Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!YKTVMH.BITNET!PERSHNG
From: PERSHNG@YKTVMH.BITNET ("John A. Pershing Jr.")
Newsgroups: comp.lang.asm370
Subject: (none)
Message-ID: <8907181918.AA10089@jade.berkeley.edu>
Date: 18 Jul 89 18:56:05 GMT
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Reply-To: IBM 370 Assembly Programming Discussion List <ASM370%UCF1VM.bitnet@jade.berkeley.edu>
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1.  Yes, multiple machines can use *BLOCKIO in multi-write mode, as long
    as they know what they are doing.

2.  Yes, you can use the whole disk.  Note that it has to be formatted
    with fixed-length blocks, and you should avoid writing anything in
    the label block that "looks like" a CMS minidisk label, so that CMS
    doesn't inadvertently ACCESS the disk and proceed to trash it.
    ACCESS is looking for 'CMS1' as the first four bytes of the label,
    and the label is written in the third block, I believe...

    The RESERVE command is a hack to permit the minidisk to look like a
    totally legitimate CMS minidisk and still work with *BLOCKIO (using a
    non-zero offset, of course).  If this is useful, then go for it!

3.  No, you cannot use negative offsets, nor can you use an offset that
    would extend beyond the end of your allocated minidisk.

4.  Use CMS FORMAT, and then ignore the primordial directory structure
    that it deposited on the disk.

5.  Only for 3340 disks, which I assume you don't have.  The "80-byte"
    label record is simply padded out to the block size -- but you don't
    have to put a label out there if you don't want to.

      John A. Pershing Jr.
      IBM Research, Yorktown Heights