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
Note that because four subdisks are specified, but the number of columns is not specified, the vxmake command assumes a four-column RAID-5 plex and places one subdisk in each column. Striped plexes are created using the same method except that the layout is specified as stripe. If the subdisks are to be created and added later, use the following command to create the plex:
# vxmake -g mydg plex raidplex layout=raid5 ncolumn=4 stwidth=32
If each column in a RAID-5 plex is to be created from multiple subdisks which may span several physical disks, you can specify to which column each subdisk should be added. For example, to create a three-column RAID-5 plex using six subdisks, use the following form of the vxmake command:
# vxmake -g mydg plex raidplex layout=raid5 stwidth=32 \ sd=mydg00-00:0,mydg01-00:1,mydg02-00:2,mydg03-00:0, \ mydg04-00:1,mydg05-00:2
This command stacks subdisks mydg00-00 and mydg03-00 consecutively in column 0, subdisks mydg01-00 and mydg04-00 consecutively in column 1, and subdisks mydg02-00 and mydg05-00 in column 2. Offsets can also be specified to create sparse RAID-5 plexes, as for striped plexes.
# vxmake -g mydg plex raidlog1 sd=mydg06-00 # vxmake -g mydg plex raidlog2 sd=mydg07-00
# vxmake -g mydg -Uraid5 vol raidvol \ plex=raidplex,raidlog1,raidlog2
Each RAID-5 volume has one RAID-5 plex where the data and parity are stored. Any other plexes associated with the volume are used as RAID-5 log plexes to log information about data and parity being written to the volume.