Invalid block size error with vmsbackup

kaplan71 · 03-23-2017, 10:07 AM

Hello --

We are trying to recover data from older VMS backups using the 4.1 release of the vmsbackup utility. The archives were sent to us in zip format, and an example of one is the following:

Quote:

170312_SAMPLES.zip

Using the unzip command, the contents of were extracted into the directories shown below:

Quote:

170312-001-002
170312-001-003
170312-001-004
170312-001-005
170312-001-006
170312-001-007
170312-001-008
170312-001-009
170312-001-010

A sample of the files in the extracted folders is as follows:

Quote:

SFONGSP1_SL.BCK
SFONGVT1_SL.BCK

An example of the syntax that is being used to extract from the bck files is the following:

Code:

/usr/local/bin/vmsbackup -x -d -f SFONGSP1_SL.BCK

The files do not get extracted, and the error message that we are getting is as follows:

Quote:

Snark: Invalid block size

Does anyone have any ideas on this?

TB0ne · 03-23-2017, 12:17 PM

Quote:

Originally Posted by kaplan71

Hello --
We are trying to recover data from older VMS backups using the 4.1 release of the vmsbackup utility. The archives were sent to us in zip format, and an example of one is the following:

Using the unzip command, the contents of were extracted into the directories shown below: A sample of the files in the extracted folders is as follows: An example of the syntax that is being used to extract from the bck files is the following:

Code:

/usr/local/bin/vmsbackup -x -d -f SFONGSP1_SL.BCK

The files do not get extracted, and the error message that we are getting is as follows:

Code:

Snark: Invalid block size

Does anyone have any ideas on this?

When dealing with backup files, the first and most obvious question is, "what was the program that created these files?" Secondly...you didn't post the whole error message, did you? Because typically after the "Snark" message, it will tell you something like " - expected: xxx got: yyy" after it.

The -f flag is for specifying the device, not the file. From the man page:

Code:

-f             Use  the  next  argument in the command line as the tape device to be used, rather
	       than the default.

	       If vmsbackup is compiled with the remote tape option and the  file  name  has  the
	       form  system[.user]:/dev/???   vmsbackup  will  use the tape drive /dev/??? on the
	       remote system system, via rsh(1), and rmt(8).  The optional user  portion  of  the
	       pathname  specifies the login name to use on the remote system.	If it is not sup-
	       plied, the current user's login name will be used.  In all  the	cases,	the  user
	       must  have the appropriate permissions on the remote machine, in order to use this
	       facility.  The default is /dev/rmt8 (drive 0, raw mode, 1600 bpi).  This must be a
	       raw mode tape device.

Try it without the -f. Also, you may want to use the -t option alone first, to make sure you can actually read the file.

kaplan71 · 03-23-2017, 12:48 PM

Hello --

Thank-you for your reply.

The program that created these files was an in-house application designed to run on a VAX/VMS server.
I can assure you the error message that I listed in my initial email was copied verbatum from the console window.

Per your instructions, I ran the following command syntaces:

Quote:

/usr/local/bin/vmsbackup -t -d SFONGSP1_SL.BCK
/usr/local/bin/vmsbackup -x -d SFONGSP1_SL.BCK

and in both instances the error message that I encountered is the following:

Quote:

/dev/rmt8: No such device or address

TB0ne · 03-23-2017, 01:56 PM

Quote:

Originally Posted by kaplan71

Hello
The program that created these files was an in-house application designed to run on a VAX/VMS server.

Then you need to find out how it wrote those files. Without knowing the block size/structure/etc., there's no way to guess.

Quote:

I can assure you the error message that I listed in my initial email was copied verbatum from the console window.

Then you have a special version of things that doesn't include the whole error message.

Quote:

Per your instructions, I ran the following command syntaces:

Code:

/usr/local/bin/vmsbackup -t -d SFONGSP1_SL.BCK
/usr/local/bin/vmsbackup -x -d SFONGSP1_SL.BCK

Read the man page on that command, and try to play with the options. Omit the -d, but really it is up to you to try some different things on your own as well. The -d means to create the file/directory tree structure. If it can't (the path may be VERY different), then it may error out. And have you tried specifying the path to the file, as in "./<filename>", or "/some/path/filename.bck"?

Quote:

and in both instances the error message that I encountered is the following:

Then I have no idea. The -f explicitly says it is ONLY to be used for a tape device, coupled with the fact you're getting no block-size message, would indicate something is up with vmsbackup. Since you don't say what version/distro of Linux, where you got this program or how it got installed, we can't guess.

kaplan71 · 03-23-2017, 04:10 PM

The solution to the problem was to include the following in the command syntax:

Quote:

-b 8192

TB0ne · 03-23-2017, 04:34 PM

Quote:

Originally Posted by kaplan71

The solution to the problem was to include the following in the command syntax:

So you specified the block size..excellent.