The T-DUMP command transfers a copy of all or selected file items in random order to tape, and also creates a tape label and writes an End-Of-File (EOF) mark on the tape after the transfer is complete.
This topic demonstrates how to make a tape containing the data from a single file. The ORDERS file is dumped to tape using the T-DUMP command. This operation does not affect the contents of the file; it can be viewed as making a copy of the file and placing it on tape.
Format
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T-DUMP [DICT] filename [item-list] [selection][HEADING "text"] [modifiers] [(options)] |
Description
The syntax follows standard INFO/ACCESS conventions, except that no output specifications are accepted. The filename identifies the source of the items that T-DUMP is to copy. If you don’t specify an item list, or if a select-list is not active, then T-DUMP copies all items in the file. T-DUMP copies the entire item; you cannot supply any output specification.
The S-DUMP command is a version of T-DUMP that accepts a sort expression (see INFO/ACCESS SORT command). The following modifiers operate in a different way when used with T-DUMP and S-DUMP than the standard way when used with other INFO/ACCESS commands:
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HEADER "text" |
Specifies heading text that is used in the tape label. |
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HEADING "text" |
Same as HEADER. |
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HDR-SUPP |
Suppresses the creation of a tape label. |
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ID-SUPP |
Suppresses listing of item-IDs during the copy-to-tape operation. |
In the following example, T-DUMP makes a tape containing the entire ORDERS file:
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>T-DUMP ORDERS DEVICE ATTACHED BLOCK SIZE: 16896 1 10107 2 10119 3 10110 4 10122 5 10113 6 10104 7 10116 8 10101 9 10134 10 10105 11 10108 12 10120 13 10111 14 10114 15 10102 15 ITEMS DUMPED. |
15 items in the ORDERS file were dumped to tape. If you try this, you will find that it takes a while to complete. That is because when you write to the beginning of the tape, the tape drive performs a separate pass to erase the tape called the erase pass or retension cycle. The data is written to tape only after the retension cycle is finished.
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NOTE |
The retension cycle is performed on 1/4-inch tapes only. |
Once the TCL prompt returns, the operation has been completed. The tape is now positioned just after a mark known as the End-Of-File (EOF) mark. At this point, use the T-DET command to detach the tape drive. Type:
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T-DET |
No message displays if the tape drive is successfully detached. You can now remove the tape from the tape drive, and make the drive once again available to other users.
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NOTE |
When the user logs off, the tape is automatically detached. |
If the tape’s write protection is on or if no write ring is present, the following message displays:
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WRITE PROTECTED CONTINUE/QUIT (C/Q)? |
Remove the write protection, then type C to continue, or type Q to quit.
If a T-DUMP is executed, but the file is empty (i.e. no items are dumped), an EOF mark is written to tape. This allows a Proc that executes multiple T-DUMPs followed by as many T-LOADs to function properly.
See Also