Strange file sizes for files on tape

[Oswald Knoppers_1]

Hello,

We have a strange problem with file sizes on tape.

VMS version is V7.3-2 with VMS732_SYS V14.0 and VMS732_UPDATE V14.0.
Device used is HP Ultrium 3-SCSI.

The following backup command is used (in a loop with the symbol 'rec' holding the diskname):

$ backup/image/ignore=(label) 'rec' $2$mga0:'rec'.bck/media=compaction/verify

After this a directory of the tape looks like:

$ dir/size=all/date $2$mga0:

Directory $2$MGA0:[]

DISK001.BCK;1 161755/161755 30-JAN-2008 00:00:00.00
DISK002.BCK;1 6/6 30-JAN-2008 00:00:00.00
DISK003.BCK;1 2/2 30-JAN-2008 00:00:00.00
DISK004.BCK;1 2/2 30-JAN-2008 00:00:00.00
DISK005.BCK;1 87/87 30-JAN-2008 00:00:00.00
DISK006.BCK;1 3/3 30-JAN-2008 00:00:00.00
DISK007.BCK;1 6/6 30-JAN-2008 00:00:00.00
DISK008.BCK;1 746174/746174 30-JAN-2008 00:00:00.00
DISK020.BCK;1 179826/179826 30-JAN-2008 00:00:00.00

Total of 9 files, 1087861/1087861 blocks.

The filesizes for DISK002.BCK and DISK007.bck are way to small. Now the backup command is changed to:

$ backup/image/ignore=(label) 'rec' $2$mga0:'rec'.bck/media=compaction/block=32256/verify

(different blocksize)

The directory now looks like:

$ dir/size=all/date $2$mga0:

Directory $2$MGA0:[]

DISK001.BCK;1 39173/39173 31-JAN-2008 00:00:00.00
DISK002.BCK;1 274779/274779 31-JAN-2008 00:00:00.00
DISK003.BCK;1 2/2 31-JAN-2008 00:00:00.00
DISK004.BCK;1 2/2 31-JAN-2008 00:00:00.00
DISK005.BCK;1 22/22 31-JAN-2008 00:00:00.00
DISK006.BCK;1 2/2 31-JAN-2008 00:00:00.00
DISK007.BCK;1 540113/540113 31-JAN-2008 00:00:00.00
DISK008.BCK;1 181126/181126 31-JAN-2008 00:00:00.00
DISK020.BCK;1 43509/43509 31-JAN-2008 00:00:00.00

Total of 9 files, 1078728/1078728 blocks.

These filesizes are correct.

The strange thing is that with the first tape the savesets appear to be correct. If i do a

$ backup/list $2$mga0:disk002.bck

I see all the files in the saveset.

Anybody seen this before?

Regards,

Oswald

[Willem Grooters]

Just a guess:
Would "media=compaction" be a reason?

[Volker Halle · Accepted solution]

Oswald,

this is a known problem. It has nothing to do with compaction. This has been discussed on note EISNER::VMS 1429 some time ago:

http://eisner.decus.org/DECUServe/DECnotes/VMS/1429/SDIR.HTML

DIRECTORY (i.e. MTAACP) reads the file 'size' from the EOF1/EOV1 trailer record. BACKUP writes the no. of saveset blocks into this field in the EOF1/EOV1 records. The field is only 6 characters wide and may overflow (containing '******') causing an invalid value to be returned as the 'file size'.

If you make the backup tape blocksize smaller, you'll get fewer saveset blcoks and the number may just fit into the 6-char wide field ;-)

Volker.

[Volker Halle]

Sorry, meant to say/write:

If you make the backup tape blocksize LARGER, you'll get fewer saveset blocks and the number may just fit into the 6-char wide field.

Volker.

[Oswald Knoppers_1]

Hi Volker,

Thanks for the explanation. I already thougt this was a only cosmetic problem. But now I know there is no reason to worry.

Oswald

[John Gillings]

Oswald,

Displaying sizes in BLOCKS can be confusing. I've been looking at OpenVMS directory commands for nearly 30 years and I STILL get confused trying to convert to KB or MB! When you have variable sized blocks and pages, it just gets more confusing.

I'm not sure if it works for tapes, but maybe try SET PROCESS/UNITS=BYTES? Hopefully that will give you an "absolute" size, independent of the block size, and autoranging (KB, MB, GB) to fit in the field size.

[Guy Peleg]

If you'll change your process units to
bytes DIRECTORY will tell you the real
size of the saveset (number of blocks * block size)

I'm not sure if it was added in V7.3-2
or V8.2.

Guy Peleg
BRUDEN-OSSG

[Oswald Knoppers_1]

Setting units to bytes doesn't make a difference:

Directory $2$MGA0:[]

DISK001.BCK;1 78.98MB/78.98MB 30-JAN-2008 00:00:00.00
DISK002.BCK;1 3KB/3KB 30-JAN-2008 00:00:00.00
DISK003.BCK;1 1KB/1KB 30-JAN-2008 00:00:00.00
DISK004.BCK;1 1KB/1KB 30-JAN-2008 00:00:00.00
DISK005.BCK;1 43KB/43KB 30-JAN-2008 00:00:00.00
DISK006.BCK;1 1KB/1KB 30-JAN-2008 00:00:00.00
DISK007.BCK;1 3KB/3KB 30-JAN-2008 00:00:00.00
DISK008.BCK;1 364.34MB/364.34MB 30-JAN-2008 00:00:00.00
DISK020.BCK;1 87.80MB/87.80MB 30-JAN-2008 00:00:00.00

[Volker Halle]

Oswald,

DIRECTORY does not take into account the actual blocksize of the backup savesets on tape before V8.3. For earlier versions, you need to mount the tape using the same blocksize as your BACKUP was written with, if you want the /UNIT=BYTES displayed to match your backup saveset sizes.

And if the no. of savesets blocks exceeds 999999, it still does not work correctly.

Volker.