tims@infidel.lanl.gov (Tim Sullivan) (05/17/91)
I am confused about the SCSI interface. Let me describe the problem I was trying to solve and hope that someone can explain why I was wrong. A Sun network here at the Lab needed more disk space and tape backup, so they went out and bought an external box from R-Squared that has a 1.2Gbyte hard drive and a 2.3 Gbyte Exabyte tape drive. It interfaces to a Sun throught the Sun SCSI port. No problem. Now we have an AT and a frame grabber that takes data off of a video camera. For something that we want to do, we are limited by the size of our hard disk, which coincidentally died. So we said, why don't we replace the dead MFM hard disk with a small SCSI disk and when we need to we can bring the R-Squared system over and use with the AT? A 150Mb SCSI drive might cost us $750 or so, and a SCSI controller can be found for less than $100. So, for less than double the price of an MFM hard drive of comparable size, we can switch to SCSI and have the occasional use of the big disk and tape drive. I've heard that you should buy the SCSI controller from the same people you buy the disk from, so I looked in the R-Squared catalog and sure enough, they sell a SCSI controller to attach their drive to an AT for $1600! And a 91 Mbyte, internal hard drive for $1725! So what is wrong here? What is it about SCSI controllers that can support price differences so large? What does a $1600 controller do that a $100 controller doesn't do? There must be something I don't understand. Thanks for any help you can offer. Tim Sullivan (tims@goshawk.lanl.gov)
rick@always.com (Rick Wagner) (05/21/91)
In article <TIMS.91May16115641@infidel.infidel.lanl.gov> tims@infidel.lanl.gov (Tim Sullivan) writes: > ... So, for less than double the price of an MFM >hard drive of comparable size, we can switch to SCSI and have the >occasional use of the big disk and tape drive. This may not be as easy as it seems. I beleave that the Sun formats the SCSI drive to 1024 byte sectors, while DOS will want 512 byte sectors. The Exabyte shouldn't be a problem though. >I've heard that you should buy the SCSI controller from the same >people you buy the disk from, so I looked in the R-Squared catalog and This can be helpfull if they verify that the whole system plays together. This means they have tried the drive and controller in the package you are selling. On the other hand, if you are running standard applications, a good source is to ask the drive manufacturer which adapter they recommend. Then check with the adapter manufacturer and make sure they support what you are doing. >sure enough, they sell a SCSI controller to attach their drive to an >AT for $1600! And a 91 Mbyte, internal hard drive for $1725! > >So what is wrong here? What is it about SCSI controllers that can >support price differences so large? What does a $1600 controller do >that a $100 controller doesn't do? There must be something I don't >understand. Seems a bit steep; our adapter lists for $249, others are higher (up to $350 I think) down to about $50. These are MFSRP; street prices are generally lower. The difference in price is: performance, included drivers, functionality, and marketing. Might be that these guys are selling with a software package or some specialized system into a niche market; other than that, I don't know what could justify that kind of pricing. > >Thanks for any help you can offer. > >Tim Sullivan (tims@goshawk.lanl.gov) Hope I helped. --rick -- =============================================================================== Rick Wagner / Always Technology email: rick@always.COM 31336 Via Colinas, Suite 101 Voice: 1-818-597-1400 Westlake Village, CA 91362 Fax: 1-818-597-1496
phil@brahms.amd.com (Phil Ngai) (05/22/91)
Interesting that a guy from Always corp responds to this thread. I would seriously consider one of their products if I were ever brave enough to try SCSI on a PC. But I'm more of an ESDI/IDE kind of guy... --
plim@hpsgwp.sgp.hp.com (Peter Lim) (05/22/91)
