Some simple answers as requested - Each hardware vendor supplies it's own software providing the 'snapshot' functionality. Changing hardware may necessitate changing jobs or parameters to accommodate the different hardware functionality provided.
There are basically 2 levels - Full Volume & Dataset Level. In my experience, the full volume functionality is generally part of the deal when you buy the hardware. If it wasn't, you need to bargain harder. Dataset level may or may not have an extra cost - again depends on your deal. Full Volume level provides an identical copy of the volume - volser, datasets, everything. Because it's an identical volume, you can't bring it on line to the same LPAR, but you can bring it online to another LPAR if the original volume is not already online there. There are products which allow you to back the copy up while it is offline. These issues limit dataset accessibility and carry some risk if you need to understand if you use the volume on another system. There are also issues with multi-volume datasets. For the purposes of your discussion, I don't think you're interested in Full Volume. Now Dataset Level Flashcopy is more interesting because you can flash datatsets (even multi-volume ds's) to a new name. The new dataset is nearly instantaneously available while the actual physical copy happens in the background. This new dataset is available to other programs & utilities. There are also issues to consider when there are multiple subsystems involved. Luckily I don't have to deal with them except at DR as we can fit into a single subsystem. HTH's dd keller Please bear with me, but this is an area where my knowledge is very limited. I'd need a quick and simple answer for a discussion here. Don't go too much into various possibilities. I just need to get the big picture for now. Snapshot functionality is offered by DASD subsystems, not by z/OS, right? What granularity can one get with snapshorts? - On the sub-volume level, i.e. on the individual MVS data set level ? - On a multi-volume level within one storage subsystem? - On a multi-volume level within multiple storage subsystems? -How can an application access the data in a snapshot, i.e. to create a point in time backup? -Is it reasonable to program, say in Java or PL/1, to backup data with the help of snapshot technology? - Does this require authorized functions? -- Peter Hunkeler ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN This e-mail message and all attachments transmitted with it may contain legally privileged and/or confidential information intended solely for the use of the addressee(s). If the reader of this message is not the intended recipient, you are hereby notified that any reading, dissemination, distribution, copying, forwarding or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately and delete this message and all copies and backups thereof. Thank you. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
