VxVM 4.0 onwards introduced DMP filesystem (dmpfs) - this is used for the dmp metanodes/metadevices that map to the underlying OS devices.
The following extract is from a Linux technote - exact details may differ slightly depending on OS, but the overall principle is the same
from: VERITAS Storage Foundation (tm) and Storage Foundation HA 4.0 for Linux - An Introduction (
VERITAS Storage Foundation (tm) and Storage Foundation HA 4.0 for Linux - An Introduction )
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DMP File System
The total number of disk devices (including partition devices) that are supported by the Dynamic Multipathing feature (DMP) is no longer limited to 255. This is made possible by the introduction of the dmpfs file system, which supports more than 4 billion disks with 16 partitions per disk on a system. This is many more than the number of disk devices that Linux typically supports. (This limitation is expected to be removed when the 2.6 version kernel is introduced.)
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The "filesystems" are created as part of the installation process (ie: will see them in df -k output after VxVM is installed / loaded onto the system)
