ohrnb@edstip.EDS.COM (Erik Ohrnberger) (03/09/90)
Does anyone have any experience with a Perstore disk controller cards? As I understand it, Perstor has developed a method to greatly decrease the diskspace that is needed for each byte of information, thusly increasing the density, with a matching increase in throughput. What sort of controller card does it look like to the host CPU? Or does it matter? I know that other MFM controllers usually top out 5.0 Mb/sec, ESDI usually delivers 10-15Mb/sec, and SCSI between 7-15 Mb/sec. How does Perstor achieve 9 MB/sec? and how reliable are the units? (how long do they last? MTBF) Are they compatible with Xenix? Any information would be greatly appreciated, Erik. -- Erik Ohrnberger Work: uunet!edsews!edstip!ohrnb 2620 Woodchase Court Home: sharkey.mi.org!nucleus!echocen!erik (preferred) Sterling Heights, MI 48310
larry@nstar.UUCP (Larry Snyder) (03/09/90)
In article <868@edstip.EDS.COM>, ohrnb@edstip.EDS.COM (Erik Ohrnberger) writes: > > Does anyone have any experience with a Perstore disk controller > cards? > > As I understand it, Perstor has developed a method to greatly decrease > the diskspace that is needed for each byte of information, thusly > increasing the density, with a matching increase in throughput. > > What sort of controller card does it look like to the host CPU? Or > does it matter? I know that other MFM controllers usually top out > 5.0 Mb/sec, ESDI usually delivers 10-15Mb/sec, and SCSI between > 7-15 Mb/sec. How does Perstor achieve 9 MB/sec? and how reliable are > the units? (how long do they last? MTBF) Are they compatible with Xenix? > Bag of worms - stay clear of the PS16 controllers from these guys. First throughput on these boards is not much better than a "standard" controller with coretests of around 290kb/sec best. With the current crop of 1:1 MFM controllers available producing throughput in the 500kb/sec range and the 1:1 RLL in the 680kb/sec range - the thoughput is slow. No drives are certified for use with this controller. Miniscibe, Seagate, Priam - none of these companies support the use of these controllers on their products. Several vendors actually claim that pushing the drive to the limits of the Perstor controller will actually void the warranty. Several friends of mine actually had problems with the Perstor controllers actually ruining a drive. Bad sectors start showing up after anywhere from 3 - 8 months of use on a regular basis. After a time the drive refuses to boot - and has to be sent in for repair. I consider it better (for me a least) to spend more $$$ and get something that runs within specifications. -- The Northern Star Public Access Unix Site, Notre Dame, Indiana USA uucp: iuvax!ndmath!nstar!larry internet: larry@nstar USR HST 219-287-9020 * PEP 219-289-3745 * Hayes V9600 219-289-0286
pmartin@psmsd.UUCP (Paul Martin) (03/13/90)
In article <868@edstip.EDS.COM>, ohrnb@edstip.EDS.COM (Erik Ohrnberger) writes: > > Does anyone have any experience with a Perstore disk controller > cards? > I am using a Perstor with a seagate 4096 80 meg and it works great! This combination gives me approx 146 megs. The card acts like an RLL by putting 31 sectors per track as opposed to 17 with an MFM on a seagate 4096. On a 20 mhz 386 I can only use a 3:1 interleave giving me throughput of 360k a second. A standard MFM on this machine uses a 2:1 interleave getting 260k a sec transfer rate (according to spinrite). As you can see, the card is superior to a standard MFM or RLL controllers. If you are going to use Xenix, be sure to get the 16FN perstor. This is an AT style hard/floppy controller for networks. The only caution I have is make sure that your case for the drive has good ventilation. The perstor will cause your drive to get hotter than normal thus causing a failure. This is because the drive spins faster under the perstor. I ran into this problem after having my drive fail. I moved it to an external case and it has work flawlessly ever since. My mini tower case has a poor design for allowing good circulation of cool air. I also have a full complement of boards and memory. A friend of mine is using 2 perstor controllers (1 in an AT and the other in a 386) with 2 seagate 4096 drives