VERITAS Volume Manager 3.5 User's Guide - VERITAS Enterprise Administrator (June 2002)

VxVM Volumes
80 VERITAS Volume Manager User’s Guide - VEA
The following table summarizes the advantages and disadvantages of each volume
layout.
Layout Comparison
Layout Advantages Disadvantages
Concatenated
- The volume can consist of disk
regions that are not adjacent.
- The volume can span multiple
disks. A spanned volume can
have a greater capacity than a
single disk.
- The volume can be mirrored to
protect data against disk failure
and reduce the risk of data loss.
- There is a risk of data loss if the
volume is not mirrored.
- Spanning a volume across multiple
disks increases the chance that a
disk failure will result in the failure
of the volume.
- Concatenation does not improve
I/O performance.
Striped
- Striping provides improved
read and write performance.
- Striping can help to balance the
I/O load from multi-user
applications across multiple
disks.
- The volume can be mirrored to
protect data against disk failure.
- There is a risk of data loss if the
volume is not mirrored.
- Striping a volume across multiple
disks increases the chance that a
disk failure will result in the failure
of the volume.
- A striped volume requires at least
two disks.
RAID-5
- RAID-5 provides protection
against disk failure and reduces
the risk of data loss.
- RAID-5 provides data
redundancy by storing parity (a
calculated value) on the disks.If
a disk fails, the parity is used to
reconstruct the missing data.
- RAID-5 requires less storage
space than mirroring.
- RAID-5 providesimprovedread
performance.
- RAID-5 provides relatively slow
write performance.
- RAID-5 volumes cannot be
mirrored.
- A RAID-5 volume requires at least
three disks. If logging is enabled, a
RAID-5 volume requires at least
four disks.
- A RAID-5 volume cannot survive
multiple disk failures. However,
optional RAID-5 logs reduce this
risk.
- If one of the volume disks is
inaccessible, performance is
degraded.