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HP-UX System Administration Tasks: HP 9000 > Chapter 7 Mirroring Data Using LVM
Mirroring Tasks that Must Be Performed Using HP-UX Commands |
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Certain mirroring tasks cannot be performed by SAM. For the tasks described below, you will have to use the appropriate HP-UX commands. Suppose you have a mirrored logical volume (/dev/vg01/lvol4). The mirror copy is on a disk you want to remove from the system (/dev/dsk/c7t0d0). There is room on another disk (/dev/dsk/c5t0d0) in the same volume group for the mirror copy. You can move a logical volume's mirror copy from one disk to another by using pvmove(1M). To move the copy, you issue the following command:
At times, the data in your mirrored copy or copies of a logical volume can become out of sync, or "stale". For example, this might happen if LVM cannot access a disk as a result of disk power failure. Under such circumstances, in order for each mirrored copy to re-establish identical data, synchronization must occur. Usually, synchronization occurs automatically, although there are times when it must be done manually. If you activate a volume group that is not currently active, either automatically at boot time or later with the vgchange command, LVM automatically synchronizes the mirrored copies of all logical volumes, replacing data in physical extents marked as stale with data from non-stale extents. Otherwise, no automatic synchronization occurs and manual synchronization is necessary. LVM also automatically synchronizes mirrored data in the following cases:
If you look at the status of a logical volume using lvdisplay -v, you can see if the logical volume contains any stale data. You can then identify which disk contains the stale physical extents. You manually synchronize the data in one or more logical volumes using either the lvsync command or all logical volumes in one or more volume groups using the the vgsync command. See lvdisplay(1M), vgsync(1M) , and lvsync(1M) for more information. In the event you need to replace a non-functional mirrored disk, you should perform the following steps to ensure that the data on the replacement disk are both synchronized and valid:
Consult the HP-UX Reference for additional information on any of the above commands. |
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