Thank you all for your comments. This has been an interesting discussion to follow.
My original incentive to change was performance. We're in a database I/O bottleneck situation, and hardware mirroring/striping should definitely help. I'm in the process of changing to it right now, and I'll report on the actual performance change when I'm done. Leigh: I am not using a battery-backed cache in the RAID controller. I have some fear that it could actually make corruption more likely in a hard crash situation. Better to allow the incomplete uncomitted transaction to roll back. We had previously changed to MIRRORWRITE DB PARALLEL to help performance - with a database shadow table. It did help. I assume that the shadow table will now be moot, and will not be used, once I finish undefining all the TSM-created mirror copies. Though I fear that this will be a slightly riskier configuration, I want very much to measure the performance difference, to see if the risk is worth it. It very well might be. There's only one way to find this out on a really big TSM database, and that is to try it. It's going to take another day to get there. Again, thanks to all for your input on a basic topic that matters. Roger Deschner University of Illinois at Chicago [EMAIL PROTECTED] "Panel on shouting-match TV shows ends in shouting match" --headline, Chicago Tribune, February 15, 2005