analyze_multics (azm) select_dumps mishandles dump identifiers that share same last nibble

[Gary Dixon]

The analyze_multics (azm) subsystem cannot properly change between dumps whose dump ID shares the same last nibble. For example:

azm

azm:  lsd >old_dumps>*
Dumps in >old_dumps:
     021817.1749.0.7
     070419.2007.0.6
     030121.0630.0.7
     091921.0738.0.21
     091921.0752.0.22
     091921.0758.0.23
     091921.2220.0.25

azm:  sld >old_dumps>021817.1749.0.7
  ERF 7   in directory >old_dumps dumped at 02/18/17  1749.6 pst Sat.
  System-ID MR12.6f Version-ID MR12.6f
Proc   9 DBR  16630134 running        on cpu a   GDixon.Multics.a

azm:  sld >old_dumps>030121.0630.0.7
  ERF 7   in directory >old_dumps dumped at 02/18/17  1749.6 pst Sat.
  System-ID MR12.6f Version-ID MR12.6f
Proc   9 DBR  16630134 running        on cpu a   GDixon.Multics.a

The first sld request properly selects the first dump in the list. The second sld request should pick the third dump in the list. But instead it re-selects the first dump in the list. I presume this is because both dumps have an ID with .7 as the last nibble, and the last nibble is the preferred selector when there are no duplicates in the list. That is, the second dump in the list can be selected more easily with the request:

azm:  sld >old_dumps>6
  ERF 6   in directory >old_dumps dumped at 07/04/19  1907.2 pst Thu.
  System-ID MR12.6g4 Version-ID MR12.6g4
Proc   1 DBR     52402 running        on cpu a   Idle.SysControl.a

But when two dumps share the last nibble value, azm reports an error.

azm:  sld >old_dumps>7

Error:  amu_find_system_dump_ error by amu_find_system_dump_$fdump|1525
(>tools>bound_amu_)
Multiple dumps numbered 7 in >old_dumps.
r 15:25 0.797 522 level 2

The avoidance for this bug is to quit out of azm, and re-enter, then select the 3rd dump in the list giving its longer pathname to above the error about duplicate ID nibbles.

For example:

pi

azm:  q
r 15:29 0.199 2

azm

azm:  sld >old_dumps>030121.0630.0.7
  ERF 7   in directory >old_dumps dumped at 03/01/21  0630.3 pst Mon.
  System-ID MR12.7 Version-ID MR12.7
Proc   6 DBR  16625434 running        on cpu a   Backup.SysDaemon.z

[Eric Swenson]

​https://s3.amazonaws.com/eswenson-multics/public/mcrs/MCR10129_azm_2.4_v1.8.pdf

[Eric Swenson]

Fixed in MR12.8-1054.

[Eric Swenson]

Apparently this issue was not fixed with MR12.8-1054.

[Eric Swenson]

Fixed in MR12.8-1055.