Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

See “Mirroring plus striping (striped-mirror, RAID-1+0 or RAID-10)”
on page 43.
■ RAID-5 (striping with parity)
See “RAID-5 (striping with parity)” on page 44.
Concatenation, spanning, and carving
Concatenation maps data in a linear manner onto one or more subdisks in a plex.
To access all of the data in a concatenated plex sequentially, data is first accessed
in the first subdisk from the beginning to the end. Data is then accessed in the
remaining subdisks sequentially from the beginning to the end of each subdisk,
until the end of the last subdisk.
The subdisks in a concatenated plex do not have to be physically contiguous and
can belong to more than one VM disk. Concatenation using subdisks that reside
on more than one VM disk is called spanning.
Figure 1-12 shows the concatenation of two subdisks from the same VM disk.
If a single LUN or disk is split into multiple subdisks, and each subdisk belongs
to a unique volume, it is called carving.
Figure 1-12
Example of concatenation
Plex with concatenated subdisks
Data blocks
Subdisks
VM disk
Physical disk
disk01-01
Data in
disk01-01
Data in
disk01-03
disk01-03
disk01-02disk01-01 disk01-03
devname
disk01-01 disk01-03
disk01
n n+1 n+2 n+3
n n+1 n+2 n+3
Understanding Veritas Volume Manager
Volume layouts in VxVM
36