apratt@atari.UUCP (Allan Pratt) (05/02/89)
In article <4002@druwy.ATT.COM> dlm@druwy.ATT.COM (Dan Moore) writes: > in article <17646@cup.portal.com>, Xorg@cup.portal.com (Peter Ted Szymonik) says: > > And what about Seymour-Rand's VCR tape backup cartridge?? > What is so amazing about it? Companies have been selling VCR > based backup systems for years. [...] If > you use a good VCR with high quality tapes and some sort of ECC (Error > Correcting Code) they are acceptable. I'd still create 2 different > backup tapes every time I backed up (assuming the data is reasonably > important). I brought up a supermicro system in 1980 or so (I forget the manufacturer and year) from a VCR backup of the root pack, and learned a thing or two: the standard technique (at the time, at least) was to write each block several times -- up to ten -- before going on to the next block. This makes the backup slower than the nominal kbyte/sec rate, but you figure with the ECC that at least ONE of the ten block images will decode with no uncorrectable errors. ============================================ Opinions expressed above do not necessarily -- Allan Pratt, Atari Corp. reflect those of Atari Corp. or anyone else. ...ames!atari!apratt
waycott@ellymae.phx.mcd.mot.com (John Waycott) (05/03/89)
In article <1468@atari.UUCP> apratt@atari.UUCP (Allan Pratt) writes: >In article <4002@druwy.ATT.COM> dlm@druwy.ATT.COM (Dan Moore) writes: >> [...] If >> you use a good VCR with high quality tapes and some sort of ECC (Error >> Correcting Code) they are acceptable. I'd still create 2 different >> backup tapes every time I backed up (assuming the data is reasonably >> important). > >I brought up a supermicro system in 1980 or so (I forget the >manufacturer and year) from a VCR backup of the root pack, and learned a >thing or two: the standard technique (at the time, at least) was to >write each block several times -- up to ten -- before going on to the >next block. This makes the backup slower than the nominal kbyte/sec >rate, but you figure with the ECC that at least ONE of the ten block >images will decode with no uncorrectable errors. > The system you are talking about was probably an Alpha Microsystems AM-1000. It was a 68000 multi-user system with a VCR backup built in. I had one of these for several years (I sold it last year). I would imagine that VCR backup technology has improved somewhat; the AM-1000 took about 20 Minutes to backup 10 Megabytes - not blazing fast. Even so, I found it extremely reliable. I never once had a problem backing up or restoring files from tape. This was also using a vintage 1970's VCR. It appeared that it wrote 10 copies of each block on one video frame, so you got a minimum of 10 copies on the tape. If the disk drive was slow, the VCR backup hardware would just keep writing the same block (10 times/frame) on successive video frames. This huge amount of redundancy pretty much assured a clean copy, albiet slow writing. I found that the big disadvantage to VCR backup was when it came time to restore files. If I needed to load a file that was one hour into the tape, I either had to let it run for an hour or use a search feature where I manually fast-forwarded the VCR until I got close to the file I wanted. Does anyone know if the VCR backup products for the Atari let you do this? I think a VCR backup system for the Atari is a good idea. It has the advantage of large data storage (no more 57 floppy backups) and very inexpensive media. Most Atari owners probably already own a VCR, although many people would probably end up buying one for the computer instead of hauling the VCR in from the living room. -- John Waycott mcdphx!ellymae!waycott