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242 Creating volumes
Discovering the maximum size of a volume
max_nstripe=8
min_nstripe=2
# for RAID-5, by default create between 3 and 8 stripe columns
max_nraid5stripe=8
min_nraid5stripe=3
# by default, create 1 log copy for both mirroring and RAID-5
volumes
nregionlog=1
nraid5log=1
# by default, limit mirroring log lengths to 32Kbytes
max_regionloglen=32k
# use 64K as the default stripe unit size for regular volumes
stripe_stwid=64k
# use 16K as the default stripe unit size for RAID-5 volumes
raid5_stwid=16k
Discovering the maximum size of a volume
To find out how large a volume you can create within a disk group, use the
following form of the
vxassist command:
# vxassist [-g diskgroup] maxsize layout=layout [attributes]
For example, to discover the maximum size RAID-5 volume with 5 columns and
2 logs that you can create within the disk group, dgrp, enter the following
command:
# vxassist -g dgrp maxsize layout=raid5 nlog=2
You can use storage attributes if you want to restrict the disks that vxassist
uses when creating volumes. See “Creating a volume on specific disks” on
page 244 for more information.
Note: The maximum size of a VxVM volume that you can create is 256TB.
Disk group alignment constraints on volumes
Certain constraints apply to the length of volumes and to the numeric values of
size attributes that apply to volumes. If a volume is created in a disk group that
is compatible with the Cross-platform Data Sharing (CDS) feature, the volume’s
length and the values of volume attributes that define the sizes of objects such
as logs or stripe units, must be an integer multiple of the alignment value of 8
blocks (8 kilobytes). If the disk group is not compatible with the CDS feature, the
volume’s length and attribute size values must be multiples of 1 block
(1kilobyte).