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

Creating Volumes

Creating a RAID-5 Volume

Chapter 7 239

NOTE Specify the -b option if you want to make the volume immediately

available for use. See “Initializing and Starting a Volume” on page 244

for details.

For example, to create the RAID-5 volume volraid together with 2

RAID-5 logs, use the following command:

# vxassist -b make volraid 10g layout=raid5 nlog=2

This creates a RAID-5 volume with the default stripe unit size on the

default number of disks. It also creates two RAID-5 logs rather than the

default of one log.

NOTE If you require RAID-5 logs, you must use the logdisk attribute to specify

the disks to be used for the log plexes.

RAID-5 logs can be concatenated or striped plexes, and each RAID-5 log

associated with a RAID-5 volume has a complete copy of the logging

information for the volume. To support concurrent access to the RAID-5

array, the log should be several times the stripe size of the RAID-5 plex.

It is suggested that you conﬁgure a minimum of two RAID-5 log plexes

for each RAID-5 volume. These log plexes should be located on different

disks. Having two RAID-5 log plexes for each RAID-5 volume protects

against the loss of logging information due to the failure of a single disk.

If you use ordered allocation when creating a RAID-5 volume on speciﬁed

storage, you must use the logdisk attribute to specify on which disks the

RAID-5 log plexes should be created. Use the following form of the

vxassist command to specify the disks from which space for the logs is to

be allocated:

# vxassist [-b] [-g diskgroup] -o ordered make volume length

\ layout=raid5 [ncol=number_columns] [nlog=number] \

[loglen=log_length] logdisk=disk[,disk,...]

storage_attributes

For example, the following command creates a 3-column RAID-5 volume

with the default stripe unit size on disks disk04, disk05 and disk06. It

also creates two RAID-5 logs on disks disk07 and disk08.