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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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Hi,
Will there be any processing speed/time/CPU utilization difference when reading and writing a file in the below given two cases,
1) a tape file
2) a PS file in DASD. |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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| What do YOU think? |
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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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| I face few processing time difference between them.. |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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Like ?
DASD faster or slower compared to tape? |
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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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| Ya when i ran a job with file in DASD , it ran faster than when i ran it with tape file as input.. |
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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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| Is there any way to speed up the read/write process in tape?? |
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PeterHolland
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Joined: 27 Oct 2009
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Location: Netherlands, Amstelveen
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Fast tape units, blocksize, maybe tapes are mounted manually.
But DASD processing is always faster in normal sequential processing,
but then direct tape processing is (except "stress" testing) never done. |
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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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[quote="PeterHolland"]Fast tape units, blocksize, maybe tapes are mounted manually.
What is it, 'FAST TAPE UNITS' ? |
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PeterHolland
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Joined: 27 Oct 2009
Posts: 2481
Location: Netherlands, Amstelveen
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| Google on 'FAST TAPE UNITS' and you will get lots of answers. |
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GaneshMF
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Joined: 19 Jun 2009
Posts: 27
Location: Chennai
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| Thank you!! |
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Bill Dennis
Active Member
Joined: 17 Aug 2007
Posts: 562
Location: Iowa, USA
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| No tape mount will match DASD allocation speed. The fastest is probably a scratch mount in a virtual tape server (usually < 5 secs.). Next is scratch mount from an auto-loader. |
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kailas girase
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Joined: 20 Nov 2008
Posts: 6
Location: New Bombay
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Tape Data sets not accessible for COBOL programmes, But DASD can be.
Tape is magnetic device, while DASD is optically written data.
I am not sure on above, some clarifications are expected. |
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dick scherrer
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Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
Why would you believe that tape datasets cannot be used by COBOL programs? Of course they can. . .
| Quote: |
| Tape is magnetic device, while DASD is optically written data. |
And this was posted because . . .? |
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Robert Sample
Global Moderator
Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA
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| Quote: |
Tape Data sets not accessible for COBOL programmes, But DASD can be.
Tape is magnetic device, while DASD is optically written data. |
I count at least three mistakes and one clarification in your two lines:
1. Tape data sets are easily accessed by COBOL programs.
2. DASD data sets are also easily accessed by COBOL programs.
3. Tape data is written magnetically, however the device itself is not a magnet -- it is a complicated piece of machinery that accepts electrical impulses from the CPU and translates them into magnetic bits written upon the tape
4. DASD is not optically written. DASD data is magnetic bits written upon a substrate, just like tape data is magnetic bits written upon a substrate. CD and DVD devices are optical but they don't interface much to mainframes. |
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