Understanding data management

Volume structure

Unmirrored and mirrored volumes

A volume can be unmirrored or mirrored. An unmirrored volume has one plex; a mirrored volume has two plexes that are updated simultaneously. A plex contains all of the data in a volume. Therefore, a mirrored volume contains two copies of the data. This chapter discusses unmirrored volumes unless mirroring is explicitly stated.

You must have a SyncMirror^TM license to use mirror capabilities. See the Data Protection Guide for more information about mirrored volumes.

What a plex is

A plex is a physical copy of a file system and consists of one or more RAID groups. The following diagram illustrates a plex.

How volume plexes and RAID groups are named

The syntax used by Data ONTAP to name plexes is as follows:

vol-name/plexplexid

vol-name is the name of the volume.

plexid is the number of the plex and is assigned by Data ONTAP.

The syntax used by Data ONTAP to name RAID groups is as follows:

vol-name/plexplexid/rgraid-group-id

raid-group-id is the number of the RAID group.

Examples

vol0 specifies all the plexes and RAID groups of volume vol0.

vol0/plex1 specifies all the RAID groups of plex 1 of volume vol0.

vol0/plex1/rg2 specifies RAID group 2 of plex 1 of volume vol0.