Re: To Recover a deleted file from MVS Backup
- From: "Joel C. Ewing" <jcREMOVEewing@xxxxxxxxxxx>
- Date: Sun, 22 Jan 2006 03:27:13 GMT
This may leave many with a dangerously optimistic misconception about how much backup activity is done for you automatically on MVS and how omniscient MVS is about application backup requirements.
The backups to which you refer are backups that are taken by the product DFSMShsm, an optional product of z/OS which might not be active in all installations. HSM is highly customizable and also tied to System Managed Storage (SMS) definitions, which are customized and unique to a specific MVS installation. The installation would have to define an SMS Management Class with the autobackup attribute, and a dataset would have to be associated (implicitly or explicitly) with such a management class in order to be eligible for autobackup.
Autobackup is scheduled for a specific, installation-chosen, time period during the 24-hour day and autobackup of a specific dataset will be done at most once a day during that time period. The installation can also choose how many backups will be retained for that management class and whether a minimum number of days must have elapsed from a prior backup. If a dataset undergoes multiple changes before it becomes eligible for autobackup again, only the last state of the dataset will be saved in an autobackup. Also, if the dataset can possibly be changed during the daily autobackup process (which may run for several hours), then you can't even predict in advance whether the backup up version of that dataset will be taken before or after it changes.
Bottom line, you have to know and understand the conventions that are in place at your specific MVS installation relating to autobackup eligibility and scheduling. If this means you have an application that isn't adequately protected for recovery or re-run, it is the application implementer's responsibility to create required backups at the required times and with the required retention cycle. MVS has no way to guess what the requirements might be for an arbitrary application.
mftips@xxxxxxxxx wrote:
In Mainframes, MVS takes backup of files/datasets, every time they are changed. Also it keeps backup of these changed versions at any point of time. So, at any point of time we can recover deleted datasets as well as its previous versions.
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- From: mftips@xxxxxxxxx
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