Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!jarthur!nntp-server.caltech.edu!gumby.cs.caltech.edu!tim From: tim@gumby.cs.caltech.edu (Timothy L. Kay) Newsgroups: comp.periphs.scsi Subject: Re: DAT versus 8mm Tape Message-ID: Date: 9 Nov 90 22:30:34 GMT References: <272DB1E1.9737@orion.oac.uci.edu> <9850005@hpcpbla.HP.COM> Sender: news@nntp-server.caltech.edu Organization: California Institute of Technology, Pasadena Lines: 88 Nntp-Posting-Host: gumby.cs.caltech.edu I just thought I'd point out that comments coming from Peter King, a Hewlett-Packard employee, are a bit biased. While such opinions are not unexpected nor unwelcomed, people who are obviously biased and comercially oriented should exercise some restraint when making comments. A nice example of such restraint is demonstrated by the people at FTP Software in the groups comp.protocols.tcp-ip. Whenever they present a feature of their software, they always give a *fair* representation of the competition. Instead, Mr. King has chosen to present HP's marketting hype. peterk@hpcpbla.HP.COM (Peter King) writes: > Both drives will support 90m DAT cassettes to increase capacity beyond > the current 1.3 GBytes (60m tape). The high performance drive uses > hardware data compression to enhance performance and capacity. Expect > to see a compression ratio in the range 2 to 4 (Typically around 2.5 > on most UN*X systems) giving a maximum capacity of 8 GBytes and a maximum > transferrate of 732 KBytes/s. (>2.5 GBytes/hour!). Wow! And if I can compress my data eight times, then I'll get a transfer rate of 1464 KB/s and a capacity of 16 GB. And if I compress my data 16 times, then I'll get a transfer rate of 2928 KB/s and a capacity of 32 GB! Zow! Unfortunately I need all the capacity I can get. I already compress my data before I put it on an Exabyte tape drive. No amount of marketing double speak is going to change the fact that the HP drive holds *two* GB data. And just how much do those extended length tapes cost? I can get an 8mm 2.3 GB tape for the Exabyte for $4.75 now, quantity one, at the store down the street. > All in a 3.5" package. And when can I get one of those drives? Maybe a year from now? And how much is it going to cost me? Remember we are talking HP pricing. Sheesh, I'm surprised the DAT drives don't have HPIB interfaces on them. I'd be willing to bet that Exabyte will produce a 3.5" form factor drive. Perhaps we'll see one before the HP drives become available. >* Industry Analysts predict a bright future for DAT. The leading analysts > seem to agree that: Have anaylysts factored in the fact that disk drives are getting *very* cheap? Very soon, 2 GB of data will be small potatoes. Many Novell networks now have well over a GB of data already. In a year, they'll have to throw out their HP drive and get something that solves their problem. I don't have much confidence in industry analysts. > DAT shipments are expected to outstrip 8mm shipments during 1991 for > the first time - with DAT forecast shipments running at around 150,000 > units during 1991 (up on around 60,000 in 1990). > Forecasts show DAT shipments running at around 1/2 million per year by > 1994 - more than double the 8mm forecast of around 200,000 units. That doesn't mean that I want one. I want the best solution, not the solution that is popular just because there is a big company behind it. (For the same reason, I would never buy an HP workstation.) >* Industry Analysts also predict that DAT is likely to be far cheaper than > 8mm - partly the result of DAT's 3.5" form factor. Smaller is cheaper? In what way? 3.5" disk drives are more expensive than 5.25" disk drives, after all. This includes both hard and floppy drives. Same for the diskettes. Small audio tape players cost more than the normal-sized ones. >* Check-out Digital Review's recent article (June 90). They look at the > issue of 8mm performance and capacity. Their results are interesting. > They show that 8mm capacity and transfer rate are significantly reduced > when short saveset sizes are used. For example: > Saveset Size 8mm Capacity > 25 MBytes 2 GBytes > 5 MBytes 1.4 GBytes > 1 MBytes 560 MBytes > And they also conclude that for savesets of less than 125 MBytes DAT > Transfer Rate is faster than 8mm. And how many people use datasets of 1 MB? You'd be better off with floppy disks. I put a tape in, I back up my system, and I am done. If I had to use a DAT, it wouldn't fit, and I'd have to come back in the middle of the night. How many statistics do I need to look at to determine which drive is right for me? Tim