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INZTAP & CLEAR Parameters

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  • INZTAP & CLEAR Parameters

    From the IBM Knowledge Center:
    Clear (CLEAR)


    Specifies whether all previous labels and data are deleted from the tape when it is initialized. If the volume must be cleared of all data, it is spaced from the location of the initializing volume label or tape markers to the end of the tape marker. *NO Existing data is not deleted. Even though the existing data is not deleted, the data on the volume is not accessible after the volume has been initialized for use. *YES After the beginning of the tape has been initialized for use, the rest of the data on the tape is deleted. The *YES value is needed only if there are security concerns with the old data. If *YES is selected, the initialize operation can take a long time.
    https://www.ibm.com/support/knowledg...m#INZTAP.CLEAR

    I can understand if parameter is set to "*YES", it takes a long time to completely erase all data on tape. However, for "*NO" parameter, it states that existing data is NOT deleted. My question is, does the inaccessible data still remain on the tape itself taking up storage? Or, does it remain on tape and get overwritten when additional space is needed later on? If anyone has any docs to reference or has any info I'd appreciate it. Thanks!

  • #2
    It's not really any different to HDDs. When you delete a file, all you do is wipe the "index" to the file but the actual data remains on the disk (which is how recovery tools work) but you do get your space back. Not sure how the mechanics work on a tape but if you INZTAP with clear *NO, it starts writing at the beginning overwriting old data. I'd guess it adds the end of data marker straight after the beginning of tape marker or something like that.

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    • #3
      Originally posted by john.sev99 View Post
      It's not really any different to HDDs. When you delete a file, all you do is wipe the "index" to the file but the actual data remains on the disk (which is how recovery tools work) but you do get your space back. Not sure how the mechanics work on a tape but if you INZTAP with clear *NO, it starts writing at the beginning overwriting old data. I'd guess it adds the end of data marker straight after the beginning of tape marker or something like that.
      That's what I assume as well, CLEAR(*NO) just overwrites as you go. CLEAR(*YES), I assume, from Google searching, it "zeroes" out all the data on tape for security measures to make the data unrecoverable.
      Last edited by LiQuiD_FuSioN; September 18, 2018, 09:10 AM. Reason: Edit: Meant to say "CLEAR", not "CHECK."

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      • #4
        Not sure if you mis-typed, but the CHECK parameter is different than the CLEAR parameter.

        CHECK, as its name implies, checks for active files on the tape prior to initializing it, and issues an error message if found and the command does not proceed with the initialization.

        Cheers,

        Emmanuel

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        • #5
          Originally posted by EmmanuelW1 View Post
          Not sure if you mis-typed, but the CHECK parameter is different than the CLEAR parameter.

          CHECK, as its name implies, checks for active files on the tape prior to initializing it, and issues an error message if found and the command does not proceed with the initialization.

          Cheers,

          Emmanuel
          Yes, sorry about that, I meant "CLEAR." Thanks.

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