reason for Analyze/disk "inconsistent highwater" message

[Amrohi Gupta]

On VMS 7.3-1 , when i run Ana/disk on system disk , i receive the following message which does not clean up even after doing a ana/disk/repair . I would appreciate if someone could tell the reason for this and any remedy action needed

%ANALDISK-I-BADHIGHWATER, file (14,1,0) SWAPFILE.SYS;1
inconsistent highwater mark and EFBLK

[Hein van den Heuvel]

First thing to find out is what the inconsistency it.
For that you should use:

$DUMP/BLOCK=COUNT=0/HEAD SWAPFILE.SYS.

Is this the active swapfile such as the name strongly suggests?

$SHOW MEM

Is it just the message which raisesa question, or is there somethign else that is a problem?

Hein.

[Wim Van den Wyngaert]

I was able to simulate the error on 7.3.
I did a restore of a backuped pagefile on a high water volume

I could repair it by doing set file/trunc xxx (but the file was not in use).

Wim

[Wim Van den Wyngaert]

Found that in dump there is a difference.
EFBL (highest block written) was at 0 on the original file and on "alloc blocks" after the restore. And back on 0 with set file/trunc.

Bug in backup ?

Fwiw

Wim

[Jan van den Ende]

Amrobi,

to begin with:

WELCOME to the VMS forum!

As SWAPFILE.SYS (just like PAGEFILE.SYS, and DUMPFILE.DMP) normally are MARKED /NOBACKUP, the _contents_ of the file are NOT recorded in a normal Backup, (but the HEADER info is, and is used to allocate the correct amount during restore) this comes as no surprise.
As a further note, the message is just -I-; informational.
Please realise that effectively, PAGEFILE & SWAPFILE "only" are mechanisms to virtually extend the physical memory, and as such the data is as volatile as in-core data. (Well, allow for an exception to this statement for PAGEFILE.SYS if the dump-to-pagefile bit is set in SYSGENs DUMPSTYLE, and a dump was written)
The concept of highwater mark is not really applicable here.

Proost.

Have one on me.

jpe

[John Gillings]

Amrohi,

Just stepping back again to make sure you know what the error actually means...

The High Water Marking is a security feature intended to prevent a process scavenging deleted data. When you delete a file, the blocks are just placed on a "free" list, and can be reused (to physically erase data use DELETE/ERASE). The file system keeps track of the highest block written to the file, so it can detect attempts to access data above that mark (in which case it returns 0s).

For a normal file we expect the EFBLK (End of File BLocK) to be less than the HWM (High Water Mark). Normally both pointers are maintained by the file system, and therefore cannot be inconsistent.

However, some files are accessed "underneath" the file system, bypassing all the code that maintains pointers. PAGEFILE.SYS, SWAPFILE.SYS and DUMPFILE.SYS are examples of such files. They can therefore wind up with inconsistent EFBLK and HWM. Since they're system files, there is no security issue. I can't remember if ANALYZE/DISK/REPAIR can fix this condition - have you tried it?
Another possibility is to SET VOLUME/NOHIGHWATER. If you don't need high water marking for security, leave it off. If you do need it try turning it back on and repeating the ANALYZE/DISK.

If not, you can safely ignore the condition for system files. Since it's an I (Informational) conditon, it shouldn't affect command procedures.

If you're really offended by the message, you may need to shutdown your system, boot from CD and issue a SET FILE/END against each reported file.

[DECxchange]

Hello,
There is an article on this if you do a search of IT Resource Center (Compaq) using %ANALDISK-I-BADHIGHWATER as the search spec:

[OpenVMS] ANALYZE/DISK Returns %ANALDISK-W-READQUOTA On AXP Or Mixed Cluster

You will also see other articles listed as well, including one forum article similar to this question, that was closed a while ago.

The first article I mentioned above talks about the QUOTA.SYS file, etc.

[Amrohi Gupta]

Thanks to all of you for throwing light on my question . As per advice of Adrian Birkett , error cleared up after doing "set file/owner=[system] swapfile.sys " .

[Amrohi Gupta]

Thanks