MATLEVAN@EKU.BITNET (Jerry LeVan) (03/25/90)
Hello, Has anyone out there used the Apple Tape Cartridge to store multiple tar/cpio file archives? It is clear that the "norewind" device must be used, but does the tape driver write and eof mark? Should the "mt" command be used to write eof marks after each archive? Is there any way to determine how many archives are stored on the tape... Thanks...Jerry ----------------------------------------------------------------------------- | Jerry LeVan | Phone:(606)-622-1931 | | Department of Computer Science | | | Eastern Kentucky University | Email:matlevan@eku.bitnet | | Richmond Ky 40475 | | |---------------------------------------------------------------------------| | "The series converges so slowly that it actually diverges." | -----------------------------------------------------------------------------
tody@noao.edu (Doug Tody X217) (03/26/90)
From article <AUXPOST%90032510412694@PUCC.BITNET>, by MATLEVAN@EKU.BITNET (Jerry LeVan): > Hello, > Has anyone out there used the Apple Tape Cartridge to store > multiple tar/cpio file archives? It is clear that the "norewind" > device must be used, but does the tape driver write and eof mark? Yes. All unix tape drivers automatically write an EOT (double tape mark) when a file opened for writing is subsequently closed. If closed no-rewind, the tape is left positioned between the file marks and the next file will overwrite the second tape mark, giving you an EOF between the files (those are the standard semantics, the details of what actually goes on at the physical level with the Apple tape may differ, but I doubt that it matters). > Should the "mt" command be used to write eof marks after each > archive? No. That would probably give you an EOT, making the tape difficult to read... Just tar to the new-rewind device, and tar again for each successive file. Very easy. > Is there any way to determine how many archives are stored > on the tape... It is not hard to write a program to count files and records on a tape, but I don't know of anything in A/UX or standard unix. -- Doug Tody, National Optical Astronomy Observatories, Tucson AZ, 602-325-9217 UUCP: {arizona,decvax,ncar}!noao!tody or uunet!noao.edu!tody Internet: tody@noao.edu SPAN/HEPNET: NOAO::TODY (NOAO=5355)
rick@Apple.COM (Rick Auricchio) (03/27/90)
In article <AUXPOST%90032510412694@PUCC.BITNET> MATLEVAN@EKU.BITNET (Jerry LeVan) writes: >Hello, >Has anyone out there used the Apple Tape Cartridge to store >multiple tar/cpio file archives? It is clear that the "norewind" >device must be used, but does the tape driver write and eof mark? >Should the "mt" command be used to write eof marks after each >archive? The driver correctly writes TWO EOF marks, then backspaces between them, so that if you continue with another file you get the proper single EOF between files, and two at the end of all files. Exact emulation of 9track tape. Is there any way to determine how many archives are stored >on the tape... Keep doing "mt fsf 1" commands (on the norewind device) and "mt status" commands and watch for the block to bump by only one block (which means you hit another eof instantly). Or, simply run dd >/dev/null, counting the dd commands until one returns "0+0 blocks in". That last one is hitting an instant EOF at the double EOF. -- -- Rick Auricchio, Apple Computer Inc, 20525 Mariani Av MS 58A Cupertino CA 95014 sun!apple!rick OR rick@apple.COM Mooney N894AR (408) 974-4227 Never eat prunes when you're famished. My opinion is my own. My employer? They use a windsock and a fire extinguisher.
name@portia.Stanford.EDU (tony cooper) (03/27/90)
In article <1990Mar26.062901.8016@noao.edu> tody@noao.edu (Doug Tody X217) writes: >> Hello, >> Has anyone out there used the Apple Tape Cartridge to store >> multiple tar/cpio file archives? It is clear that the "norewind" >> device must be used, but does the tape driver write and eof mark? > >Yes. All unix tape drivers automatically write an EOT (double tape mark) >when a file opened for writing is subsequently closed. If closed no-rewind, >the tape is left positioned between the file marks and the next file will >overwrite the second tape mark, giving you an EOF between the files (those I don't know if Tody is using logic to say that the Apple tc tape driver write EOT's. But the premise is wrong. It is not true that all unix tape drivers behave as described. To write two tape marks and to position the tape between filemarks requires that the tape drive can backspace. The Apple tape drive can backspace and uses this method for EOT's. But not all drives can backspace. The TEAC drives cannot and so they use a different mechanism to recognize the end of tape. Tony Cooper tony@popserver.stanford.edu