Magnetic tape position lost

[Wim Van den Wyngaert]

I make a remote backup (=convert) to a TZ87 on VMS 7.3.

The log :
$ init/media=compac/override=expiration SBETV1$MKD300: V80940
$ open/read/write xxx sys$net
$ mount/rec=8192/block=8192 SBETV1$MKD300: V80940
%MOUNT-I-MOUNTED, V80940 mounted on _SBETV1$MKD300:
$ convert/fdl=sys$input/stat xxx SBETV1$MKD300:DVP_PH_D1.bck
record
format fixed
size 8192

CONVERT Statistics
Number of Files Processed: 1
Total Records Processed: 66960 Buffered I/O Count: 133927
Total Exception Records: 0 Direct I/O Count: 66962
Total Valid Records: 66960 Page Faults: 26
Elapsed Time: 0 00:09:14.89 CPU Time: 0 00:00:23.73
$ close xxx
$ dismount/nounload SBETV1$MKD300:

Now I want to add a 2nd save set to this tape.
The log :
$ open/read/write xxx sys$net
$ mount/rec=8192/block=8192 SBETV1$MKD300: V80940
%MOUNT-I-MOUNTED, V80940 mounted on _SBETV1$MKD300:
$ convert/fdl=sys$input/stat xxx SBETV1$MKD300:DVP_PH_D2.bck
record
format fixed
size 8192
%CONV-F-OPENOUT, error opening SBETV1$MKD300:[WVW]DVP_PH_D2.BCK; as output
-RMS-E-CRE, ACP file create failed
-SYSTEM-F-TAPEPOSLOST, magnetic tape position lost

Any ideas why ? Tried 3 times with different file size of first save set : all 3 failed.

Wim

[Karl Rohwedder]

Wim,

perhaps you could try to position the tape at the end maually (SET MAGTAPE/SKIP=END)before writing to it?

regards Kalle

[Wim Van den Wyngaert]

Kalle,

Set magtape is only valid when mounted foreign (see help).

Wim

[Martin Vorlaender]

Wim,

$ help/mess TAPEPOSLOST

TAPEPOSLOST, magnetic tape position lost

Facility: SYSTEM, System Services

Explanation: The magnetic tape ancillary control process lost the current position on the tape and cannot continue processing.

User Action: Close all open files. Dismount and remount the tape and position it to the desired position, if possible. If the error persists, the tape may be defective.

cu,
Martin

[Wim Van den Wyngaert]

Alternate solution :

Anyone with a remote backup solution in DCL that can handle multiple save sets ?

Wim

[Ian McKerracher_1]

Hello Wim,

Can you list the first saveset once it has been written to tape. I'm wondering whether the tape position has been lost before the procedure attempts to write the second saveset to tape.


Regards,

Ian

[Wim Van den Wyngaert]

Ian,

yes I can see it after 1 save set is on it.

New report. Btw : TZ89, not TZ87 but with TK87 density.

It seems that from the moment I did the /fast=never, the tape remembers to behave correctly.

So, I added a mount/for and set mag/fast=never to the beginning of my backup procedure. IT WORKS !!!

But why ? And why is set mag only supported for /foreign ?

[Ian McKerracher_1]

Wim,

You asked why SET MAGTAPE only works with foreign tapes. I have a possible explanation but it's only a guess.

By default a tape is mounted as a Files-11 ODS-2 formatted device. OpenVMS contains various ancillary control processes (ACPs) which interface between you and RMS, QIO and the Files-11 device.

A tape mounted as foreign is not a Files-11 formatted device. ACPs no longer apply and it is just you and your application, in this case BACKUP. To me this implies a greater degree of freedom, hence the ability to do things which you can't do under Files-11.

I think that this is one of those topics where we need a contribution from 'insiders' like John, Hein and Volker.

Regards,

Ian

[Wim Van den Wyngaert]

Ian,

But how do you explain that once that you used set magtape, the setting is even remembered after a dismount/nounload ?
IMO it must be possible to impement it for not foreign tapes too because it already works !

Wim@home@night

[Bojan Nemec]

Wim,

This thread seems to speak about a problem similar to yours:
http://groups.google.com/group/comp.os.vms/browse_thread/thread/ab452dcbb5e0a3f5/ddc0f89eaa624309#ddc0f89eaa624309

Seems that set mag/fast=never is remembered. This means that the tape is not able to do fast positioning and all data must be read to position to the end of file (tape) mark.

Have you done a show/device/full before and after set mag/fast=never? Is there the "device supports fastskip" phrase after the command.

Bojan

[Wim Van den Wyngaert]

Bojan,

I saw that one too.
When the tape is working correctly, the show dev xxx/fu shows "device supports fastskip (disabled)".

Wim

[Venkat_18]

Hi Wim,
Hope you have all the patches installed. I remember one of the fibre scsi (mk driver)patches addressing similar issue on Alpha OpenVMS7.3 and 7.3-1.

[Wim Van den Wyngaert]

Venkat,

I found Labadie mentioning it too. But for 7.2-2, not 7.3. Using Google, I didn't find something on the HP site for 7.3.

Wim