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If a disk is unavailable when the system is running, any mirrors of volumes that reside on that disk become stale. This means that the data on that disk is inconsistent relative to the other mirrors of that volume. During the boot process, the system accesses only one copy of the root volume (the copy on the boot disk) until a complete configuration for this volume can be obtained.
If it turns out that the plex of this volume that was used for booting is stale, the system must be rebooted from an alternate boot disk that contains non-stale plexes. This problem can occur, for example, if the system was booted from one of the disks made bootable by VxVM with the original boot disk turned off. The system boots normally, but the plexes that reside on the unpowered disk are stale. If the system reboots from the original boot disk with the disk turned back on, the system boots using that stale plex.
Another possible problem can occur if errors in the Veritas Volume Manager headers on the boot disk prevent VxVM from properly identifying the disk. In this case, VxVM does not know the name of that disk. This is a problem because plexes are associated with disk names, so any plexes on the unidentified disk are unusable.
A problem can also occur if the root disk has a failure that affects the root volume plex. At the next boot attempt, the system still expects to use the failed root plex for booting. If the root disk was mirrored at the time of the failure, an alternate root disk (with a valid root plex) can be specified for booting.
If any of these situations occur, the configuration daemon, vxconfigd, notes it when it is configuring the system as part of the init processing of the boot sequence. vxconfigd displays a message describing the error and what can be done about it, and then halts the system. For example, if the plex rootvol-01 of the root volume rootvol on disk rootdisk is stale, vxconfigd may display this message:
VxVM vxconfigd ERROR V-5-1-1049: System boot disk does not have a valid root plex
Please boot from one of the following disks:
vxvm:vxconfigd: Error: System startup failed
This informs the administrator that the alternate boot disk named disk01 contains a usable copy of the root plex and should be used for booting. When this message is displayed, reboot the system from the alternate boot disk.
See "Booting from an alternate boot disks" on page 38.
Once the system has booted, the exact problem needs to be determined. If the plexes on the boot disk were simply stale, they are caught up automatically as the system comes up. If, on the other hand, there was a problem with the private area on the disk or the disk failed, you need to re-add or replace the disk.
If the plexes on the boot disk are unavailable, you should receive mail from Veritas Volume Manager utilities describing the problem. Another way to determine the problem is by listing the disks with the vxdisk utility. If the problem is a failure in the private area of root disk (such as due to media failures or accidentally overwriting the Veritas Volume Manager private region on the disk), vxdisk list shows a display such as this:
- - rootdisk bootdg failed was: c0t3d0s2
c0t1d0s2 sliced disk01 bootdg ONLINE