AIX & Large disk drives.

This is a fairly large database site. We are using AIX version 3.2.5 and Informix Online Version 5.03.UC2. There are several 4.5Gb SCSI Differential disk drives (primaries) and their associated mirrors. Each of the drives is setup with its own volume group. Physical partition (PP) sizes were set at 4Mb ( the AIX default w/o the patch). We have been having a problem keeping one of the mirrored drives up. The Informix logs report that there is a problem with one of the SCSI cards. The AIX logs indicate that there is a problem with addressing some pages on the mirrored drive. Now the problem. AIX 3.2.X and releases prior to 4.1.3 have this problem and need a new patch of you are planning to use 4.016Gb drives or larger. AIX Technical support informed me that there is a limitation on the number of physical partitions that can be addressed by a particular volume group. The number is 1016. If your physical partitions size is 4Mb then this limits your drive size to 4.016Gb. See the documentation for APAR IX48928 and IX50489. This patch changes smit so that any new drive created will have an appropriate (larger) PP size. IBM support is "recommending" that I recreate all the volume groups using a different PP size. I find this a bit hard to swallow. My questions are: 1. Can the mirrored partitions be larger physically than the primaries ? and also have a different PP size? I'm not too worried about a small amount of wasted space. 2. Does the physical partitioning (PP) size have any impact on how Informix addresses drives these devices ? 3. Is there any information stored in the level 0 backup relating to the PP size or does it simply dump consecutive pages? 4. Why am I encountering this addressing problem on only one drive ( a mirror ) and not all of them ? 5. Does anyone else have related experience or information that might be helpful? Thanks is advance. Please reply to : muhlenberg_john@prc.com or to this news group. ------------------------------------------------------------------------------------------------- The opinions expressed above are my own and not those of my company. --------------------------------------------------------------------------------------------------