hanging off of each controller. He has never had a problem, and he bought his first perstor over 2 years ago. Also be aware that the controller is not an MFM or an RLL so programs like the new spinrite II don't like it. This is the only package that I know of that doesn't like the perstor. You can even low level format with disk manager when using a perstor. I am running both Xenix/386 and dos 3.3 with no problems at all. > 7-15 Mb/sec. How does Perstor achieve 9 MB/sec? and how reliable are I guess you would need a 33mhz or faster machine to be able to use 1:1 interleave. I for one have never seen a perstor do 9mb/sec. I hope this helps! -- +--------[ Paul Martin at P.S.M. Software Development ]--------+ | Smart: pmartin@psmsd.UUCP | "Yes I am serious, and don't | | Dumb: ...uccba!psmsd!pmartin | call me Shirley!" | +-------------------------------+------------------------------+
davidsen@sixhub.UUCP (Wm E. Davidsen Jr) (03/14/90)
In article <24@psmsd.UUCP> pmartin@psmsd.UUCP (Paul Martin) writes: | The only caution I | have is make sure that your case for the drive has good ventilation. | The perstor will cause your drive to get hotter than normal thus causing | a failure. This is because the drive spins faster under the perstor. Trust me, that's not how it works. Any form of RLL does not "make the drive spin faster" not does it "put the bits closer together." It gets compression by putting the bits farther apart and measuring the distance between them more closely. A drive which is marginal MFM may be unusable RLL when it gets a little hotter than normal, but NOT because it's spinning faster. The drive spins even with no controller at all. -- bill davidsen - davidsen@sixhub.uucp (uunet!crdgw1!sixhub!davidsen) sysop *IX BBS and Public Access UNIX moderator of comp.binaries.ibm.pc "Getting old is bad, but it beats the hell out of the alternative" -anon
larry@nstar.UUCP (Larry Snyder) (03/14/90)
In article <614@sixhub.UUCP>, davidsen@sixhub.UUCP (Wm E. Davidsen Jr) writes: > > Trust me, that's not how it works. Any form of RLL does not "make the > drive spin faster" not does it "put the bits closer together." It gets > compression by putting the bits farther apart and measuring the distance > between them more closely. > > A drive which is marginal MFM may be unusable RLL when it gets a > little hotter than normal, but NOT because it's spinning faster. The > drive spins even with no controller at all. A couple of months ago I added another controller (1542) and a large SCSI drive to my existing controller/drive combination - and like most of the midwest - we have been experiencing a "heat wave". Along with this heat (in the 90's in the computer room) read errors started appearing on the SCSI drive - and after removing the cover off the box the SCSI drive is too hot to touch. With the 50 conductor ribbon cable it's hard to keep from blocking the air flow into the power supply for the fan to shove out - but I tried :). I also replaced the fan in the PS with one that moves more air - and likewise placed a fan in the front of the machine which is sucking air in and blowing in over the boards in the expansion slots. Reference the perstor boards - I have heard many stories of them actually destroying drives by pushing the electronics beyond specs. Miniscribe, Seagate, CDC - none of the vendors certify their products for use with the Perstor cards - and as a matter of fact, the Perstor products actually decrease the transfer rate (matched against a 1:1 MFM or RLL controller) with data throughput running around 300 kb/sec. If you value your data and hardware - run them with approved controllers. - -- The Northern Star Public Access Unix Site, Notre Dame, Indiana USA uucp: iuvax!ndmath!nstar!larry internet: larry@nstar USR HST 219-287-9020 * PEP 219-289-3745 * Hayes V9600 219-289-0286
jackv@turnkey.TCC.COM (Jack F. Vogel) (03/14/90)
In article <24@psmsd.UUCP> pmartin@psmsd.UUCP (Paul Martin) writes: >The perstor will cause your drive to get hotter than normal thus causing >a failure. This is because the drive spins faster under the perstor. Huh??? You been smoking that Perstor literature or something :-}? A controller has nothing to do with the rate at which a drive spins!! That is a factor of the damn motor in the disk drive. The only reason I can see that a controller would cause the drive to be hot is how much work it gives the heads. Disclaimer: I speak for me not for LCC or IBM -- Jack F. Vogel jackv@seas.ucla.edu AIX Technical Support - or - Locus Computing Corp. jackv@ifs.umich.edu
