NetWare 6.5 SP3 and earlier data pools are normally compatible for clustering purposes with NetWare 6.0, both backwards and forwards. The Media Manager changed between NetWare 6.0 and the initial release 6.5, but the media format is the same through NetWare 6.5 SP3. In NetWare 6.5 SP4 and later, you can optionally upgrade the NSS media format for enhanced hard links support.
If you move a device from the NetWare 6.5 SP3 or earlier server to a NetWare 6.0 server, and if you can see the NetWare 6.5 pool on the disk, but cannot activate it on your NetWare 6.0 server, the most likely causes might be a name conflict or that the pool was mirrored.
Pool and volume names must be unique on the server. Renaming the NetWare 6.5 pool should allow it to be activated on the NetWare 6 server.
If the pool was mirrored, the old media manager on NetWare 6.0 probably has problems with it because the information is different. You should remove the mirror before trying to move the disk to NetWare 6.0.
If you have upgraded the media format for hard links on a NetWare 6.5 SP4 or later server, you cannot move its NSS pool to a NetWare 6.0 server, or to any platform where the enhanced media format is not supported.