QUESTIONS REGARDING 8MM TAPE (7208) BACKUP, HOW
ITEM: RTA000031208
QUESTION:
Questions regarding our 5/10GB 8mm tape.
1) On a model 980B, using the 5/10GB 8mm tape that comes standard, how
do I control whether or not the hardware compression is turned on ?
2) Same question for 7208-011 tape drive.
3) If I write a tape on a 7208-011, using hardware compression, can
I then read the tape on a 7208-001 (2.3GB) unit ?
4) What kind of compression can I expect when backing up ASCII text files
to a 7208-011 ?
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A: 1) You can control whether or not data compression is turned on when
you define the 5.0gb 8mm tape drive in SMIT. There is an option,
'Use data COMPRESSION' which gives you a choice of yes or no.
2) The 7208-011 is the 5.0gb 8mm tape drive, data compression is done
through SMIT, as mentioned above. The 7208-001 is the 2.3gb 8mm
tape drive and it does not do data compression.
3) If you write a tape on a 7208-011, using hardware compression, you
cannot read the tape on a 7208-001 as the 7208-001 only reads 2.3gb
format. The 7208-001 2.3gb tape drive can only read 2.3gb tape
written by the 7208-011 5.0gb tape drive if the tape was written
using the 2.3gb mode and without data compression.
4) When data compression is enabled, the IRDC (Improved Data Recording
Channel) algorithm takes the data stream sent to the tape drive,
and compresses the data. Hardware data compression commonly
increases tape capacity ranging from 20 percent to a doubling of
capacity. Capacity changes outside of these ranges may be possible
based on the number of repeating characters in the data. In
general, most data compression algorithms look for such things as
blank space and repeating substrings, and compress the data by
removing the blank spaces, or marking redundant text. Thus, the
effectiveness of the compression may vary based on the kind of data
being compressed. The only way to really know how effective the
compression algorithm will be with your data is to actually perform
a backup with data that is representative of the kind that your
customer has.
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This item was created from library item Q628278 CFKPM
Additional search words:
BACKUP CFKPM CNTL COMPATIBILIT COMPATIBLE COMPRESSION CONTROL
CONTROLLER CTL CTRL DRIVES IX MANAGEMENT MAY93 OP OZNEW QUESTION
RECOVERY REGARDING RISCMGMT RISCSYSTEM SOFTWARE SYS SYSTEM TAPE 7208
8MM
WWQA: ITEM: RTA000031208 ITEM: RTA000031208
Dated: 03/1996 Category: RISCMGMT
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