dpi@loft386.UUCP (Doug Ingraham) (03/15/90)
In article <24@psmsd.UUCP>, pmartin@psmsd.UUCP (Paul Martin) writes: > In article <868@edstip.EDS.COM>, ohrnb@edstip.EDS.COM (Erik Ohrnberger) writes: > > > > Does anyone have any experience with a Perstore disk controller > > cards? > > > > The perstor will cause your drive to get hotter than normal thus causing > a failure. This is because the drive spins faster under the perstor. Nonsense! There is no command that can be given to a drive by the controller that will cause it to spin faster. > I ran into this problem after having my drive fail. I moved it to an > external case and it has work flawlessly ever since. My mini tower case > has a poor design for allowing good circulation of cool air. I also > have a full complement of boards and memory. The poor circulation and overloaded ventilation system was probably the actual cause of failure. > Also be aware that the controller is not an MFM or an RLL so programs > like the new spinrite II don't like it. This is the only package that > I know of that doesn't like the perstor. You can even low level format > with disk manager when using a perstor. I am running both Xenix/386 > and dos 3.3 with no problems at all. Speedstore doesn't much like it either. We tried it on lots of different drives and decided that though it worked, it worked poorly. The slow performance was probably due to the ecc being overworked. Perstore claims a proprietary encoding system that doesn't exceed the manufacturers specifications. > > 7-15 Mb/sec. How does Perstor achieve 9 MB/sec? and how reliable are The 1 sector burst rate is 9mb/sec just as its 7.5 mb/sec for RLL and 5mb/sec on MFM. There would have to be a track buffer on the controller that could hold a whole track of data to allow 1-1 interleave. We were never certain that the controller we had was working properly. We found that the data retention would vary with temperature a lot worse than with MFM. The other thing we had trouble with was the quality of the software provided by perstore for formatting and such. This stuff was clearly pre-release stuff that I wouldn't have let off my computer or even shown to anyone if I had written it. Maybe they have improved the product, but I would get one of these only with a no questions asked return policy. -- Doug Ingraham (SysAdmin) Lofty Pursuits (Public Access for Rapid City SD USA) uunet!loft386!dpi
pmartin@psmsd.UUCP (Paul Martin) (03/19/90)
In article <614@sixhub.UUCP>, davidsen@sixhub.UUCP (Wm E. Davidsen Jr) writes: > In article <24@psmsd.UUCP> pmartin@psmsd.UUCP (Paul Martin) writes: > | The only caution I > | have is make sure that your case for the drive has good ventilation. > | The perstor will cause your drive to get hotter than normal thus causing > | a failure. This is because the drive spins faster under the perstor. > > Trust me, that's not how it works. Any form of RLL does not "make the > drive spin faster" not does it "put the bits closer together." It gets > compression by putting the bits farther apart and measuring the distance > between them more closely. > The info I got from perstor is that they DO make the drive spin faster, this info could be incorrect but I thought the controller had some control over drive speed When the drive has getting hot, it would not format under an MFM controller until it cooled down, now logic tells me that the drive was getting hotter than it's normal operating parameters. Now I ask myself how would the drive get hotter under the perstor? Also the drive would operate fine under an MFM even after it warmed up. I could be wrong about this but this is the info I got from tech support. -- +--------[ Paul Martin at P.S.M. Software Development ]--------+ | Smart: pmartin@psmsd.UUCP | "Yes I am serious, and don't | | Dumb: ...uccba!psmsd!pmartin | call me Shirley!" | +-------------------------------+------------------------------+