Re: Ghost queues

[Stefan Sievert]

Hey Jim,
I dug this out from my archives (May 1st this year), hope it helps.
Stefan
---
Hi all,
hope someone can answer a query from an MQ newbie. The environment
is MQ 5.3 running under Solaris 8.
The queues directory contains a number of directories with names of the
form

!!GHOST!3E0E3279!2!CD44B324!1317

These directories appear to be the same as a "normal" queue directory
containing a single q file. I can find no reference in the documentation
as
to what these directories are and how they are associated with mq queues.
I
suspect that they are associated with the temporary dynamic queues we are
using but some seem to remain after the queue manager has been stopped and
started. Is it safe to delete them once the qmgr has been stopped? I would
appreciate if anyone can provide an explanation of how/when/why they are
created and deleted or point me to the relevant documentation.
Thanks.
Stuart Bourne.
Hansen Technologies
Stuart,

Users should NEVER need to use OS commands to modify the queue manager file
tree. It would not be safe to delete files or directories associated with
'ghost queues'.
Ghost queues were introduced in 5.2 as part of the line item to reuse
resources associated with dynamic queues. This line item resulted in very
significant performance improvements to the creation of both permanent
dynamic and temporary dynamic queues. In order to facilitate the reuse of
the queue resources the queue file location is not based upon the queue
name but is of the form "!!GHOST!id1!Counter1!id2!Counter2".
The queue manager tries to keep pools of reusable queue objects associated
with the model queue from which the dynamic queues were created. The size
of these pools is heuristically tuned. In emergencies the pool can be
emptied by deleting and redefining the model queue.
Cheers,
P.
Paul G Clarke
WebSphere MQ Development
IBM Hursley
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