Problems with LVM and "scsi add-single-device"

[Michael Dr|ing]

Hi,

we're having problems using LVM (see end of mail for version numbers) together with the "scsi add-single-device"-feature:
We have an external RAID which responds on three SCSI-LUN's: ID 2, LUN 0 to 2. On LUNs 0 and 1 we have created PVs and mapped them into one LV. Now we wanted to extend our filesystem (XFS) on the third LUN without bringing the system down.
We did an "echo scsi add-single-device 2 0 2 2 > /proc/scsi/scsi" to make the kernel recognize the new LUN. But after that all calls to "pvscan" or "pvcreate" or even "vgscan" failed. They slow down the system extremely and we have to interrupt them with Ctrl-C.
Anyone got an idea what the problem might be?

Thanks
--Michael

Here are some version numbers of our system:
Linux 2.4.10 (base system is SuSE 7.1 with SGI XFS kernel built from CVS-tree)
LVM 0.9.1 beta 6 (however, the user programs [pvscan, pvcreate, ...] are from beta 7)
aic7xxx driver 6.2.1 (that's our SCSI adapter)