joel@prcrs.UUCP (Joel C. McClung) (12/04/84)
Maybe someone can enlighten me as to why this works the way it does:
My wife works on a Eunice system (version 3.2). I gave her a mag
tape with some stuff written on it in tar format (V7 tar, 1600 bpi).
She was able to extract it using tar on her Eunice machine with no
problems. She then put some things on the tape to give me, again,
using tar. She had no problem putting things ON the tape, but when
she tried to get a table of contents listing, tar complained about
the block size being zero and no TOC was generated. She recreated the
tape with tar, only this time put a blocking factor (tar cvb 20 files).
Again, there was no error, but when she tried a TOC, the same error
happened. At this point, she gave up and gave the tape back to me.
I mounted the tape on my machine and managed to generate the TOC AND
extract the tape with no problems (and yes, the files were the files
that SHE put on the tape, not the ones I put on). I don't understand..
Why is that VMS/Eunice can't read its own writing?
--
Joel C. McClung
(703) 556-2644
{seismo,allegra,ihnp4}!rlgvax!prcrs!joelsteve@drivax.UUCP (Steve Williams) (12/07/84)
> Maybe someone can enlighten me as to why this works the way it does: > > My wife works on a Eunice system (version 3.2). I gave her a mag > tape with some stuff written on it in tar format (V7 tar, 1600 bpi). > She was able to extract it using tar on her Eunice machine with no > problems. She then put some things on the tape to give me, again, > using tar. She had no problem putting things ON the tape, but when > she tried to get a table of contents listing, tar complained about > the block size being zero and no TOC was generated. She recreated the > tape with tar, only this time put a blocking factor (tar cvb 20 files). > Again, there was no error, but when she tried a TOC, the same error > happened. At this point, she gave up and gave the tape back to me. > I mounted the tape on my machine and managed to generate the TOC AND > extract the tape with no problems (and yes, the files were the files > that SHE put on the tape, not the ones I put on). I don't understand.. > > Why is that VMS/Eunice can't read its own writing? The default block size on a tape mounted with the VMS /FOREIGN switch is 512. To read a blocked tar tape, you need to set the block size to a value greater or equal to the block size on the tape. For tar b 20, the block size is 20 x 512 or 10240. Magic incantations which are known to work:: $ mount mtxx:/for/block=65534 (te16) $ mount mfxx:/for/block=65534 (tu7x) 65534 is the maximum value for the /block parameter. This allows you to read the tape even if you don't know the blocksize. -Steve Williams {ihnp4,mot,ucscc,amdahl}!drivax!steve