[Info-vax] Programming languages on VMS

[Jan-Erik Soderholm]

Den 2018-02-09 kl. 17:58, skrev Stephen Hoffman:
> On 2018-02-09 15:59:57 +0000, Jan-Erik Soderholm said:
> 
>>  do not see "backup" and "file versioning" as two features/tools that 
>> replaces one of the other. They are complements.
> 
> They are the same, differing only in the associated temporality of the 
> copies; in how long you might choose to retain the particular copies of 
> files.  BACKUP backups too are routinely thinned, with daily backups being 
> more frequent and of which some are then maintained as weekly and then as 
> monthly and then as yearly, for instance.

Our backups are done daily (each night). Each run is "incremental" (the
only mode recomended), but the actuall backup is always a complete copy
of the disks. A full restore will always restore an exact copy of the
disk as it looked like at the time the last backup was run.

> Few keep daily backups for 
> months or years, and those that do that also try to reduce that data by 
> using incrementals and deltas and compression to reduce the volume of 
> data.   Most folks treat file versions as little more than very transient 
> backups...

File versions are not "backup" at all. If some uses file versions
as "backup", so be it. But they are not.

> ...and of the effort that is involved with 
> accessing and restoring backups on OpenVMS.
> 

Not much effort.

To check for a file in the backup:

$ abc show backup <file spec> (add /state=inactive for deleted files)

To restore some file:

$ abc restore <file spec> (add output dir and file, if needed).

Both are subsecond operations for small files. And fully file version
aware.

> Sure, given file versions and the morass that is accessing files from 
> backups on OpenVMS, versions are great.  But that's less about what can and 
> should be, and more about contending with what is and what was.

Again, file versions are not a "backup". They are just a nice-to-have
that helps in the everyday work.

And accessing files in the backup is just a simple command, see above.

And to "archive" some data besides of the backups (not checked against the
live files in the nightly backup), there is the $ ABC ARCHIVE command.
Those files has to be specificaly removed from the bacup server using the
$ ABC DELETE ARCHIVE <file spec> command.