Working With Configuration Files

Solaris Volume Manager configuration files contain basic Solaris Volume Manager information, as well as most of the data that is necessary to reconstruct a configuration. The following procedures illustrate how to work with these files.

How to Create Configuration Files

Once you have defined all appropriate parameters for the Solaris Volume Manager environment, use the metastat -p command to create the /etc/lvm/md.tab file.
```
# metastat -p > /etc/lvm/md.tab
```
This file contains all parameters for use by the metainit command and metahs command. Use this file if you need to set up several similar environments or if you need to recreate the configuration after a system failure.
For more information about the md.tab file, see Overview of the md.tab File and the md.tab(4) man page.

How to Initialize Solaris Volume Manager From a Configuration File

Caution - Use this procedure in the following circumstances:

If you have experienced a complete loss of your Solaris Volume Manager configuration
If you have no configuration yet, and you want to create a configuration from a saved configuration file

On occasion, your system loses the information maintained in the state database. For example, this loss might occur if the system was rebooted after all of the state database replicas were deleted. As long as no volumes were created after the state database was lost, you can use the md.cf or md.tab files to recover your Solaris Volume Manager configuration.

Note - The md.cf file does not maintain information on active hot spares. Thus, if hot spares were in use when the Solaris Volume Manager configuration was lost, those volumes that were using active hot spares are likely corrupted.

For more information about these files, see the md.cf(4) and the md.tab(4) man pages.

Create state database replicas.
See Creating State Database Replicas for more information.
Create or update the /etc/lvm/md.tab file.
- If you are attempting to recover the last known Solaris Volume Manager configuration, copy the md.cf file into the /etc/lvm/md.tab file.
- If you are creating a new Solaris Volume Manager configuration based on a copy of the md.tab file that have you preserved, copy the preserved file into the /etc/lvm/md.tab file.
Edit the “new” /etc/lvm/md.tab file and do the following:
- If you are creating a new configuration or recovering a configuration after a crash, configure the mirrors as one-way mirrors. For example:
```
d80 -m d81 1
d81 1 1 c1t6d0s3
```
  If the submirrors of a mirror are not the same size, be sure to use the smallest submirror for this one-way mirror. Otherwise, data could be lost.
- If you are recovering an existing configuration and Solaris Volume Manager was cleanly stopped, leave the mirror configuration as multi-way mirrors. For example:
```
d70 -m d71 d72 1
d71 1 1 c1t6d0s2
d72 1 1 c1t5d0s0
```
- Specify RAID-5 volumes with the -k option, to prevent reinitialization of the device. For example:
```
d45 -r c1t3d0s5 c1t3d0s3 c1t3d0s4 -k -i 32b
```
  See the metainit(1M) man page for more information.
Check the syntax of the /etc/lvm/md.tab file entries without committing changes by using one of the following forms of the metainit command:
```
# metainit -n md.tab-entry
```
```
# metainit -n -a
```
The metainit command does not maintain a hypothetical state of the devices that might have been created while running with the -n, so creating volumes that rely on other, nonexistent volumes will result in errors with the -n even though the command may succeed without the -n option.
-n

Specifies not to actually create the devices. Use this option to verify that the results are as you expected.

md.tab-entry

Specifies the name of the component to initialize.

-a

Specifies to check all components.
If no problems were apparent from the previous step, recreate the volumes and hot spare pools from the md.tab file:
```
# metainit -a
```
-a

Specifies to activate the entries in the /etc/lvm/md.tab file.
As needed, make the one-way mirrors into multi-way mirrors by using the metattach command.
```
# mettach mirror submirror
```
Validate the data on the volumes to confirm that the configuration has been reconstructed accurately.
```
# metastat
```