Hi,
I have a 740 filer and a tape library attached to it. When I do 'restore tvf' to see what's on the tape, all the disks start spinning intensively, as if I'm actually extracting from the tape rather then listing tape's contents. I'm not sure I understand why that's happening.
Any idea?
Restore will read in all of the directory information (conveniently located at the beginning of the tape) into some temporary files. All the directory info is compacted, so it doesn't take much space.
Anyway, restore reads through those files to determine the table of contents of the files on the tape. The directory info is necessary because that is the only place where file names are stored on tape. And we like to keep it on disk, since we need to move fairly randomly through that information. To do that on a tape would be unwieldy and easy to get wrong.
By reading through the directories restore tf prints those file names for you.
So you should see a short burst of write activity followed by read activity.
One last note for everybody: You might try running restores without the 'v' option. I know that it prints out a lot of useful information. However, when running restores of data (especially restore rf) the performance impact of having to print all that information can be as much as 50% CPU and/or a 50% slowdown of restore. It won't have nearly the same effect on a restore tf, since we're already printing out a lot of information. Just something to think about. :)
Stephen Manley Data Availability and Management Trailblazer