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
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