New Root Drive

Here's the system info: HP-UX 10.20 Dynamic Server 7.30.UC2 Here's the background: We upgraded our root disk drive from a 2GB drive to a faster 9GB drive, in order to have enough space to add the Y2K patches required by HP. Here's the problem: Since the upgrade Informix performance has gone to hell. Here's some more info: We have tried the new drive without the patches, and it is just as slow. So the patches are not the problem. We are running the exact same kernel, so that shouldn't be the problem. HP has suggested we look at the /dev/async device, but it is the same as the old drive. I have requested some info on this from Informix but they haven't gotten back. HP has suggested that we turn immediate reporting on for all drives, but this hasn't helped. If I look at disk I/O I can see some bottlenecks on some of the Informix drives, but they haven't been touched by the upgrade. Here's the question(s): What about the new drive could have affected the Informix drives and caused the bottlenecks? Has anyone else seen this? Does anyone have any experience with upgrading drives, and Informix performance? Here's the apology: I know this might be a system issue, but HP has not given me any help thus far. Also Informix tech support was unable to be of any help. Please let me know if any other information would be useful. Thanks in advance.