AIX Version 4.3 Differences Guide

Note
Although the chlvcopy command can mark on-line backup copies on logical
volumes that are open (including logical volumes containing mounted file
systems), this is not recommended unless the application is at a known state at
the time the copy is marked as a backup. The backup copy is internally
consistent at the time the chlvcopy command is run, but consistency is lost
between the logical volume and the backup copy if the logical volume is
accessed by multiple processes simultaneously, and the application is not at a
known state. When marking an open logical volume, data may be lost or
corrupted. Logical volumes should be closed before marking on-line backup
copies in order to avoid a potential corruption window.
The -P,-l, and -w are new options for AIX 4.3.2.
If the persistence flag -P is not set to prevent the loss of backup data, the volume
group should be set to not automatically varyon, and the -n flag should be used
with varyonvg to prevent stale partitions from being resynced. If the persistence
flag -P is set, the following applies: in the event of a crash while an on-line
backup copy exists (or multiples exist), the existence of copies is retained when
the system is rebooted.
Use the -l or -P flag to prevent the volume group from being unstable on prior
releases of AIX.
Table 21 lists the new options of chlvcopy command in AIX 4.3.2.
Table 21. New Options for chlvcopy Command in AIX 4.3
Flag
Description
-P Maintains information about the existence of an online backup copy across a
reboot and also allows other nodes (in a concurrent mode environment) to be
aware of the existence of the online backup(s).
-l New name of the backup logical volume. If one is not provided, one will be
created by the system.
-w Allow backup copy to be writable (default is to create the backup copy as
READ ONLY)
To create an on-line backup, perform the following steps:
1. Unmount the filesystem from the mirrored LV
2. Execute chlvcopy -b -c -l
3. Remount the original filesystem
4. Execute mount -o ro /dev/ /
5. Backup the backupfs
6. Execute unmount /
7. Execute chlvcopy -B original_lvname
In general, use chlvcopy the same as you would splitlvcopy.
94 AIX Version 4.3 Differences Guide