HP 3000 Manuals HP 3000 Manuals
Volume Management Terms
This section describes volumes, volume sets, and volume classes in more
detail.
Volumes
A volume is a disk pack. A disk pack can be removable or nonremovable.
The system recognizes a volume in a particular volume state. The volume
state determines whether the volume is available or not. Volume states
are described in chapter 3 of this manual.
Volume Sets
There are two types of volume sets, the system volume set and optional
nonsystem volume sets. The system volume set is created when the
operating system is installed and is always mounted when the system is
operating. You can add extra volumes to the system volume set while the
system is running. The system volume set contains two types of storage
space, permanent and transient. Permanent space is used for files
(permanent and temporary), label tables, and free space maps. Transient
space is used for temporary data structures (stacks, heaps, and operating
system data structures).
You create nonsystem volume sets when you want to restrict data for data
accessibility, decrease the impact to system downtime (if a non-system
volume is bad), or if you have to re-install the system. You can create
and add extra volumes to nonsystem volume sets while the system is
running. Nonsystem volume sets can be mounted on the system as needed
and they contain only permanent space. If nonsystem volume sets are not
defined on the system, all volumes will be part of the system volume set.
Table 2-1 lists the differences between the system volume set and
nonsystem volume sets.
Table 2-1. Differences between System and Nonsystem Volume Sets
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| | |
| System Volume Set | Nonsystem Volume Sets |
| | |
-------------------------------------------------------------
| | |
| Maximum one system | Up to 32 nonsystem volume sets |
| volume set per system. | per system. |
| | |
-------------------------------------------------------------
| | |
| Named | Can be any name up to 32 |
| MPEXL_SYSTEM_VOLUME_SET. | characters long. |
| | |
-------------------------------------------------------------
| | |
| Always mounted when | Can be removed (dismounted) |
| system is running. | while system running, if not |
| | needed. |
| | |
-------------------------------------------------------------
| | |
| Contains permanent and | Allows permanent storage only. |
| transient storage. | (Disk space used for files, |
| (Disk space used for | label tables, and free space |
| temporary structures.) | maps.) |
| | |
-------------------------------------------------------------
| | |
| User data and system | User data can be partitioned |
| data reside on same | onto separate disks. |
| system disks. | |
| | |
-------------------------------------------------------------
| | |
| Master contains system | Requires master to be present |
| image and | to use the set. |
| configuration(s). | |
| Requires master to be | |
| present to boot the | |
| system. | |
| | |
-------------------------------------------------------------
| | |
| Additional members can | Additional members can be |
| be added using the | added using the VOLUTIL |
| VOLUTIL utility while | utility while the system is |
| the system is operating. | operating. |
| | |
-------------------------------------------------------------
Nonsystem volume sets are also called user or mountable volume sets since
they are not required for the system to run. You can remove (dismount)
some or all of the volumes in a nonsystem volume set.
Types of Volumes
A volume set consists of two types of volumes, a master volume and
optional member volumes. A volume set is created when the master volume
is created. The master volume is the controlling volume of each set and
must be present in order to access the set. The master contains the
Volume Set Information Table (VSIT), the free space map, the file label
table, and the root node of the accounting directory for the set. The
VSIT is a table that contains information about all of the volumes and
classes in the set. A member volume contains a volume label that
identifies its volume set, a free space map, and a file label table.
Master Volumes.
Table 2-2 lists the information contained on the master volume of a
volume set.
Table 2-2. Master Volume Information
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| | |
| Information | Description |
| | |
-------------------------------------------------------------
| | |
| volume label | Name of the master volume. |
| | |
-------------------------------------------------------------
| | |
| file label table | File labels for the files |
| | residing on the volume set. |
| | |
-------------------------------------------------------------
| | |
| free space map | Map of allocated and available |
| | disk sectors on the volume |
| | set. |
| | |
-------------------------------------------------------------
| | |
| directory root | Contains the directory of the |
| | volume set. |
| | |
-------------------------------------------------------------
| | |
| volume set's information | Defines the volume set's |
| table (VSIT) | configuration including volume |
| | set's name, names of the |
| | volumes and classes in the |
| | set, and the volumes in each |
| | class. |
| | |
-------------------------------------------------------------
| | |
| Files | User data. |
| | |
-------------------------------------------------------------
The volume master of a nonsystem volume set is the only volume needed to
define a volume set. When a master volume is mounted, the volume set is
considered mounted. The master volume must be mounted before any file
access can be made to other members of the volume set.
The master volume is created when you create a nonsystem volume set. It
contains information about the set, including a root directory which
enables the system to recognize the volume set.
The system master volume is initialized as LDEV 1. After the system is
rebooted, additional volumes may be added online to the system volume set
using the VOLUTIL utility described in chapter 3 of this manual. The
master volume for the system volume set contains all the system files and
system configuration information. It must be mounted for the system to
boot or run.
![[]](../../pic3k/M013418/FFN93c50.gif)
Figure 2-4. A Master Volume
NOTE The master volume of a nonsystem volume set must be mounted for the
system to recognize the volume set.
The master volume of the system volume set must be mounted to boot
the system.
Member Volumes.
Member volumes can be added online after the volume set is created. They
contain the information described in Table 2-3 .
Table 2-3. Member Volume Information
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| | |
| Information | Description |
| | |
-------------------------------------------------------------
| | |
| Volume Label | Name of the member volume. |
| | |
-------------------------------------------------------------
| | |
| File Label Table | Contains the file labels for |
| | the files residing on the |
| | volume set. |
| | |
-------------------------------------------------------------
| | |
| Free Space Map | Map of allocated and available |
| | disk sectors on the volume |
| | set. |
| | |
-------------------------------------------------------------
| | |
| Files | User data. |
| | |
-------------------------------------------------------------
Member volumes can belong to only one volume set since the root directory
for their file information is contained on the master volume of the set.
![[]](../../pic3k/M013418/FFN103c50.gif)
Figure 2-5. A Member Volume
Volume Classes.
A volume class is a subset of the volumes within one volume set. Volume
classes are useful in restricting data to particular volumes in a volume
set. Only the master volume and those particular volumes are needed to
run applications. When data is restricted to a volume class, this limits
the chance of losing data if a particular volume fails. Then problems on
volumes outside that class, except the master volume, do not affect that
data.
If resources are limited, more volumes can be defined in a set than there
are physical drives to mount them. In this case, the volumes can be
grouped into classes according to the types of information they contain.
The volumes within a specific class can then be mounted as the data is
needed.
Additionally, volume classes can be used to keep application programs on
one drive and data on another, or to allow data to be mounted at
different times.
NOTE When you create a new volume set, unless you specify another class,
volume management assigns all volumes in the set to the default
volume class, DISC.