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Date: July 19, 1983 13:46
From: KIM::SUTTLES
To: @SYS$MAIL:COINOP
Due to a severe increase in demand, we are forced to state some kind of policy on private archival backup tapes. Effective immediately, anyone can have a backup done on a BYOT (bring your own tape) basis. If you provide a tape to Sharron, along with a specification of files to be backed up, she will process the backup and return the tape. Deletion of the files is UP TO YOU. The safekeeping of the tape is also your own responsibility. We will continue the current backup schedule as normal (every noon, to be kept til noon the next day; every morning, to be kept a week, except for fridays, which are kept a month, except for the LAST friday of each month, to be kept a year). These tapes we will retain; but we don't have the storage nor the media for everyone to have a tape or two of their own. If you choose this approach, redundancy is YOUR HEADACHE. If something happens to your own tape, and it is not on any of the tapes we still have, your data will be lost. Note that there is the possibility of damage to the tape, as well as accidental erasure, when adding to an existing set. It is reccommended that you keep separate tapes for separate projects, instead of trying to "cheap out" and fit twenty sets on one tape. If sets one thru 19 get blown away when you add number 20, you would be very upset. The moral of the story is that if the data is important enough to keep, you should keep it as a set, intact, and seperate. We will not mount the media write-enabled for a restore; but in order to add to the set, you run the risk of accidental overwrite. All of the above applies to floppies, as well as tape; floppies are a little more convenient to store, but don't hold as much. Rough figures follow: Tape (2400 ft, 8KB block size) = 40MB storage, or 80,000 disk blocks (figure 75K blocks after backup adds its own overhead) Floppies (single density, our default) = .25MB, or 500 disk blocks. Floppies (double density, YOU MUST SPECIFY) = .5MB, or 1,000 disk blocks. If you want double density, all of the floppies to be written on must be pre-initialized before the backup starts. Therefore, you need to KNOW beforehand just how many floppies are to be used. Floppies can be file structured, meaning they can have directories on them, and are much easier to update (as opposed to backup sets, which have to be created all at the same time). Multi-volume sets only apply to the backup program; if it won't fit on one floppy, you need a backup set on more that one floppy, or one or more tapes. Do a $DIR/SIZ to find out how much data you have. This should probably make the answer obvious. If I can help you determine your needs, give me a call. sas
Jul 19, 1983