236Creating volumes

Types of volume layouts

Types of volume layouts

VxVM allows you to create volumes with the following layout types:

Concatenated

A volume whose subdisks are arranged both sequentially and

 

contiguously within a plex. Concatenation allows a volume to be

 

created from multiple regions of one or more disks if there is not

 

enough space for an entire volume on a single region of a disk. For

 

more information, see “Concatenation and spanning” on page 35.

Striped

A volume with data spread evenly across multiple disks. Stripes are

 

equal-sized fragments that are allocated alternately and evenly to the

 

subdisks of a single plex. There must be at least two subdisks in a

 

striped plex, each of which must exist on a different disk. Throughput

 

increases with the number of disks across which a plex is striped.

 

Striping helps to balance I/O load in cases where high traffic areas

 

exist on certain subdisks. For more information, see “Striping (RAID-

 

0)” on page 38.

Mirrored

A volume with multiple data plexes that duplicate the information

 

contained in a volume. Although a volume can have a single data plex,

 

at least two are required for true mirroring to provide redundancy of

 

data. For the redundancy to be useful, each of these data plexes

 

should contain disk space from different disks. For more information,

 

see “Mirroring (RAID-1)” on page 42.

RAID-5

A volume that uses striping to spread data and parity evenly across

 

multiple disks in an array. Each stripe contains a parity stripe unit

 

and data stripe units. Parity can be used to reconstruct data if one of

 

the disks fails. In comparison to the performance of striped volumes,

 

write throughput of RAID-5 volumes decreases since parity

 

information needs to be updated each time data is modified. However,

 

in comparison to mirroring, the use of parity to implement data

 

redundancy reduces the amount of space required. For more

 

information, see “RAID-5 (striping with parity)” on page 45.

Mirrored-stripe

A volume that is configured as a striped plex and another plex that

 

mirrors the striped one. This requires at least two disks for striping

 

and one or more other disks for mirroring (depending on whether the

 

plex is simple or striped). The advantages of this layout are increased

 

performance by spreading data across multiple disks and redundancy

 

of data. “Striping plus mirroring (mirrored-stripe or RAID-0+1)” on

 

page 42.