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Backing up proves an emulator just works

TapebackupProving the concept of emulation for MPE operations is becoming popular this year. To offer evidence, longtime managers of 3000 servers check out the mundane as well as the specific tasks that drive their companies. Backup is a backbone of real IT -- and one evaluator shared his pleasure in watching the Stromasys CHARON HPA/3000 product improve on such an essential mission.

The process is somewhat different than on a physical HP 3000. First off, you can do backups while people are still on the 3000, if you have backup software to support that. When you configure the emulator, you specify a virtual tape drive, similar to the way you specify the virtual disc drives, with each virtual device pointing to a file in the Linux environment. Then, when you run MPE's STORE command, CHARON puts the data in the file associated with that virtual tape drive. When the backup is done, you can copy that file (using standard Linux commands) to some other backup media for archival. 

One very nice thing I found is that CHARON doesn't ever run out of 'tape' on a backup. It just keeps growing the file as needed. When I configured our emulator environment, I configured the tape drive at 8GB, thinking that would be enough. However, when I finished the software install and had copied our test data, I had about 10GB worth. When I did the full system store, Charon successfully backed up everything and expanded the virtual tape drive size to be 10GB.

Later, when I did just a SYSGEN to the virtual tape drive, the file was only 5GB. No more having to worry about what tape density you're using -- and no more getting the 'please insert next tape' message on a backup. 

Backup is just the latest example of "it just works," the motto that the emulator prospects come away with once they're done with a proof of concept. A serious number of them will be using the product to extend the life of MPE applications that are destined for replacement. Until that day, everything has to be backed up. Of course, the real test of any backup process is to restore your data.

To do an MPE restore, you find the Linux file that corresponds to the backup tape you desire, copy it back to the emulator directory (using the appropriate Linux commands), name it the same as the virtual tape drive you configured in Charon, and do an MPE restore. Charon reads the file as if it were a backup tape and finds the appropriate MPE file to restore.  It works the same way for SYSGens, except that it creates a bootable image that you can boot from later. 

At this stage, everything works as expected with CHARON and its backups. "You don't need to 'pre-build' the tape file before a STORE," says product manager Paul Taffel. "CHARON rewrites any pre-existing file before starting a Store, and the file will then grow as large as needed. The :DEVCTRL command must be used to put a virtual tape online before any STORE or RESTORE operation."

The 3000 manager who was proving the emulator concept was satisfied. But it will be later in the year before the emulator takes over the 3000 hardware's work.

"All in all, we were pleased with what we saw," he said. "But when an internal project needed more resources, I was pulled off all of the other projects I was working on, including the CHARON testing, to devote 90 percent of my time to this other project. We were almost ready to begin the procurement process, once I had verified that PowerHouse Web worked. I hope to resume testing when my current project is finished."