Example 1---Decision Support Using the Traditional Snapshot Feature and the vxibc Utility

1. On the Secondary, register the application name dss_app and get ready to receive the IBC message. The command to break-off the snapshot plex when the IBC is received is specified with the vxibc regrecv command, as follows:
     # vxibc -g hrdg regrecv dss_app hr_rvg vxrvg snapshot hr_rvg
2. On the Primary, put the application that is using the Primary data volumes hr_dv01 and hr_dv02 into a consistent state.

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     Note    Putting the application in a consistent state involves flushing all the buffers and pending transactions. For example, the file system can be brought into a consistent state by synchronizing the volumes using the VxFS specific sync command. In Oracle, the application can be brought into a consistent state by putting it in a hot-backup mode.

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3. On the Primary, register the application name dss_app and send the IBC message using the following command:
     # vxibc -g hrdg regsend dss_app hr_rvg

   When the Secondary receives the IBC message, replication is frozen and no more data is written to the secondary data volumes. The vxrvg snapshot command specified in step 1 then breaks-off the snapshot plexes from the Secondary data volumes, and replication starts again. When the vxibc commands complete on both the hosts, the application name is unregistered.

4. On the Primary host, resume the application if it was suspended in step 2.

   If the RLINK is asynchronous and behind there may be a delay between the vxibc regsend and vxrvg snapshot command. During this delay, the application is running.

5. On the Secondary, use the snapshot data volumes SNAP-hr_dv01 and SNAP-hr_dv02 for running the DSS application, that is, for off-host processing.
6. When the application completes, reattach the snapshot plexes to the data volumes using the following command:
     # vxrvg -g hrdg snapback hr_rvg

   The reattach destroys the SNAP volumes and reattaches the snapshot plexes to their original volumes. If you have enabled FR on these volumes, only the blocks that were changed by the off-host processing application are resynchronized.

Example 2---Backing Up Using the Snapshot Feature and the vxibc Utility

1. Perform step 1 to step 4 of Example 1---Decision Support Using the Traditional Snapshot Feature and the vxibc Utility.
2. On the Secondary, copy the snapshot to tapes using a backup utility or the UNIX command dd. Use the dd command as follows:
     # dd if=/dev/vx/rdsk/hrdg/SNAP-hr_dv01 of=/dev/rmt/0
     # dd if=/dev/vx/rdsk/hrdg/SNAP-hr_dv02 of=/dev/rmt/0
3. Reattach the snapshot plexes to the original volumes:
     # vxrvg -g hrdg snapback hr_rvg

Example 3---Trial Failover Using the Snapshot Feature

Because the goal is to simulate a crash on the Primary, do not use IBC Messaging for trial failover.

1. Pause the RLINK either on the Primary or the Secondary to maintain consistency.
   To pause the RLINK on the Primary, type:
     # vxrlink -g hrdg pause rlk_london_hr_rvg

   To pause the RLINK on the Secondary, type:

   
     # vxrlink -g hrdg pause rlk_seattle_hr_rvg
2. When the RLINK is paused, take snapshots of all the data volumes in the RVG:
     # vxrvg -g hrdg -P trial snapshot hr_rvg

   where trial is the prefix for the snapshot plexes for all data volumes. Snapshot data volumes with names trial-hr_dv01 and trial-hr_dv02 are created.

3. When the snapshots are complete, resume the RLINK by typing:
     # vxrlink -g hrdg resume rlink_name

   where rlink_name is the name of the paused RLINK.

4. Start the application using the data volumes trial-hr_dv01 and trial-hr_dv02 that you have snapped off.
5. Use the recovery function of the application to recover it, and then run the application. For example to recover a vxfs file system, use fsck.
     # fsck -F vxfs /dev/vx/rdsk/hrdg/trial-hr_dv01
     # fsck -F vxfs /dev/vx/rdsk/hrdg/trial-hr_dv02
6. When the test is complete, shut down the application. For a file system, unmount the file system.
7. Reattach the snapshot plexes to the original data volumes.
     # vxrvg -g hrdg -P trial snapback hr_rvg

   The -P option to the vxrvg snapback command reattaches to the original volume the plexes with the prefix specified when taking the snapshot.

Example 4---Decision Support Using the Instant Full Snapshot Feature and the vxibc Utility

1. On the Secondary, prepare the volumes for which you want to create instant snapshots using the command:
   # vxsnap -g hrdg prepare hr_dv01 
   # vxsnap -g hrdg prepare hr_dv02

   This operation needs to be performed only for the first time you perform the snapshot operation.

2. On the Secondary, create snapshot volumes of the same size as the original volumes and with an appropriate prefix:
   # vxassist -g hrdg make dss-hr_dv01 volume_length 
   # vxassist -g hrdg make dss-hr_dv02 volume_length

   where volume_length is the length of the original volumes.

3. On the Secondary, prepare the snapshot volumes for which you want to create instant snapshots using the command:
   # vxsnap -g hrdg prepare dss-hr_dv01 
   # vxsnap -g hrdg prepare dss-hr_dv02
4. On the Secondary, issue the following command:
   # vxibc -g hrdg regrecv dss_app hr_rvg [vxrvg -g hrdg -F -P dss \
   snapshot hr_rvg]

   The command vxrvg -g hrdg -F -P dss                 snapshot hr_rvg is run when the IBC message arrives on the Secondary and the command creates an instant full snapshot.

5. On the Primary, put the application that is using the Primary data volumes hr_dv01 and hr_dv02 into consistent state using the application specific method. For information on the consistent state, see step 2.
6. On the Primary, register the application name dss_app and send the IBC message using the following command:
     # vxibc -g hrdg regsend dss_app hr_rvg
7. On the Primary host, resume the application if it was suspended in step 5.

   If the RLINK is asynchronous and behind there may be a delay between the vxibc regsend and vxrvg snapshot command. During this delay, the application is running.

8. On the Secondary, use the snapshot data volumes dss-hr_dv01 and dss-hr_dv02 for running the DSS application, that is, for off-host processing.
9. When the application completes, reattach the snapshot plexes to the data volumes using the following command:
     # vxrvg -g hrdg snapback hr_rvg

   The reattach destroys the dss volumes and reattaches the snapshot plexes to their original volumes.