carlo@zebra.cvs.rochester.edu (Carlo Tiana) (11/15/89)
There seems to be some confusion (at least in my mind and that of a few others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access or 12ms? The MacLand ad in the Dec 89 issue of MacUser says 19ms, while MacWeek's M.O. section has an ad by MacTel Technology Corp. listing them at 12ms. I have seen both figures in other places also, but have no references. Does anyone know what the story is? Thanks, Carlo. carlo@cvs.rochester.edu carlo@cvs.rochester.edu "Oh shit, not /dev/null!!!"
jeff@eniac.seas.upenn.edu (Jeffrey M White) (11/15/89)
In article <4050@ur-cc.UUCP> carlo@cvs.rochester.edu (Carlo Tiana) writes: >There seems to be some confusion (at least in my mind and that of a few >others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access >or 12ms? The MacLand ad in the Dec 89 issue of MacUser says 19ms, while >MacWeek's M.O. section has an ad by MacTel Technology Corp. listing them at >12ms. I have seen both figures in other places also, but have no >references. Does anyone know what the story is? Quantum drives have a 'real' access time of 19ms. However, most of them have a 64k cache chip built into them, which I guess in the standard seek test reduces this time to 12ms (often quoted as 'effective' access time). Jeff White University of Pennsylvania jeff@eniac.seas.upenn.edu
bmug@garnet.berkeley.edu (BMUG) (11/15/89)
In article <4050@ur-cc.UUCP> carlo@cvs.rochester.edu (Carlo Tiana) writes: >There seems to be some confusion (at least in my mind and that of a few >others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access >or 12ms? The ACTUAL average access speed of the Quantum 40/80/105 drives is 19 ms. However, Quantum has a 64k cache on the drive which, when enabled, lowers the access time to an optimum 12 ms. Anyone know if that 12 ms is constant, or does it depend on how data is stored, the kind of demands applications (i.e., database vs. word processor) make on it, etc? John Heckendorn /\ BMUG ARPA: bmug@garnet.berkeley.EDU A__A 1442A Walnut St., #62 BITNET: bmug@ucbgarne |()| Berkeley, CA 94709 Phone: (415) 549-2684 | |
stevem@hpvcfs1.HP.COM (Steve Miller) (11/16/89)
<Question as to what the seek time for a Quantum 105 is: 12 or 19 ms> The Quantum 105 as well as the entire Pro-Drive series from Quantum have a raw seek time averaging 19 ms. However, they have a built in caching scheme which lowers the average seek time. The actual average seek time is being advertised by Quantum's marketing department as 12 ms, although I talked to an engineer at Quantum who says that the actual number is not well understood because it is highly dependent on actual usage. The size of the cache is either 16K or 64K, I can't remember which. Steven Miller Vancouver Division Hewlett Packard
ieee@smu.uucp (IEEE group account) (11/16/89)
In article <4050@ur-cc.UUCP> carlo@cvs.rochester.edu (Carlo Tiana) writes: >There seems to be some confusion (at least in my mind and that of a few >others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access >or 12ms? The MacLand ad in the Dec 89 issue of MacUser says 19ms, while I think the 12ms is the best case with their cache. -Fred _______________________________________________________________________________ - Fred Hollander | AppleLink: F.Hollander - - President | CIS: 72077,3544 - - Software Innovations, Inc. | Internet: f.hollander@applelink.apple.com - - - - SMU is not responsible for the content of this posting. - _______________________________________________________________________________
logic@wet.UUCP (Henry Kwan) (11/16/89)
In article <4050@ur-cc.UUCP> carlo@cvs.rochester.edu (Carlo Tiana) writes: >There seems to be some confusion (at least in my mind and that of a few >others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access >or 12ms? The MacLand ad in the Dec 89 issue of MacUser says 19ms, while >MacWeek's M.O. section has an ad by MacTel Technology Corp. listing them at >12ms. I have seen both figures in other places also, but have no >references. Does anyone know what the story is? >Thanks, >Carlo. > >carlo@cvs.rochester.edu > >"Oh shit, not /dev/null!!!" This confusion is caused by the fact that Quantum hard drives have a sophisticated 64K DisCache built into the SCSI controller. This DisCache affects access speed because cache hits would tend to lower the number. Quantum officially explains it as such: On 100% random access: Seek rate is equal to 19 ms. On 50% random / 50% sequential access: Seek rate is reduced to 11.7 ms due to cache hits. So some people have gotten into the habit of refering to Quantum drives as 12 ms drives. Of course, the reason that they do it is because 12 ms is better than 19 ms anyday. A bit slippery but a defendable position. -- Henry Kwan | AppleLink: D0690 FWB, Inc. | CompuServe: 71320,1034 2040 Polk St. Ste 215 | Internet: claris!wet!logic@ames.arc.nasa.gov San Francisco, CA 94109 | UUCP: {claris,hoptoad,lamc,ucsfcca}!wet!logic
jca@pnet01.cts.com (John C. Archambeau) (11/17/89)
carlo@zebra.cvs.rochester.edu (Carlo Tiana) writes: >There seems to be some confusion (at least in my mind and that of a few >others I spoke to) about the Quantum 105Mb drives' speed. Is it 19ms access >or 12ms? The MacLand ad in the Dec 89 issue of MacUser says 19ms, while >MacWeek's M.O. section has an ad by MacTel Technology Corp. listing them at >12ms. I have seen both figures in other places also, but have no >references. Does anyone know what the story is? >Thanks, >Carlo. All Quantum 3.5" ProDrives have an average seek time of 19 ms. The only ont drive that I know of that got that fast was the units by Core which use their own proprietary controller for the IBM PC compatable market (somewhere between ST412/506 and ESDI). The data sheet for those units says 14 ms, but it was not uncommon for a Core HC 310 to get an average seek of 12 to 10 milliseconds. If you want speed and mass storage, get an Imprimis (CDC MacWren) or a Maxtor unit. In fact, MicroNet has put a freeze on purchasing ALL Quantum drives until the problem is 100% fixed. The drive mechanism problem on the P-40S and P-80S has replicated itself on the P-105S, but to a much lesser extent, so before the 105's got really bad, MicroNet just basically told Quantum "call us when it's fixed, we're not selling anything made by you until you do." I'm hoping that the 105's we have in house don't go kaput, if they do. I'm going to be very ticked off along with a few system engineers at Sun since they're used as internal drives on the SPARCstation 1's and 3/80's /*--------------------------------------------------------------------------* * Flames: /dev/null (on my Minix partition) *--------------------------------------------------------------------------* * ARPA : crash!pnet01!jca@nosc.mil * INET : jca@pnet01.cts.com * UUCP : {nosc ucsd hplabs!hd-sdd}!crash!pnet01!jca *--------------------------------------------------------------------------* * Apple Computer, Inc. is really the Anti-Christ! *--------------------------------------------------------------------------* * Note : My opinions are that...mine. My boss doesn't pay me enough to * speak in the best interests of the company (yet). *--------------------------------------------------------------------------*/