rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) (04/22/91)
I'm looking into high capacity backup drives for a system which is initially going to have a 1.2gig scsi disk on it. I discarded the idea of QIC tapes as being too slow, even though I have this sneaky feeling that if I get tapes in the mail from people, they'll be qic format. That leads 4 and 8mm DAT tapes, I believe. My limited talks with vendors have gotten me the following bits of (what may be) information: - Exabyte is the sole manufacturer of 8mm tape drives. They have higher bandwidth and capacity than 4mm tapes. They may do a better job of read/write error handling. - Many (14 or so?) companies make 4mm DAT drives. Someone at Exabyte said that there appeared to be some compatability problems among tapes written by different firms' drives. - Exabyte claims to have better in-field reliaility. The 4mm pundits claim fewer moving parts, ergo better theoretical reliability. However, since they have only been out for a year or so(?), in-field reliabilty cannot claim to compete with Exabyte. I would appreciate hearing from anyone with experience in this area, and recommendations, etc. I was almost ready to go with Exabyte, but am wondering if the 4mm stuff is going to take over, leaving me with what is essentially a very expensive paper tape drive (in terms of being able to read other's media). Thanks for your time. By the way, I received two responses on a previous posting about R Squared and inexpensive Fujitsu drives, which were basically favorable - their prices are the lowest I've encountered, and I'll probably order my Fujitsu drive from them. Ditto the tape, if I can decode on format... Robert Bernecky rbe@yrloc.ipsa.reuter.com bernecky@itrchq.itrc.on.ca Snake Island Research Inc (416) 368-6944 FAX: (416) 360-4694 18 Fifth Street, Ward's Island Toronto, Ontario M5J 2B9 Canada
cpcahil@virtech.uucp (Conor P. Cahill) (04/23/91)
rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) writes: >I'm looking into high capacity backup drives for a system which is >initially going to have a 1.2gig scsi disk on it. I discarded the For performance you might want to consider a pair of 600 MB drives or 4 330 mb drives. (Yes, I know the cost goes up as you do this, but you sound like the system is going to be a high cost item and the extra cost used to get this gain in performance may be minimal when compared to the overall system cost). >idea of QIC tapes as being too slow, even though I have this sneaky >feeling that if I get tapes in the mail from people, they'll be qic format. If you want a high capacity and high speed backup drive both 4 & 8mm will do. If you want to be able to share data via the tapes, you will have to get a QIC drive because it is the prevalent format and because most people can't afford the extra cost of the high capacity tapes. >- Exabyte is the sole manufacturer of 8mm tape drives. They have > higher bandwidth and capacity than 4mm tapes. They may do a better > job of read/write error handling. I find this hard to believe, especially when you pick up a copy of a unix rag and find advertisements from companies like media cybernetics who have thier own 8mm product. >- Many (14 or so?) companies make 4mm DAT drives. Someone at Exabyte > said that there appeared to be some compatability problems among > tapes written by different firms' drives. I would take this with a grain of salt, comming from Exabyte. The only 4mm drives I've used are HP's, so I don't have any experience with compatibility. >- Exabyte claims to have better in-field reliaility. The 4mm pundits > claim fewer moving parts, ergo better theoretical reliability. However, > since they have only been out for a year or so(?), in-field reliabilty > cannot claim to compete with Exabyte. Sounds like marketing hype to me. >By the way, I received two responses on a previous posting about >R Squared and inexpensive Fujitsu drives, which were basically >favorable - their prices are the lowest I've encountered, and I'll >probably order my Fujitsu drive from them. Ditto the tape, if I can >decode on format... Why not post the info. -- Conor P. Cahill (703)430-9247 Virtual Technologies, Inc. uunet!virtech!cpcahil 46030 Manekin Plaza, Suite 160 Sterling, VA 22170
kdenning@pcserver2.naitc.com (Karl Denninger) (04/24/91)
In article <1991Apr23.123631.6147@virtech.uucp> cpcahil@virtech.uucp (Conor P. Cahill) writes: >rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) writes: >>- Exabyte is the sole manufacturer of 8mm tape drives. They have >> higher bandwidth and capacity than 4mm tapes. They may do a better >> job of read/write error handling. > >I find this hard to believe, especially when you pick up a copy of a >unix rag and find advertisements from companies like media cybernetics >who have thier own 8mm product. Actually, Sony makes the mechanisms. Sony IS the only 8mm transport manufacturer. Check the inside of one of those CY8200's sometime -- it's a Sony transport. Ever notice how all the 2GB drives all appear to look exactly the same from the front....... I'd love to see some other company in there, but there may very well be a patent consideration operative here. -- Karl Denninger - AC Nielsen, Bannockburn IL (708) 317-3285 kdenning@nis.naitc.com "The most dangerous command on any computer is the carriage return." Disclaimer: The opinions here are solely mine and may or may not reflect those of the company.
