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| Synchronizing volumes on the local host and remote hosts | ||
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| Prev | Associating a volume to a Replicated Data Set | Next |
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| Synchronizing volumes on the local host and remote hosts | ||
|---|---|---|
| Prev | Associating a volume to a Replicated Data Set | Next |
The vradmin syncvol command enables you to synchronize remote volumes with local volumes when the volumes are not associated with an RVG and the volumes are not in use. The data in the volumes on the local host, where you enter the command, is transferred over the network to the volumes on the remote host. The volumes to be synchronized can be component volumes of a volume set. The vradmin syncvol command can also be used to synchronize a volume set itself.
Use the vradmin syncvol command only to synchronize volumes that are not part of an RVG. For example, before adding a volume to an RDS, synchronize the volume using the vradmin syncvol command, and then add it to the RDS.
Using the vradmin syncvol command, you can synchronize remote volumes with local volumes using one of the following options:
By default, the vradmin syncvol command synchronizes the volumes using difference-based synchronization. We recommend that the names of the volumes on the local and remote hosts be the same. However, you can synchronize volumes with different names on the local and remote hosts using the vradmin syncvol command.
You can supply a list of volumes to be synchronized. If you choose this method, the order of the volume names in the local and remote volume lists is important. The vradmin syncvol command synchronizes the first volume in the remote volume list with the first volume in the local volume list, and so on. Hence, the number of volumes in the local and remote volume lists must be the same. Also, the remote disk group name must be specified if volume names are different on the local and remote hosts.
To enable the vradmin syncvol command for a specific disk group on a remote host, enter the local disk group ID in the /etc/vx/vras/.rdg file on the remote host. To enable the vradmin syncvol command for all disk groups on a remote host, enter a plus (+) sign in the /etc/vx/vras/.rdg file on the remote host. For more information, see the vradmin(1M) manual page.
Before synchronizing volumes, the vradmin syncvol command displays a warning and prompts the user to confirm whether or not the data on the volumes on the remote host can be overwritten with the data on the volumes on the local host. To skip this confirmation, use the -s option with the vradmin syncvol command. The -s option to the vradmin syncvol command proves useful in scripts.
In full synchronization, all data is transferred between hosts. Use full synchronization to create initial copies of volumes. To do a full synchronization, specify the option -full.
To synchronize volumes on local and remote hosts using full synchronization
Synchronize the volumes with the following command:
# vradmin -g diskgroup -full syncvol local_vols_list \
remote_hostname....
The argument local_vols_list is a comma-separated list of volumes on the local host. The names of the volumes on the local and remote hosts are assumed to be the same.
The argument remote_hostname is a space-separated list of names of the remote hosts on which the volumes to be resynchronized reside. It must be possible for IP to resolve the remote host names.
This example shows how to do a full synchronization of the remote volumes on host london with the local volumes hr_dv01, hr_dv02, hr_dv03 in the disk group hrdg on the local host seattle. The names of the disk group and the volumes on the remote host are the same as the names of the disk group and volumes on the local host.
# vradmin -g hrdg -full syncvol hr_dv01,hr_dv02,hr_dv03 london
In difference-based synchronization, VVR compares the blocks of data between the hosts and then transfers over the network only those blocks of data that are different. Difference-based synchronization is useful when there is little difference between the data on the local and remote volumes.
To synchronize volumes on local and remote hosts using difference-based synchronization:
# vradmin -g diskgroup syncvol local_vols_list remote_hostname....
The argument local_vols_list is a comma-separated list of volumes on the local host. In this case, the names of the volumes on the local and remote hosts are the same.
The argument remote_hostname is a space-separated list of names of the remote hosts on which the volumes to be resynchronized reside. It must be possible for IP to resolve the remote host names.
This example shows how to do a difference-based synchronization of the remote volumes on host london with the volumes hr_dv01, hr_dv02, hr_dv03 in the disk group hrdg on local host seattle. The names of the disk group and the volumes on the remote host are the same as names of the disk group and volumes on the local host.
# vradmin -g hrdg syncvol hr_dv01,hr_dv02,hr_dv03 london
In this example, the names of the volumes on the remote host are different from the names of the volumes on the local host. It shows how to do a difference-based synchronization of the remote volumes hr_dvmaster and hr_dvoralog on host london with the local volumes hr_dv01 and hr_dv02 in the disk group hrdg.
# vradmin -g hrdg syncvol hr_dv01,hr_dv02 \
london:hrdg:hr_dvmaster,hr_dvoralog