Re: Tape Volume Information Report

[Dave McKenzie <davemck@xxxxxxxxxxxxx>]

Below are the ones I know about.

--Dave

John P. Walsh wrote:
> Could someone please provide a brief description of the following columns of
> information on this report:
>  
> Recg Tech
??

> Record Length
Used for blocked-record formats for data tape files.  Save tapes (those 
written with SAVLIB, SAVOBJ, etc.) use unblocked format so Record Length 
doesn't apply, and shows as zero.

> Block Length
Maximum length of blocks written to tape (with inter-block gaps 
between).  Actual blocks may be shorter.  E.g. for save tapes with 
USEOPTBLK(*NO), block length shows 32760, but actual blocks are usually 
28762.  You can see with DMPTAP.

> File Length
Number of blocks written in the tape file (i.e. the library for SAVLIB).

> Mvol Ind
Multi-volume indicator.
CONT = file is continued on next volume (cartridge or reel).
LAST = last volume of a continued file.

> Mvol Sequence
Sequence number of volume in multi-volume file.

>  
> All the values on a report I have show a Record Length of 0000 and Block
> Length of 262144.  Should that be?  Is a certain block lenghth allocated for
> each library regardless of the space it will actually occupy?  

That's normal for save tapes when you specify USEOPTBLK(*YES) on the 
SAV- command.

262144 (256K) is the typical optimum block length.  In theory, it can be 
different for different models of tape drive, but 262144 is the only 
length I've seen.  Old, small tape devices don't have the optimum block 
capability -- for them Block Length is always 32760.

These figures all refer to un-compressed data.  The tape device usually 
does hardware compression so less data is actually written to tape.

>  
> John P. Walsh
> Home: (941) 776-1758 Cell: (727) 543-8561
> jwalsh23@xxxxxxxxxxxxxxx
>