[Info-vax] VMS defragmenters

[VAXman- at SendSpamHere.ORG]

In article <zf0mbSCtiTE2 at eisner.encompasserve.org>, koehler at eisner.nospam.encompasserve.org (Bob Koehler) writes:
>In article <00A8A533.B575173B at SendSpamHere.ORG>,   VAXman-  @SendSpamHere.ORG writes:
>> 
>> $ COPY VMB.EXE and then delete the original.  Happy rebooting.
>
>   I think VMB.EXE and some of the other files have a need to a pixed
>   id in the index, or a fixed header location (which may be the same),
>   that's not the same as not being able to move the content.

VMB.EXE and APB.EXE need to be contiguous.  They are mapped by a primordial
file system.

To find the VMB.EXE or APB.EXE, the LBN is written into the first LBN of the
boot (system) disk.  I don't have a VAX booted at the moment but on my Alpha
I have:

$ DUMP/HEADER/BLOCK=COUNT=0 SYS$SYSTEM:APB.EXE
Dump of file SYS$COMMON:[SYSEXE]APB.EXE;2 on 20-APR-2009 16:01:40.21
File ID (55863,18,0)   End of file block 1144 / Allocated 1155

                             File Header

Header area
    Identification area offset:           40
    Map area offset:                      100
    Access control area offset:           255
    Reserved area offset:                 255
    Extension segment number:             0
    Structure level and version:          2, 1
    File identification:                  (55863,18,0)
    Extension file identification:        (0,0,0)
    VAX-11 RMS attributes
        Record type:                      Fixed
        File organization:                Sequential
        Record attributes:                <none specified>
        Record size:                      512
        Highest block:                    1155
        End of file block:                1145
        End of file byte:                 0
 :
 :
Identification area 
    File name:                            APB.EXE;2
    Revision number:                      170               
    Creation date:                         5-JAN-2004 20:17:22.05   
    Revision date:                        10-MAR-2007 15:25:05.12
    Expiration date:                      <none specified>
    Backup date:                          <none specified>
    
Map area    
    Retrieval pointers                    
        Count:       1155        LBN:   13456520

Checksum:                                 13239    

As you can see, APB.EXE is a contiguous 1155 blocks starting at 13456520.

$ Y=13456520
$ SHOW SYMBOL Y
  Y = 13456520   Hex = 00CD5488  Octal = 00063252210

$ DUMP/BLOCK=COUNT=1 SYS$SYSDEVICE:
Dump of device SYS$SYSDEVICE: on 20-APR-2009 16:04:53.31

Logical block number 0 (00000000), 512 (0200) bytes

 03039401 001E65C0 FFFFFFFF 15C600A0 ..AE.....Ae...... 000000
 8BDFFF76 905F0000 000501FB 000609F7 /...u....._.v.s. 000010
 20535953 534D5650 58410087 80FDFF74 t.y...AXPVMSSYS  000020
 74737973 20616870 6C412020 20202020       Alpha syst 000030
 0000000A 0A0D2020 206B7369 64206D65 em disk   ...... 000040
 00000000 00000000 00000000 00000000 ................ 000050
 00000000 00000000 00000000 00000000 ................ 000060
 :
 :
 00000000 00000000 00000000 00000000 ................ 0001A0
 00000000 00000000 00000000 00000000 ................ 0001B0
 00000000 00000000 00000000 00000000 ................ 0001C0
 00000000 00000000 00000000 00000000 ................ 0001D0
 00000000 00CD5489 00000000 00000477 w........TI..... 0001E0
----------^^^^^^^^
 089CFC53 2A113530 00000000 00000000 ........05.*Su.. 0001F0


APB.EXE maintains a normal VMS image header block so the LBN is one block
into the file.


-- 
VAXman- A Bored Certified VMS Kernel Mode Hacker    VAXman(at)TMESIS(dot)ORG

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