Veritas Volume Manager 4.1 Administrator's Guide (HP-UX 11i v3, February 2007)

Creating a Volume Using vxmake
218 VERITAS Volume Manager Administrator’s Guide
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 mydg04, mydg05 and mydg06. It also creates two RAID-5 logs on
disks mydg07 and mydg08.
# vxassist -b -g mydg -o ordered make volraid 10g layout=raid5 \
ncol=3 nlog=2 logdisk=mydg07,mydg08 mydg04 mydg05 mydg06
Note The number of logs must equal the number of disks specified to logdisk.
For more information about ordered allocation, see “Specifying Ordered Allocation of
Storage to Volumes” on page 205 and the vxassist(1M) manual page.
If you need to add more logs to a RAID-5 volume at a later date, follow the procedure
described in “Adding a RAID-5 Log” on page 243.
Creating a Volume Using vxmake
As an alternative to using vxassist, you can create a volume using the vxmake
command to arrange existing subdisks into plexes, and then to form these plexes into a
volume. Subdisks can be created using the method described in “Creating Subdisks” on
page 175. The example given in this section is to create a RAID-5 volume using vxmake.
Creating a RAID-5 plex for a RAID-5 volume is similar to creating striped plexes, except
that the layout attribute is set to raid5. Subdisks can be implicitly associated in the
same way as with striped plexes. For example, to create a four-column RAID-5 plex with a
stripe unit size of 32 sectors, use the following command:
# vxmake -g mydg plex raidplex layout=raid5 stwidth=32 \
sd=mydg00-01,mydg01-00,mydg02-00,mydg03-00