Five things to know about FlashCopy and IBM i
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In times where business demands for ever rising availability levels on systems with a high workload, backup windows are closing fast. Offline backups become less and less possible and the need for an online backup solution is rising. The use of external storage and FlashCopy provides a possible solution in this area.
Here are 5 interesting facts to know about FlashCopy and IBM i:
1. FlashCopy provides a point-in-time copy
FlashCopy is a function of IBM storage systems. It allows you to create a point-in-time copy of a logical volume. By doing a FlashCopy, a relationship is established between a source volume and a target volume. Both are considered to form a FlashCopy pair. Typically, large applications such as databases have their data spread across several volumes, and their volumes should all be FlashCopied at exactly the same point-in-time. FlashCopy offers consistency groups, which allows multiple volumes to be FlashCopied at exactly the same instance. When the FlashCopy is started, the relationship between source and target is established within seconds by creating a pointer table, including a bitmap for the target.
2. FlashCopy is integrated into PowerHA for IBM i
When using either DS8000 or a member of the IBM Storwize family of products, PowerHA for IBM i provides an integration between the IBM i environment and the storage system. Using PowerHA, you can start a FlashCopy for an IASP by using a simple CL command. There is no need to use the storage management GUI or to develop individual scripts to communicate with the storage system.
3. FlashCopy provides an option for online backups
In order to take a consistent FlashCopy (remember that FlashCopy only works on the storage system and not on data in main memory), you should quiesce the IASP containing your application. This ensures that data has reached transaction boundaries and that main storage content is written to disks. While the application is quiesced, all transactions are on hold, but they are not ended. You can then create the FlashCopy, which only takes a very short amount of time, and resume access to the IASP. The copy of the IASP can be varied on to another LPAR and the backup operation can take place while users can again access the original data.
4. BRMS has been enhanced to work together with FlashCopy
When doing a save from a FlashCopy, the original data and the original system do not know that a save has taken place. This means that for example, the Backup, Recovery and Media Services (BRMS) recovery reports would not show correct instructions for restoring data. Therefore, BRMS has been enhanced to provide support for a FlashCopy environment. Using the correct setup, the original system “thinks” that it has done the save operations itself and the recovery reports on the original system do reflect that a save was done from the FlashCopy. Using the Advanced feature of BRMS, it is even possible to set the save timestamp to the time the FlashCopy was taken instead of the time that the actual save occurred.
5. FlashCopy is also possible for an entire system backup
The use of FlashCopy is also possible for an entire system, and not only for an IASP. However, you need to be aware that in this scenario, there is no integration with PowerHA. Instead, you have to create your own scripts to ensure proper communication between IBM i and the storage system. Also, you are creating a complete identical copy of your production system, including IP addresses. Make sure that you understand exactly what you are doing when you power up this copy. Alternatively, the Advanced Copy Services from Lab Services provides a tested environment for full system FlashCopy operations. BRMS also provides documented steps for a full system FlashCopy scenario.
For more information about Flashcopy and IBM i see the IBM Redbooks publication IBM
Sabine Jordan is a Consulting IT Specialist working in IBM Germany. She has worked as a Technical Specialist in the IBM i area for more than 20 years, specializing in high availability. She has worked on IBM PowerHA SystemMirror for i implementations for both SAP and non-SAP environments using geographic mirroring, IBM DS8000, and SVC remote copy services. In addition, Sabine presents and delivers workshops on IBM PowerHA SystemMirror for i and high availability and disaster recovery.