multibos Command

Purpose

Creates, updates, and manages multiple versions of the Base Operating System (BOS) on a rootvg.

Syntax

multibos -s [-l device {-a | -f file | -b file | -x file}] [-e file] [-i file] [-L file] [-p n t N X]

multibos -c -l device {-a | -f file | -b file | -x file} [-p n N X]

multibos -m [-p n X]

multibos -u [-p n X]

multibos -B [-n t X]

multibos -S [-n X]

multibos -R [-p t X]

multibos -s -M file [-nptNX]

Description

The multibos command allows the root level administrator to create multiple instances of AIX® on the same rootvg. The multibos setup operation creates a standby Base Operating System (BOS) that boots from a distinct boot logical volume (BLV). This creates two bootable sets of BOS on a given rootvg. The administrator can boot from either instance of BOS by specifying the respective BLV as an argument to the bootlist command or using system firmware boot operations. Two bootable instances of BOS can be simultaneously maintained. The instance of BOS associated with the booted BLV is referred to as the active BOS. The instance of BOS associated with the BLV that has not been booted is referred to as the standby BOS. Currently, only two instances of BOS are supported per rootvg.

The multibos command allows the administrator to access, install maintenance and technology levels for, update, and customize the standby BOS either during setup or in subsequent customization operations. Installing maintenance and technology updates to the standby BOS does not change system files on the active BOS. This allows for concurrent update of the standby BOS, while the active BOS remains in production.

In addition, the multibos command copies or shares logical volumes and file systems. By default, the BOS file systems (currently /, /usr, /var, and /opt,) and the boot logical volume are copied. The administrator can make copies of additional BOS objects (using the -L flag).

All other file systems and logical volumes are shared between instances of BOS. Separate log device logical volumes (for example, those that are not contained within the file system) are not supported for copy and are shared.

In AIX 5L™ Version 5.3 with the 5300-09 Technology Level, you can populate the standby instance with a later version such as AIX Version 6.1 with the 6100-02 Technology Level. The function is done by creating a mksysb backup of a system at a later version and then using the backup to populate the standby instance. For example, system A is at a level of 5.3.9.0 and system B is at a level of 6.1.2.0. You can create a backup of system B using the mksysb -M command and use the mksysb backup to populate a standby instance of the operating system on system A.

Note:

While the multibos command is running, ensure that system activity is minimal.
Any logical volume or file system attributes that are new to the higher level are note implemented when the standby instance is created because the operating system at a lower level has no knowledge of the attributes.
Do not keep both an AIX 6.1 instance and an AIX 5.3 instance for an extended period. You might not be able to switch between the instances because of incompatibilities. Commit to one of the instances and remove the other.
In addition to the flags mentioned in the syntax section, the -V flag performs the verify operation from the inittab during boot. It is important that you do not modify this entry. The verify operation enables the multibos utility to synchronize changes in logical volumes and file systems between the active and standby instances. This entry also synchronizes the ODM and devices on initial boot after a mksysb restore. Without this operation, both the active and standby instances could become inconsistent with normal file system and logical volume operations.

The file system types (JFS or JFS2) of the mksysb backup need to be the same as that of the system where the multibos command is to be run. For example, if the /usr file system is a JFS2 file system, the /usr file system on the mksysb backup needs to be a JFS2 file system.

A log is stored in the /etc/multibos/logs/op.alog file after you run the multibos command. You can view the log file using the alog -f /etc/multibos/logs/op.alog -o command.

Note: You can create a backup that contains both instances by first mounting the standby instance (using the -m flag), and then creating the backup. However, you can restore the backup onto a disk only by using the alt_disk_mksysb command.

Flags

Item	Description
-a	Specifies the update_all install option. Valid with setup and customization operation.
-B	Build boot image operation. The standby boot image is created and written to the standby BLV using the AIX bosboot command.
-b file	Specifies the install bundle to be installed during the setup or customization operation. The install bundle syntax should follow geninstall conventions.
-c	Performs a customized update of the software in standby BOS.
-e file	Lists active BOS files to be excluded during the setup operation in regular expression syntax.
-f file	Lists fixes (such as APARs) that are to be installed during the setup or customization operation. The syntax of the list follows instfix conventions.
-i file	Specifies optional image.data file to use instead of the default image.data file created from the current rootvg.
-L file	Specifies a file that contains a list of additional logical volumes to include in standby BOS.
-l device	Installs device or directory for software update during the setup or customization operation.
-m	Mounts standby BOS.
-M file	Specifies a file that contains a mksysb image. The mksysb image must have been created using the `mksysb -M` command beginning with AIX 6.1 with 6100-02.
-N	Skips boot image processing. This flag should only be used by experienced administrators that have a good understanding of the AIX boot process.
-n	Does not perform cleanup upon failure. This option is useful to retain multibos data after a failed operation.
-p	Performs a preview of the given operation. Valid with setup, remove, mount, unmount, and customization operations.
-R	Removes all standby BOS objects.
-S	Initiates an interactive shell with chroot access to the standby BOS file systems.
-s	Creates an instance of standby BOS.
-t	Prevents multibos from changing the bootlist.
-u	Unmounts standby BOS.
-x file	Runs the optional customization script before any other customized parameters, such as, update_all (-a), install bundle file (-b), and fix list file (-f). You must use a full pathname for the script.
-X	Allows for automatic file system expansion if space is needed to perform tasks related to multibos. It is recommended that all multibos operations are executed with this flag.

Exit Status

Item	Description
0	All the multibos command operations completed successfully.
>0	An error occurred.

Security

Only the root user can run the multibos command.

Examples

To perform a standby BOS setup operation preview, enter the following command:
```
multibos -Xsp
```
To set up standby BOS, enter the following command:
```
multibos -Xs
```
To set up standby BOS with optional image.data file /tmp/image.data and exclude list /tmp/exclude.list, enter the following command:
```
multibos -Xs -i /tmp/image.data -e /tmp/exclude.list 
```
To set up standby BOS and install additional software listed as bundle file /tmp/bundle and located in the images source /images, enter the following command:
```
multibos -Xs -b /tmp/bundle -l /images
```
To execute a customization operation on standby BOS with the update_all install option, enter the following command:
```
multibos -Xac -l /images
```
To mount all standby BOS file systems, enter the following command:
```
multibos -Xm
```
To perform a standby BOS remove operation preview, enter the following command:
```
multibos -RXp
```
To remove standby BOS, enter the following command:
```
multibos -RX
```
To use an existing mksysb file /backups/mksysb1 to populate the standby instance of rootvg, enter the following command:
```
multibos -M /backups/mksysb1 -sX
```

Restrictions

The multibos command is supported on AIX 5L Version 5.3 with the 5300-03 Recommended Maintenance package and later.
The current rootvg must have enough space for each BOS object copy. BOS object copies are placed on the same disk or disks as the original.
The total number of copied logical volumes cannot exceed 128. The total number of copied logical volumes and shared logical volumes are subject to volume group limits.

Files

Item	Description
/usr/sbin/multibos	Contains the multibos command.
/etc/multibos	Contains multibos data and logs.