Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

41Understanding Veritas Volume Manager
Volume layouts in VxVM
The layout type of the data plexes in a mirror can be concatenated or striped. Even if only
one is striped, the volume is still termed a mirrored-stripe volume. If they are all
concatenated, the volume is termed a mirrored-concatenated volume.
Mirroring plus striping (striped-mirror, RAID-1+0 or RAID-10)
Note: You need a full license to use this feature.
VxVM supports the combination of striping above mirroring. This combined layout is
called a striped-mirror layout. Putting mirroring below striping mirrors each column of
the stripe. If there are multiple subdisks per column, each subdisk can be mirrored
individually instead of each column.
Note: A striped-mirror volume is an example of a layered volume. See “Layered volumes”
on page 47 for more information.
As for a mirrored-stripe volume, a striped-mirror volume offers the dual benefits of
striping to spread data across multiple disks, while mirroring provides redundancy of data.
In addition, it enhances redundancy, and reduces recovery time after disk failure.
Figure 1-18 shows an example where a striped-mirror volume is created by using each of
three existing 2-disk mirrored volumes to form a separate column within a striped plex.
Figure 1-18 Striped-mirror volume laid out on six disks
See “Creating a striped-mirror volume” on page 247 for information on how to create a
striped-mirrored volume.
As shown in Figure 1-19, the failure of a disk in a mirrored- stripe layout detaches an
entire data plex, thereby losing redundancy on the entire volume. When the disk is
Striped plex
Mirror
Striped-mirror
volume
Underlying mirrored volumes
Column 0 Column 1 Column 2
Column 0 Column 1 Column 2