This subsection describes the procedures for backing up volumes through the use of synchronization snapshot of GDS Snapshot.
Procedure
1) Joining a proxy volume
To prepare for creating a snapshot, relate and join proxy volume Volume2 as the copy destination of master volume Volume1 to the master volume. This example shows the procedure when Volume1 and Volume2 belong to Class1. Execute the following commands on a node that belongs to the scope of class Class1.
1-1) Stop proxy volume Volume2. If Class1 is a shared class, specify the "-e allnodes" option to stop Volume2 on all nodes.
# sdxvolume -F -c Class1 -v Volume2 |
1-2) Relate and join proxy volume Volume2 to master volume Volume1.
# sdxproxy Join -c Class1 -m Volume1 -p Volume2 |
After returning from the command, synchronization copying from Volume1 to Volume2 is executed.
Information
Relating and Joining a Pair of Groups
If the proxy group includes volumes, remove the volumes before executing the sdxproxy Join command, and also specify the -a option for this command.
Example)
Relate and join proxy group Group2 to master group Group1. Assign volume names Proxy1 and Proxy2 to the proxy volumes automatically created in Group2 corresponding to volumes Volume1 and Volume2 in Group1.
# sdxproxy Join -c Class1 -m Group1 -p Group2 \ |
2) Confirming the completion of copying
Confirm that the synchronization copying is complete.
# sdxinfo -S -c Class1 -o Volume2
OBJ CLASS GROUP DISK VOLUME STATUS
----- ------ ------ ------ ------- -------
slice Class1 Group2 Disk3 Volume2 STOP
slice Class1 Group2 Disk4 Volume2 STOP |
If all the displayed slices' STATUS fields are "STOP", synchronization copying is complete. If the synchronization copying is still in progress, "COPY" will be displayed in the STATUS field.
3) Stopping the services
To secure consistency of snapshot data, stop the services before creating a snapshot and restrain the master volume from being written in.
3a) When the master volume is being used for a cluster application
Inactivate the cluster application.
3b) When the master volume is not being used for a cluster application
3b-1) Stop the services for which the master volume is being used.
3b-2) When the master volume is being used as a file system, unmount the file system. This example shows the procedure when the mount point is /DATA.
# cd / # umount /DATA |
4) Parting the proxy volume
Create a snapshot of master volume Volume1 by parting proxy volume Volume2 from master volume Volume1. Execute the following commands on a node that belongs to the scope of class Class1.
# sdxproxy Part -c Class1 -p Volume2 |
5) Resuming the services
5a) When the master volume is used for a cluster application
Activate the cluster application.
5b) When the master volume is not used for a cluster application
5b-1) When the master volume is used as a file system, mount the file system. This example shows the procedure when the ext4 file system on master volume Volume1 is mounted on mount point /DATA.
# mount -t ext4 /dev/sfdsk/Class1/dsk/Volume1 /DATA |
5b-2) Start the services for which the master volume is used.
6) Backing up to tape
Back up the snapshot data on the proxy volume to tape. Execute the following commands on a node that belongs to the scope of class Class1.
See
For details on the backup methods, see the manuals of file systems to be backed up and used commands.
6a) When backing up data with the dd(1) command
# dd if=/dev/sfdsk/Class1/dsk/Volume2 of=/dev/st0 bs=32768 |
6b) When backing up the ext4 file system with the tar(1) command
6b-1) Before mounting
Check and repair consistency of the ext4 file system on the proxy volume with the fsck(8) command. When the file system on the master volume was unmounted in step 3b-2), skip this step.
# fsck -t ext4 /dev/sfdsk/Class1/dsk/Volume2 |
6b-2) Mounting the snapshot
Mount the ext4 file system on proxy volume Volume2 on temporary mount point /DATA_backup.
# mkdir /DATA_backup |
6b-3) Backing up to tape
This example shows the procedure when data is backed up to a tape medium of tape device /dev/st0 with the tar(1) command.
# cd /DATA_backup |
6b-4) Unmounting the snapshot
Unmount the file system mounted in step 6b-2).
# cd / # umount /DATA_backup # rmdir /DATA_backup |
7) Rejoining the proxy volume
To perform online backup again, follow the procedures below on a node that belongs to the scope of class Class1 and then go back to step 2).
7-1) Stop proxy volume Volume2. If Class1 is a shared class, specify the "-e allnodes" option to stop Volume2 on all nodes.
# sdxvolume -F -c Class1 -v Volume2 |
7-2) Rejoin proxy volume Volume2 to master volume Volume1.
# sdxproxy Rejoin -c Class1 -p Volume2 |
After returning from the command, synchronization copying from Volume1 to Volume2 is performed.
8) Breaking the proxy volume
When no more online backup is executed, cancel the relationship between master volume Volume1 and proxy volume Volume2. Execute the following command on a node that belongs to the scope of Class1.
# sdxproxy Break -c Class1 -p Volume2 |