richard@pegasus.com (Richard Foulk) (04/25/91)
>If you want a high capacity and high speed backup drive both 4 & 8mm will do. > >If you want to be able to share data via the tapes, you will have to get >a QIC drive because it is the prevalent format and because most people can't >afford the extra cost of the high capacity tapes. Change that to say "most can't afford the high capacity tape DRIVES". The 8mm tapes themselves are much less expensive than QIC tapes. You can buy them at the drug stores around here for $7. In case-quantities they're even cheaper. I think this puts the cost-per-megabyte with 8mm tapes at about 1/30th that of QIC tapes. Don't buy certified data tapes -- they're a lot more money for the same item. Regular Sony video tapes perform just as well. El-cheapo tapes also work fine, though the recoverable errors count becomes non-zero. (Error correction capabilities on the Exabyte drives are very impressive and seldom used -- at least with Sony tapes.) If you expect to use a fair number of tapes over the next year or so the Exabyte drive could ultimately save you money. >>- Exabyte is the sole manufacturer of 8mm tape drives. They have >> higher bandwidth and capacity than 4mm tapes. They may do a better >> job of read/write error handling. > >I find this hard to believe, especially when you pick up a copy of a >unix rag and find advertisements from companies like media cybernetics >who have thier own 8mm product. All the 8mm vendors buy from Exabyte, a subsidiary (or something like that) of Sony. Note that 4mm drives are much newer, slower, hold half as much, use more expensive tapes, and (from my reading of the specs and technique) don't use nearly as good an error recovery approach. The 4mm guys are now boasting numbers that compete better with Exabytes in speed and capacity -- they gain this new level of performance by adding compression to the interface :-(. This means the capacity varies according to your data, and amounts to a net loss if the files you're writing are already compressed. (They often mention the compression in small print, if at all.) Check the sun-spots mailing list archives of a year or two ago for a lot more insight into the development and ins and outs of the Exabyte drive. BTW: as far as data-sharing goes, I think UUNET makes their archives available via 8mm tape. -- Richard Foulk richard@pegasus.com
rbe@yrloc.ipsa.reuter.COM (Robert Bernecky) (04/25/91)
Conor Cahill asks "why not post the (price) info?" OK, here is what I got from R Squared in terms of a quote: 1.2gb Fuijtsu M2266a scsi disk drive Exabyte EXB-8200 8mm tape backup drive 2 holer cabinet for above All cables and terminators; drives mounted in cabinet. All docn from manufacturer; "software drivers are included with the controller". $4755.00 usd adaptec 1542b controller: Add $299.00 4holer cabinet instead of 2 -holer: Add $400.00 usd delivery 3-5 days; dob englewood Colorado R Squared is at (303) 799-9292, or (800) 777-3478 I'm still haggling with domestic vendors here, so have not ordered anything yet. Bob Robert Bernecky rbe@yrloc.ipsa.reuter.com bernecky@itrchq.itrc.on.ca Snake Island Research Inc (416) 368-6944 FAX: (416) 360-4694 18 Fifth Street, Ward's Island Toronto, Ontario M5J 2B9 Canada
rcd@ico.isc.com (Dick Dunn) (04/26/91)
richard@pegasus.com (Richard Foulk) writes: (regarding 8mm tapes) > Don't buy certified data tapes -- they're a lot more money for the same > item. Regular Sony video tapes perform just as well... They're not (quite) the same item. The data-grade tapes come out of the same manufacturing process as the video tapes, so in that sense they're the same--but the data-grade tapes are selected. A tape that fails the data- grade test becomes a video tape. Still, the video tape is acceptable. You'll get more errors--normally all recoverable, but since a bad spot causes a skip on the tape, you get somewhat reduced capacity and slower overall data rate. However, it's about a 2:1 difference in price of tapes, while the difference in performance/capacity is much less, so the video tapes are still a reasonable deal. I think I'd use data-grade tapes for serious archival. > (Error correction capabilities on the Exabyte drives are very > impressive and seldom used -- at least with Sony tapes.) Yes and no...they *are* impressive, but they do get used fairly often. You don't normally see the error correction done with ECC, but you will see the bad-spot skipping. The error correction has to be good because it does get used. > >>- Exabyte is the sole manufacturer of 8mm tape drives. They have > >> higher bandwidth and capacity than 4mm tapes. They may do a better > >> job of read/write error handling. > > > >I find this hard to believe, especially when you pick up a copy of a > >unix rag and find advertisements from companies like media cybernetics > >who have thier own 8mm product. > > All the 8mm vendors buy from Exabyte, a subsidiary (or something like that) > of Sony. Ack! No! Yes, all the 8mm drives are ultimately based on Exabyte's products...but Exabyte is NOT a subsidiary of Sony (and they would probably not like it much if you said that!). They buy the drive mechanism from Sony and add their own electronics and firmware. -- Dick Dunn rcd@ico.isc.com -or- ico!rcd Boulder, CO (303)449-2870 ...While you were reading this, Motif grew by another kilobyte.
