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**** The Hebrew University of Jerusalem **** **** Computation Center **** News Bulletin #14 18-November-1990 Today's topics: - Tape labels and using BACKUP command. - New tape media available on the VAX for backup storage. - Old files expiration dates. - BMAIL's new command: VERIFY. - Internet libraries. - Telnet 3270. - Printers and files' carriage control. o Tape labels: When you write a tape using BACKUP and a second tape is needed, BACKUP tries to compute the number of the next tape by its own. It takes the first tape label and replaces the last two characters of it with the serial number (in this BACKUP operation) of the next tape. For example, if you started writing on a tape whose label is PR1567 (and we assume that you use the same label as the external VSN of the tape), when BACKUP needs a second tape it'll ask for a tape labeled PR1502 (and for the third PR1503 and so on). This is bad since there is a tape named PR1502 which is probably not the intended one... The solution is to inform BACKUP what label it should use for the second tape. If you suspect that your job will need more than one tape use the /LABEL qualifier of BACKUP: $ BACKUP/LABEL=(first-tape-label,second-tape-label,...) ... For example, if we suspect that our BACKUP job will need 3 tapes, and we want to use tapes PR1667, PR1690, PR1610 (in that order), the BACKUP command will look like: $ BACKUP/LABEL=(PR1667,PR1690,PR1610) ... Note: It is suggested that you'll use as label the external VSN of the tape. This is the only way to enable usage of such continuation tape's labeling. Tape densities: When you intialize a tape the drive uses the lowest density available (1600 bpi in our case); if the tape was used already it will use the existing tape's density. Since most drives today accept the higher density tapes you can force INIT to use the higher density with the qualifier /DENSITY=6250 (which should be used on BACKUP also if you are writing a tape). If you have to take the tape to a different institute and need the lower density use the qualifier /DENSITY=1600. When using the higher density BACKUP's default block size (8192 bytes) wastes a large amount of tape length. If you are using BACKUP to write a tape at the higher density add the qualifier (only when writing the tape!) /BLOCK=32256 which will create blocks of 32256 bytes on the tape. To summarize, if you want to write high density tapes use the command: $ BACKUP/DENSITY=6250/BLOCK=32256... For more details consult the guide TAPES. o New tape media available: One of the tape drives used on the VAX uses tape cartridges which are known as TA90 (or more known with the IBM name of 3480). These cassetes are faster than tapes, hold more data (up to 200 Mb per cartridge), smaller and sometimes cheaper. The main disadvantages are that there are only few sites who use these cassetes on VAX systems and that you have to buy them in large quantities. Hence, these cartridges are recommended to those who have to store large amount of data for use on the local system. o Old files expiration date: The policy of the computation center is to remove files which are not touched for two months. As you probably noted this is not done. However, when disk space becomes scarce we'll start activating this files' removal without prior notice. o BMAIL's VERIFY command: A new command was added to BMAIL which verifies its internal databases integrity. When you hit the VERIFY command it'll scan your bmail's directory for files which are not entered in any folder. Such files are entered into the NEWMAIL folder. Entries in folders which have no files associated with them are deleted. Due to bugs in old versions of BMAIL you might have a few files which are inaccessible now; this command will remove their incorrect entry and enter them into the NEWMAIL folder. It is recommended to use this command once in a few weeks. o InterNet libraries: As was said in previous bulletins, there are a lot of libraries which are accessible via the InterNet. An updated copy of the guide INTERNET.LIBRARY has been replaced in GUIDES$ directory. o TN3270 - IBM systems are peculiar in the way that ASCII terminals (and thus also TELNET connections) are handled. IBM's own terminals are connected to a special controller which does all the screen management work. When you want to use a simple ASCII terminal you have to connect it to a special controller (named 7171) which does all this work. However, when you Telnet to an IBM system you don't have any such controller in the way. What you end with is a "line mode" connection which is quite impossible to work with. The solution is to do all the screen management on the local system (the one which originated the Telnet connection) and this is called "3270 mode" in telnet. The local telnet here finds out automatically when the other side is an IBM system and enters this mode transparently to you. Now you have a problem: How the function codes are mapped? A special file has been created to map the functions keys of most of the terminals used at the university to be like the ones the 7171 controller is using. This means that on a VT100 compatible terminals you have the following mapping of the keypad: Eypad's PF1, PF2, PF3 are mapped to F1, F2, F3 (i.e. the same) Keypad 7, 8, 9 are mapped to F4, F5, F6. Keypad 4, 5, 6 are mapped to F7, F8, F9. Keypad 1, 2, 3 are mapped to F10, F11, F12. Keypad's
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