mirroring rootvg in order to avoid the impact of the failover time involved in a node failure. In terms of maximizing availability, this technique is just as valid for increasing the availability of a cluster as it is for increasing
The following procedure contains information that will enable you to mirror the root volume group (rootvg), using the advanced functions of the Logical Volume Manager (LVM). It contains the steps required to:
•Mirror all the file systems in rootvg.
•Create an additional boot logical volume (blv).
•Modify the bootlist to contain all boot devices.
You may mirror logical volumes in the rootvg in the same way as any AIX logical volume may be mirrored, either once (two copies), or twice (three copies). The following procedure is designed for mirroring rootvg to a second disk only. Upon completion of these steps, your system will remain available if one of the disks in rootvg fails, and will even automatically boot from an alternate disk drive, if necessary.
If the dump device is mirrored, you may not be able to capture the dump image from a crash or the dump image may be corrupted. The design of LVM prevents mirrored writes of the dump device. Only one of the mirrors will receive the dump image. Depending on the boot sequence and disk availability after a crash, the dump will be in one of the following three states:
1.Not available
2.Available and not corrupted
3.Available and corrupted
State (1) will always be a possibility. If the user prefers to prevent the risk of encountering State (3), then the user must create a
In AIX 4.2.1, two new LVM commands were introduced: mirrorvg and unmirrorvg. These two commands where introduced to simplify mirroring or unmirroring of the entire contents of a volume group. The commands will detect if the entity to be mirrored or unmirrored is rootvg, and will give slightly different completion messages based on the type of volume group.The mirrorvg command does the equivalent of Procedure steps (2), (3), and (4).
The mirrorvg command takes dump devices and paging devices into account. If the dump devices are also the paging device, the logical volume will be
