A plex consists of one or more subdisks located on one or more physical disks. * A plex is a structured or ordered collection of subdisks that represents one copy of the data in a volume. If required, this default can be changed, using the vol_subdisk_num tunable parameter. * There is no theoretical limit to number of subdisks that can be attached to a single plex, but it has been limited to a default value of 4096. * The maximum number of partitions to a disk is eight.
#Veritas volume manager user guide free
You can use free space to create new subdisks.Ī subdisk is similar to a partition but with following differences : * volume manager disk space that is not reserved or that is not part of a subdisk is free space. * A volume manager disk can contain multiple subdisks but subdisks cannot overlap or share the same portions of a volume manager disk. * A subdisk is defined by an offset and a length in sectors on a volume manager disk. * A subdisk is a subsection of a disk’s public region and is the smallest unit of storage in Volume Manager. The physical address of c#t#d# becomes known as the disk access record. * Once a volume manager disk is assigned a disk media name, the disk is no longer referred to by its physical address of c#t#d#. * A volume manager disk is given a disk media name when it is added to a disk group which can be default or unique user defined. Each volume manager disk corresponds to one physical disk. * A Volume Manager disks are created from the public region of a physical disk that is under Volume Manager control. The public region is the disk space available for volume space and the private region stores the configuration information.
* Adding physical disks to the volume manager results in creation of public and private region in the disk by the volume manager. In two hosts and a shared storage situation one host can take over the ownership of the disk groups and drives in case other host fails. * Disk groups enable high availability as these can be shared by two or more hosts but can be accessed by only one host at a time.
all the operations on a particular disk group remains confined to that particular group. * Volume Manager objects cannot span disk groups i.e.
All the configuration changes made to a disk group are applied to the disks in that disk group only. * A disk group is a collection of volume manager disks grouped together to hold the data. While device name is system dependent based on controller and disk id the disk name is user defined. įor example device name c2t3d0s2 represents controller number 2, target id 3, disk group 0 and slice 2 and disk01 may be its disk name. Disk name is the common name given to the device name as an easy to remember name. The device name specifies controller, target id and slice of the disk. Volume Manager Configuration ( options menu)Ģ.8 Enable access to (import) a disk groupĢ.9 Remove access to (deport) a disk groupĢ.12 Mark a disk as a spare for a disk groupĭisks are referred in volume manager by two terms – device name and disk name. ġ.7 Volume Manger Objects & their RelationshipĢ.
The following article describes the volume manager objects and configuration of these objects using a text menu based utility called vxdiskadm. Dynamic reconfiguration of disk storage in an online system state. Provides fail over features by providing transferable disk group ownership between systems.Ĥ. Provides high availability storage solutions through RAID ,Mirroring of disks. This overcomes the physical limit of the disk. Allows creation of logical volumes spanning over multiple disks. The main features of volume manager are followingġ. Veritas Volume Manager is used to manage disk storage spread over an array of disks.