Unix already had the ability to mount tape devices as filesystems using the block device drivers ages ago. (V6 and probably eariler)
write your 512 byte blocks out onto the tape, mkfs (newfs now adays) your filesystem, and mount it. Not used - too slow to access because of the tape motion and unreliable, tape does not always skew up correctly as it was never designed for random access like disk, its really a linear device. Sort of write it, then read only, and rewrite the entire thing to update it. You can seek to a block, read it, seek back, write it and potentially clobber the records on the tape before or after this position by writing the new block slightly off from where it was previously written Plus - a little wear after time, stretch the tape, and your filesystem is hosed, SO NOT advised to use this way. Buy a disk and back it up to tape. > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Ken Rossman > Sent: Thursday, October 23, 2003 10:27 AM > To: [EMAIL PROTECTED] > Subject: Re: Tape Backup > > > On Thursday, October 23, 2003, at 10:18 AM, Nick Lindsell wrote: > >> The main reason is that, in order to do this you really need a > >> high-speed random access device. Tape drives are neither high > >> speed (at least not the speed you really need) nor are they > >> random access (they are sequential access). > >> > >> Perhaps someone has written a tape driver that will end up calling > >> me a liar on this point, but in general, tape is not the right > >> hardware paradigm to start with to make a good file system. > > > > I have seen such a thing - a friend of mine (Gary Howland, sadly > > deceased) wrote such a driver. It worked well enough to play Doom > > off it. :) > > You see? In the world of Linux, I am loathe these days to ever say > that something doesn't exist or can't exist -- someone out there has > probably already written it. :-) > > > This was many years ago and was DOS only - as I recall he made a > > meta index at the front of the tape which allowed to to > seek directly > > to the block where the required file was located. > > This is (more or less) how Unix "dump" format tapes work too -- table > of contents at the head of the tape. This is a special format geared > to be able to do this. I was answering the general question > of whether > one could "mount" any arbitrary tape as a file system. Programs that > use formats like the unix "dump" format and probably the one > that does > the same for DOS, use memory as a cache for the pieces that > really need > to be more random access for any kind of performance. > > > And no, I'm not calling you a liar. > > Whew! :-) > > > -- > redhat-list mailing list > unsubscribe mailto:[EMAIL PROTECTED] > https://www.redhat.com/mailman/listinfo/redhat-list > -- redhat-list mailing list unsubscribe mailto:[EMAIL PROTECTED] https://www.redhat.com/mailman/listinfo/redhat-list
