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Augmented Failover, Failback, and Role Reversal Procedures
Augmented Failover, Failback, and Role Reversal Procedures
Throughout the failover, failback, and role reversal procedures in the March 2004 release of
the HP StorageWorks Data Replication Manager HSG80 ACS Version 8.7P Failover/Failback
Procedures Guide, you are instructed to remove host access at certain points in the procedures,
and to enable host access at other points. Because you are using VERITAS Volume Manager to
manage your storage units, you need to be aware of the special handling required of the
volumes before and after you perform the failover, failback, and role reversal procedures. You
will need to perform several extra steps to import, deport, mount, unmount, force import, or
check volumes.
Before removing host access to the storage units, as you would do prior to performing a
planned failover or role reversal, you will need to remove access from VERITAS Volume
Manager. To cleanly remove access from a host that has access to disks under VERITAS
Volume Manager control, you will first unmount all of the volumes under a disk group, then
deport the disk group. This will enable you to disable the host access without unintended
consequences.
Be aware that if you deport a disk group, and there is an entry in the /etc/vfstab file to mount a
volume from that disk group upon host boot, then the host will give an error during the boot
sequence because it cannot find the volume. To prevent this from occurring, comment out the
line for that particular volume in the /etc/vfstab file.
After you have enabled host access from the controllers, as you would do at the target site after
a planned failover or role reversal failover procedure, or at the initiator site after a failback or
role reversal failback procedure, you must then place the volumes back under the control of
VERITAS Volume Manager. To give VERITAS Volume Manager access to the volume, you
will need to first import the disk group that the volume was under, and then mount the volume.
The I/O operations at the site can then be restarted.
The procedures for an unplanned failover are different from those for a planned failover. When
an unplanned failover occurs, and the volume was not deported from the initiator, the volume
still has the initiator host label on it. To allow target access to the volume, you will need to
import the volume by performing a forced import and using the clear host ID option. After you
have successfully forced the import of the volume, you will need to check the volume’s file
system with the fsck utility. When the fsck function has completed, you can then start and
mount the volume, and begin I/O processes.
Definitions of Volume Manager Terms
Import—Bring a deported disk group and its Volume Manager objects into a system from
another system.
Deport—Move a disk group and its Volume Manager objects out of the current system. The
group and its disks can then be used in another system.
Mount—Attach a file system to the file system hierarchy at the mount point, which is the
pathname of the directory (gains access to the read and write functions of a hard drive).
Unmount—Unattach a currently mounted file system (removes access to the read and write
functions of a hard drive).
Force import—Bring a disk group and its Volume Manager objects into a system without
having the diskgroup first deported from the previous system.
Check volumes (fsck)—Check and repair file systems. The fcsk function audits and
interactively repairs inconsistent file system conditions.
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Data Replication Manager for Sun Solaris 7 and 8 with VERITAS Volume Manager 3.xApplication Notes
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