VERITAS Volume Manager 3.1 Administrator's Guide

Recovery
RAID-5 Volume Layout
Chapter 8364
RAID-5 Volume Layout
NOTE You may need an additional license to use this feature.
A RAID-5 volume consists of one or more plexes, each of which consists of
one or more subdisks. Unlike mirrored volumes, not all plexes in a
RAID-5 volume serve to keep a mirror copy of the volume data. A RAID-5
volume can have two types of plexes, as follows:
the RAID-5 plex is used to keep both data and parity for the volume
the log plexes keep logs of data written to the volume for faster and
more efficient recovery
RAID-5 Plexes
RAID-5 volumes keep both the data and parity information in a single
RAID-5 plex. A RAID-5 plex consists of subdisks arranged in columns,
similar to the striping model. See the following display:
PL NAME VOLUME KSTATE STATE LENGTH LAYOUT NCOL/WID MODE
SD NAME PLEX DISK DISKOFFS LENGTH [COL/]OFF DEVICE MODE
pl r5vol-01 rvol ENABLED ACTIVE 20480 RAID 3/16 RW
sd disk00-00 rvol-01 disk00 010240 0/0 c1t4d1 ENA
sd disk01-00 rvol-01 disk01 010240 1/0 c1t2d1 ENA
sd disk02-00 rvol-01 disk02 010240 2/0 c1t3d1 ENA
NOTE Your system may use a device name that differs from the examples. For
more information on device names, see “Disk Devices”.
The plex line shows that the plex layout is RAID and that it has three
columns and a stripe unit size of 16 sectors. Each subdisk line shows the
column in the plex and offset in the column in which it is located.
RAID-5 Logs
Each RAID-5 volume has one RAID-5 plex where the data and parity are