If GDS Snapshot is installed in a system where a disk array unit with the OPC function is used, backup can be performed through instant snapshot by OPC using proxy volumes without stopping services.
However, to secure consistency of snapshot data, the services must be stopped temporarily when creating a snapshot (when updating proxy volumes).
See
For securing consistency of snapshot data, see "A.2.29 Ensuring Consistency of Snapshot Data."
Figure 6.12 Backup Schedule
Information
Background Copy (OPC Physical Copy) and Backup to Tape
During the copying process, data can be backed up to tape, but the backup will impose the load on the disk array unit and may affect services using master volumes.
Note
Instant Snapshot by OPC
For use conditions of instant snapshot by OPC, see "A.2.24 Instant Snapshot by OPC." If proxy volumes are in mirroring configuration with the multiplicity of two or higher, the OPC function is unavailable for copying data from master volumes to the proxy volumes. For details, see "A.2.23 Using the Advanced Copy Function in a Proxy Configuration."
Procedure
1) Relating a proxy volume
Before creating snapshots, relate proxy volume Volume2 as a copy destination to master volume Volume1. In this example, Volume1 and Volume2 belong to class Class1. Execute the following command on a node that belongs to the scope of Class1.
# sdxproxy Relate -c Class1 -m Volume1 -p Volume2 |
See
When using GDS Management View, see "5.2.4.2 Relate."
2) Stopping the proxy volume
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 |
Information
When using GDS Management View, select a proxy volume and execute [Operation]:[Stop Volume] in the Main Screen.
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 used as a file system, use either the following methods to prevent write access to the file system. In the following examples, the mount point is /DATA.
To unmount the file system
# cd / # umount /DATA |
To write-lock the file system
# lockfs -w /DATA |
4) Updating the proxy volume
Copy data from master volume Volume1 to proxy volume Volume2 with the OPC function to update Volume2 with the data of Volume1 at the moment. Execute the following command on a node that belongs to the scope of class Class1.
# sdxproxy Update -c Class1 -p Volume2 -e instant |
When returning from the command, the update of Volume2 will be complete. Subsequently, background OPC physical copying is performed, but you may go on to step 5) without waiting until the copying is complete.
See
When using GDS Management View, see "Update" in "5.3.2.3 Backup (by OPC)." For setting of the update environment, select "Yes" to "Instant Snapshot."
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, use either the following methods to permit write access from applications to the file system on master volume Volume1. In the following examples, the mount point is /DATA.
When the file system was unmounted in step 3b-2), mount the file system.
For the ufs file system
# mount -F ufs /dev/sfdsk/Class1/dsk/Volume1 /DATA |
When write access to the file system was write-locked in step 3b-2), unlock the file system.
# lockfs -u /DATA |
5b-2) Start the services for which the master volume is used.
6) Starting the proxy volume
Start proxy volume Volume2 on a node where backup to tape is performed.
# sdxvolume -N -c Class1 -v Volume2 |
Information
When using GDS Management View, select a proxy volume and execute [Operation]:[Start Volume] in the Main Screen.
7) Confirming the completion of copying
Confirm that the copying is complete.
# sdxinfo -S -c Class1 -o Volume2OBJ CLASS GROUP DISK VOLUME STATUS ----- ------ ------ ------ ------- ------- slice Class1 Group2 Disk3 Volume2 ACTIVE slice Class1 Group2 Disk4 Volume2 ACTIVE |
If all the displayed slices' STATUS fields are "ACTIVE", copying is complete. If the copying is still in progress, "COPY" will be displayed in the STATUS field.
8) 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.
8a) When backing up data held in a raw device with the dd(1M) command
# dd if=/dev/sfdsk/Class1/rdsk/Volume2 of=/dev/rmt/0 bs=32768 |
8b) When backing up the ufs file system with the tar(1) command
8b-1) Before mounting
Check and repair consistency of the ufs file system on the proxy volume with the fsck(1M) command. When the file system on the master volume was unmounted in step 3b-2), skip this step.
# fsck -F ufs /dev/sfdsk/Class1/rdsk/Volume2 |
8b-2) Mounting the snapshot
Mount the ufs file system on proxy volume Volume2 on temporary mount point /DATA_backup.
# mkdir /DATA_backup # mount -F ufs /dev/sfdsk/Class1/dsk/Volume2 /DATA_backup |
8b-3) Backing up to tape
This example shows the procedure when data is backed up to a tape medium of tape device /dev/rmt/0 with the tar(1) command.
# cd /DATA_backup # tar cvf /dev/rmt/0 . |
8b-4) Unmounting the snapshot
Unmount the file system mounted in step 8b-2).
# cd / # umount /DATA_backup # rmdir /DATA_backup |
8c) When backing up the ufs file system with the ufsdump(1M) command
8c-1) Before mounting
Check and repair consistency of the ufs file system on the proxy volume with the fsck(1M) command. When the file system on the master volume was unmounted in step 3b-2), skip this step.
# fsck -F ufs /dev/sfdsk/Class1/rdsk/Volume2 |
8c-2) Backing up to tape
This example shows the procedure when data is backed up to a tape medium of tape device /dev/rmt/0 with the ufsdump(1M) command
# ufsdump 0ucf /dev/rmt/0 /dev/sfdsk/Class1/rdsk/Volume2 |
9) Stopping the proxy volume
After backing up to tape, stop Volume2 to protect data in proxy volume Volume2. If Class1 is a shared class, specify the "-e allnodes" option to stop Volume2 on all the nodes.
# sdxvolume -F -c Class1 -v Volume2 |
Information
When using GDS Management View, select a proxy volume and execute [Operation]:[Stop Volume] in the Main Screen.
10) Breaking the proxy volume
When no more online backup is to be executed, cancel the relationship between master volume Volume1 and proxy volume Volume2.
# sdxproxy Break -c Class1 -p Volume2 |
See
When using GDS Management View, see "5.5.5 Breaking a Proxy."
11) Re-executing online backup
To perform online backup again, go back to step 3).