peter@ficc.ferranti.com (Peter da Silva) (04/26/91)
In article <1991Apr25.015612.1847@pegasus.com> richard@pegasus.com (Richard Foulk) writes: > Note that 4mm drives are much newer, slower, hold half as much, use more > expensive tapes, and (from my reading of the specs and technique) don't > use nearly as good an error recovery approach. 4mm are slower than 8mm *if you're streaming*. 4mm hold less than 8mm *if you can keep streaming*. But because the 4mm accelerates and decelerates more quickly, seek time is lower and the gaps when you lose streaming are a lot smaller. Keeping these buggers streaming is a major problem, in general, unless you work your butts off or just have small, fast drives. So, 8mms advantage in capacity and speed is not quite what it's cracked up to be. -- Peter da Silva. `-_-' peter@ferranti.com +1 713 274 5180. 'U` "Have you hugged your wolf today?"
richard@pegasus.com (Richard Foulk) (05/02/91)
> >(regarding 8mm tapes) >> Don't buy certified data tapes -- they're a lot more money for the same >> item. Regular Sony video tapes perform just as well... > >They're not (quite) the same item. The data-grade tapes come out of the >same manufacturing process as the video tapes, so in that sense they're the >same--but the data-grade tapes are selected. A tape that fails the data- >grade test becomes a video tape. [...] The tapes in question are (as far as I'm aware) made by one outfit (Sony) for video use, and verified and sold as data tapes by another outfit. The data tape market is so minuscule compared to the video tape market that this graded-product approach just doesn't seem likely at the manufacturing level (if that's what was meant). > [...] Still, the video tape is acceptable. >You'll get more errors--normally all recoverable, but since a bad spot >causes a skip on the tape, you get somewhat reduced capacity and slower >overall data rate. From some testing reported in Sun-spots, over a period of a couple of years, the general consensus was that standard Sony video tapes suffered no disadvantage to the "data grade" tapes. (The Exabyte drive counts the number of errors it corrects, given support in the device driver it can be accessed by the user -- thus you can do your own tape grading.) >> (Error correction capabilities on the Exabyte drives are very >> impressive and seldom used -- at least with Sony tapes.) > >Yes and no...they *are* impressive, but they do get used fairly often. You >don't normally see the error correction done with ECC, but you will see the >bad-spot skipping. The error correction has to be good because it does get >used. The testing I mentioned earlier showed that many Sony tapes were error-free. And that most had less than a handful of errors. (This is recollection from a while back -- I'll go find the data and post it when I get a chance.) I know of several large computing centers that buy video-grade Sony tapes by the case, and consider the "data grade" tapes as nothing but a ripoff directed at the uninformed. If you must, get a device driver that returns the error count, and do your own tape grading -- if the error count is higher than you'd like on a backup then use a fresh tape and do it again. Keep in mind that using the worst video-grade tapes available it's unlikely that you'll actually lose any data. [I have no connections with Exabyte or Sony, never have. I don't even currently have an Exabyte drive, though I wish I did. I've used them in the past and had nothing but good results.] -- Richard Foulk richard@pegasus.com