 or later cannot safely be used inside a Compaq RAID controller manufactured in 1999 or earlier.

Workaround for Compaq RAID

As a precaution UPromote will warn you if it detects any Compaq SMART RAID controller. If you wish to disregard the warning and run UPromote anyway, you can use the following procedure. (Note: Requires UPromote version 1.600 or later.)

  1. Run the Compaq Array Configuration Utility (ACU)
  2. Using the ACU, change the read/write caching percentage from 50%/50% to 100%/0%. This should effectively disable the write cache on the RAID controller.
  3. Append the override parameter -COMPAQ to PROMOTE.EXE. This will turn off the warning message and allow you to proceed.
    1. Press Start -> Run
    2. Type "C:\Program Files\UPromote\PROMOTE.EXE" -COMPAQ
      Note the explicit quotation marks ("")
    3. Press OK
  4. When you see the prompt to Press OK to reboot, stop and wait. Do not press the OK button right away. Wait at least 2 minutes to allow all disk activity to complete. Look at the disk activity lights to ensure that all disk activity has stopped. Only when all disk activity has stopped can you safely press OK. This allows the RAID controller to finish writing all the information to the disk. (After 2 minutes UPromote will proceed automatically.)

Our customers tell us that using the above procedure will avoid the problem. However we cannot vouch for the procedure because we do not have a Compaq RAID controller in-house to test it on. Again note that we do not officially support the Compaq SMART RAID disk array controller and we cannot help you if it loses registry modifications.