VERITAS Volume Manager 3.5 Administrator's Guide (September 2004)

Understanding VERITAS Volume Manager

Volume Layouts in VxVM

Chapter 1 27

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 1-19, “Striped-Mirror Volume Laid out on Six Disks,” 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 1-19 Striped-Mirror Volume Laid out on Six Disks

See “Creating a Mirrored-Stripe Volume” on page 234 for information on

how to create a striped-mirrored volume.

As shown in the ﬁgure, “How the Failure of a Single Disk Affects

Mirrored-Stripe and Striped-Mirror Volumes,”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 replaced, the entire

plex must be brought up to date. Recovering the entire plex can take a

substantial amount of time. If a disk fails in a striped-mirror layout, only

the failing subdisk must be detached, and only that portion of the volume

loses redundancy. When the disk is replaced, only a portion of the volume

needs to be recovered. Additionally, a mirrored-stripe volume is more

Striped Plex

Mirror

Striped-Mirror

Volume

Underlying Mirrored Volumes

Column 1 Column 2 Column 3