The device-mapper mirror target is putting out a status string that has trailing white-space. This is causing target tables to be loaded multiple times for the same device during LVM operations like lvconvert and lvrename, because LVM is doing a simple string comparison. Loading multiple identical tables causes serious problems with cluster mirroring especially. This issue is not severe, as the work-around in user-space is trivial. However, it should be fixed in the kernel. The attached patch is being push upstream.
Created attachment 135873 [details] Patch to fix status output of device-mapper mirror target
There is a work-around in userspace for this in RHEL4. This has been fixed in RHEL5/upstream.
Workaround in RHEL4.4 Fix in RHEL 5.0 (and also present upstream)