sissi@IGOR.TAMRI.COM (Sissi Tchehrazi) (02/13/91)
Can someone explain this phenomenon to me please? mt fsf (advances my 8mm tape one file) at this point I will like to write a new file bru -cvf /dev/nrtape (8mm is linked to tape size=0K ..) result: bru: Warrning Input/Output Error bru: load volume 1 and enter .... but if at this point I do a: mt feom (which is not what I really want) then bru -cvf /dev/nrtape works fine!!! Why this behavior, and how can I simply advance a file and write a new file (without going to EOD) to my 8mm tape using bru? Thanks in advance. ========================================================================== Sissi Tchehrazi Internet: sissi@tamri.com Toshiba America MRI Phone: (415) 737-6620 So. San Francisco, CA
olson@anchor.esd.sgi.com (Dave Olson) (02/13/91)
In <9102122035.AA22599@igor.tamri.com> sissi@IGOR.TAMRI.COM (Sissi Tchehrazi) writes: | | Can someone explain this phenomenon to me please? | | | mt fsf (advances my 8mm tape one file) | | at this point I will like to write a new file | | bru -cvf /dev/nrtape (8mm is linked to tape size=0K ..) | result: | bru: Warrning Input/Output Error | bru: load volume 1 and enter .... | | but if at this point I do a: | | mt feom (which is not what I really want) | | then | | bru -cvf /dev/nrtape works fine!!! | | Why this behavior, and how can I simply advance a file and write a | new file (without going to EOD) to my 8mm tape using bru? Because while 8mm drives can append at any FM, it has to be on the BOT side of the FM. So you have to do mt fsf 1, mt bsf 1, if I remember correctly. Remember that the new EOD is where you stop writing, you can't just overwrite part of the data. mt feom takes care of getting you on the correct side of the FM; I'm not sure right now if we made the append at any filemark work in 3.2 or 3.3, or perhaps not till 4.0 -- Dave Olson Life would be so much easier if we could just look at the source code.
dhinds@elaine21.stanford.edu (David Hinds) (02/13/91)
In article <1991Feb13.043605.17095@odin.corp.sgi.com> olson@anchor.esd.sgi.com (Dave Olson) writes: >In <9102122035.AA22599@igor.tamri.com> sissi@IGOR.TAMRI.COM (Sissi Tchehrazi) writes: >| >| mt fsf (advances my 8mm tape one file) >| at this point I will like to write a new file >| bru -cvf /dev/nrtape (8mm is linked to tape size=0K ..) >| result: >| bru: Warrning Input/Output Error >| bru: load volume 1 and enter .... > >Because while 8mm drives can append at any FM, it has to be on the >BOT side of the FM. So you have to do mt fsf 1, mt bsf 1, if I >remember correctly. Remember that the new EOD is where you stop >writing, you can't just overwrite part of the data. > >mt feom takes care of getting you on the correct side of the FM; >I'm not sure right now if we made the append at any filemark work in 3.2 or >3.3, or perhaps not till 4.0 I don't think this is right. I'm pretty sure the 8mm drives can't back up except when rewinding, so "mt bsf 1" won't work. "mt feom" puts you at EOD, which has to be on the far side of whatever other marks are put down at the end of a file. -David Hinds dhinds@cb-iris.stanford.edu
olson@anchor.esd.sgi.com (Dave Olson) (02/14/91)
In <1991Feb13.061746.21283@portia.Stanford.EDU> dhinds@elaine21.stanford.edu (David Hinds) writes: | In article <1991Feb13.043605.17095@odin.corp.sgi.com> olson@anchor.esd.sgi.com (Dave Olson) writes: | >In <9102122035.AA22599@igor.tamri.com> sissi@IGOR.TAMRI.COM (Sissi Tchehrazi) writes: | >| | >| mt fsf (advances my 8mm tape one file) | >| at this point I will like to write a new file | >| bru -cvf /dev/nrtape (8mm is linked to tape size=0K ..) | >| result: | >| bru: Warrning Input/Output Error | >| bru: load volume 1 and enter .... | > | >Because while 8mm drives can append at any FM, it has to be on the | >BOT side of the FM. So you have to do mt fsf 1, mt bsf 1, if I | >remember correctly. Remember that the new EOD is where you stop | >writing, you can't just overwrite part of the data. | > | >mt feom takes care of getting you on the correct side of the FM; | >I'm not sure right now if we made the append at any filemark work in 3.2 or | >3.3, or perhaps not till 4.0 | | I don't think this is right. I'm pretty sure the 8mm drives can't back | up except when rewinding, so "mt bsf 1" won't work. "mt feom" puts you at | EOD, which has to be on the far side of whatever other marks are put down | at the end of a file. Nope; I have no idea where you got the idea that 8mm drives can't bsf or bsr, but having written the driver, tested it, and used it numerous times, I can assure you that it can do these things! The 8mm drive doesn't support the direct space to end of media command either, unlike every other scsi tape drive we use, so even that has to be faked. I re-checked the driver and the Exabyte manual, and my original statement about being to append at arbitrary filemarks should be correct for 3.3 and later. I didn't check 3.2. Note that this is NOT enough to allow 'tar rvf files' to work, since that requires overwriting data blocks also, which isn't supported by Exabyte. -- Dave Olson Life would be so much easier if we could just look at the source code.
jeremy@perf2.asd.sgi.com (Jeremy Higdon) (02/14/91)
In article <9102122035.AA22599@igor.tamri.com>, sissi@IGOR.TAMRI.COM (Sissi Tchehrazi) writes: > > > Can someone explain this phenomenon to me please? > > > mt fsf (advances my 8mm tape one file) > > at this point I will like to write a new file > > bru -cvf /dev/nrtape (8mm is linked to tape size=0K ..) > result: > bru: Warrning Input/Output Error > bru: load volume 1 and enter .... > > but if at this point I do a: > > mt feom (which is not what I really want) > > then > > bru -cvf /dev/nrtape works fine!!! > > Why this behavior, and how can I simply advance a file and write a > new file (without going to EOD) to my 8mm tape using bru? The 8mm distinguishes between the top and bottom of a filemark. Now the 8mm can write from BOT, bottom of filemark, and EOD. So to do what you want, mt fsf mt bsf mt weof (Assuming you still want separate files) bru -cvf ... Realize that all data after a write is generally lost (if you're lucky, you can still get at part of it on the 8mm, but it is unpredictable).