Recreating LVM Structures using Sysback Version 4

About this document
Related documentation
Creating a vginfo file
Recreate volume group, logical volume and/or filesystem
Partition mapping
Hints and tips

About this document

This document describes how to create a Sysback vginfo file containing Logical Volume Manager (LVM) structure information with a procedure that does not back up any data, and recreating the structure.

This document applies to AIX versions 4.1 and above and Sysback versions 4.1 and above.

Creating a TOC file

This is a two step process. Make a text vginfo file with the mkvginfo command, then convert it to a TOC (table of contents) file usable by the remakevg command.

On the source system, enter the following commands:

For Volume Group Information (Includes Logical Volume and Filesystem):

     mkvginfo -f -o /tmp/vginfo.txt -v <list of Volume Groups separated by spaces>
     echo vginfo | sbwrite -T /tmp/vginfo.txt /tmp/TOC

For Logical Volume and/or Filesystem Information Only:

     mkvginfo -f -o /tmp/vginfo.txt -l <list of Logical Volumes separated by spaces>
     echo vginfo | sbwrite -T /tmp/vginfo.txt /tmp/TOC

The new TOC file that is created in the /tmp directory is what will be used to recreate the structures.

NOTE: To preserve partition mapping, see Partition mapping below.

Recreate Volume Group, Logical Volume, and/or Filesystem

Copy the new TOC file to the target system into the /tmp directory.

For Volume Group(s), including Logical Volumes and/or Filesystems:

     remakevg -v -f /tmp/TOC -E <list of Volume Groups separated by spaces>

For Logical Volumes and/or Filesystem only:

     remakevg -l -f /tmp/TOC -E <list of Logical Volumes separated by spaces>

For example, to recreate the logical volumes lv00 and lv01 from the TOC file located in /tmp, enter:

        remakevg -l -f /tmp/TOC -E lv00 lv01

To recreate the volume groups testvg and datavg and all of their accompanying logical volumes and filesystems from the TOC file located in /tmp:

     remakevg -v -f /tmp/TOC -E testvg datavg

The -E flag in the commands above indicates that the user-interface menus should be displayed to allow LVM information to be changed before the structure is recreated. This process is documented in the Sysback manual section titled "Changing the Volume Group, logical volume and Filesystem Attributes".

Partition mapping

Sysback has the option ( -M flag on the mkvginfo command) to preserve partition mapping in the vginfo file. Note however, that when recreating the volume group, logical volume, and/or filesystem, Sysback checks the Physical Volume ID (PVID) of the hdisks in the system. If those do not match what is in the vginfo file, the partition mapping is ignored.

At that point, a volume group's logical volumes are created in alphabetical order first, then the filesystems are created in alphabetical order. All of the logical volumes are created before any filesystems are created. Sysback will attempt to create the logical volumes with their specified write policy, but on a first come, first serve basis.

Hints and tips

Filesystem mount points created through these procedures will have default ownership/permissions of:

	drwxr-sr-x   3 sys      sys

Sysback does not set the ownership and permissions until the data is restored. Since no data is being restored with this document, the permissions will need to be set manually after the filesystems have been created.

NOTE: The following procedure is not supported.

To preserve partition mapping to a different PVID:
1. Make sure the new hdisk is the same size as the original.
2. Create the vginfo file with the mkvginfo command above.
3. Find the corresponding PVID of the source disk, and of the target disk. Enter the following command:
```
     lspv
```
  Look for the following fields from the output of the lpsv command:
```
     hdisk#    <PVID>   <Volume Group>
```
4. Edit the vginfo file. Replace every instance of the original PVID with the target PVID. If the AIX location codes are different, replace the AIX location code as well.
5. Create the .TOC file as above.
6. Recreate the volume group, logical volume, and/or filesystem as above.
Copying the vginfo file from an existing Sysback tape backup:

If the block size that the backup was made with is already known, proceed to step 6.
1. chdev -l rmt# -a block_size=512
2. tctl -f /dev/rmt# rewind
3. cd /
4. restore -s4 -xvqf /dev/rmt#.1 ./tmp/...blksz
5. chdev -l rmt# -a block_size=`cat /tmp/...blksz`
6. tctl -f /dev/rmt# rewind
7. tctl -f /dev/rmt#.1 fsf 4
8. sbread -T rmt# > /tmp/vginfo.txt
Using the TOC file from a disk image backup:

In the directory that the backup was made to, there is a file named *.TOC. Specify that file to use with the remakevg command that was discussed earlier in this document.

[ Doc Ref: 95807393813270 Publish Date: Spt. 19, 2000 4FAX Ref: 8667 ]