[comp.os.vms] ACLs Cause Systems Manager to be Hung

r_wright@mail.uwa.oz (01/22/88)

>....  The problem is that sometimes the ACL on one of these
>directories gets munged somehow, causing the directory to be (as near as I can
>tell) TOTALLY INACCESSIBLE.  You can't look at, much less use, the files in the
>directory; you can't copy anything; and you can't delete or rename the
>directory.  All of these operations result in an error message SYS-F-IVACL,
>Invalid Access Control List.  I can't even find this error message in _System
>Messages_ so I'm even more confused.

The problem you describe existed in 4.4 and probably still exists in 4.5 - I
have no knowledge of the behaviour in 4.6. The following conditions contribute
to increasing probability of occurrence:-

	Excessive fragmentation of the volume

	Long ACLs - typically, files which experience the problem have an ACL
		    which will not fit in a single header, leading to...

	Extension headers

	A (presumed) timing problem, probably related to the IO rate at the time

A Digital spokesperson indicated to me that "this was an excessive-load
condition, which tests VMS beyond the design parameters" - or somesuch garbage.

You can often get to the file with the 'try again later' approach.

Mostly you can prevent it by BACKUP/save/restore (refresh) or by running a 
defrag utility. Avoid long ACLs - you never really need them anyway.

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