/ phil@brahms.amd.com (Phil Ngai) / 1:17 am May 22, 1991 / writes: > Interesting that a guy from Always corp responds to this thread. > I would seriously consider one of their products if I were ever > brave enough to try SCSI on a PC. But I'm more of an ESDI/IDE kind > of guy... > You might want to try if you run out of disk space. I have the Always IN-2000 SCSI adapter in my system. It plays together with my existing ESDI drive (have also tried and verified that it plays with IDE drive). Togather with a SyQuest device driver, it allows me to have 3 hard drives on line at the same time (ESDI, SCSI and SyQuest). I have also attached an Archive Viper tape drive to the SCSI host adapter. The IN-2000 isn't a performance screamer (about 1MByte per sec transfer rate); but the manual specifically said that it does not use DMA and avoided a lot of incompatibility. I still haven't figure out why that is so, but the IN-2000 seems very compatible (I also have Sound Blaster) to me. Ran with Windows 3.0 enhanced mode straight without the need to set VirtualHDIrq=false (or something similar). I am very satisfied with this adapter and Rick Wagner has been very helpful when I needed help on getting new SyQuest device driver and SCSI BIOS ROM upgrade. I heard that Always had came out with an EISA SCSI adapter which can deliver about 3 - 4 MByte per sec. Anyone has any more info ? ** Obviously I am not affiliated with Always in any ways except as a very satisfied customer. Regards, ___o``\________________________________________________ ___ __ _ _ Peter Lim. V````\ @ @ . .. ... .- -> 76 MIPS at under US$20K !! --- -- - - /.------------------------------------------------ === == = = >--_// . .. ... .- -> 57 MIPS at under US$12K !! `' . If you guessed SUN, IBM or DEC, you are wrong ! E-mail: plim@hpsgwg.HP.COM Snail-mail: Hewlett Packard Singapore, Tel: (065)-279-2289 (ICDS, ICS) Telnet: 520-2289 1150 Depot Road, Singapore 0410. #include <standard_disclaimer.hpp>
gerardka@hobbes.ism.isc.com (Gerard Kam) (05/22/91)
In article <TIMS.91May16115641@infidel.infidel.lanl.gov> tims@infidel.lanl.gov (Tim Sullivan) writes: <deleted> >So what is wrong here? What is it about SCSI controllers that can >support price differences so large? What does a $1600 controller do >that a $100 controller doesn't do? There must be something I don't >understand. > The "SCSI controller" is more correctly called a SCSI host adapter. Its function is to provide an interface between the CPU system bus (ISA, EISA, Microchannel) and the SCSI bus. The host adapter can be so simple as to require complete CPU operation for control and I/O (programmed I/O). A step up would have direct memory access (DMA) data transfers. The fancy ones have on-board processors and large buffers. These are very common on VME and Multibus SCSI adapters. Since EISA and Microchannel are also multi-processor buses, there are a few intelligent SCSI adapters for those also. Gerard
jrd@cc.usu.edu (05/23/91)
In article <TIMS.91May16115641@infidel.infidel.lanl.gov>, tims@infidel.lanl.gov (Tim Sullivan) writes: > > I am confused about the SCSI interface. Let me describe the problem I > was trying to solve and hope that someone can explain why I was wrong. > > A Sun network here at the Lab needed more disk space and tape backup, > so they went out and bought an external box from R-Squared that has a > 1.2Gbyte hard drive and a 2.3 Gbyte Exabyte tape drive. It interfaces > to a Sun throught the Sun SCSI port. No problem. > > Now we have an AT and a frame grabber that takes data off of a video > camera. For something that we want to do, we are limited by the size > of our hard disk, which coincidentally died. So we said, why don't we > replace the dead MFM hard disk with a small SCSI disk and when we need > to we can bring the R-Squared system over and use with the AT? A 150Mb > SCSI drive might cost us $750 or so, and a SCSI controller can be > found for less than $100. So, for less than double the price of an MFM > hard drive of comparable size, we can switch to SCSI and have the > occasional use of the big disk and tape drive. > > I've heard that you should buy the SCSI controller from the same > people you buy the disk from, so I looked in the R-Squared catalog and > sure enough, they sell a SCSI controller to attach their drive to an > AT for $1600! And a 91 Mbyte, internal hard drive for $1725! > > So what is wrong here? What is it about SCSI controllers that can > support price differences so large? What does a $1600 controller do > that a $100 controller doesn't do? There must be something I don't > understand. > > Thanks for any help you can offer. > > Tim Sullivan (tims@goshawk.lanl.gov) --------------------- Tim, Yup, a misunderstanding. It is possible to spend $1600 on a SCSI controller for an AT, but you have to work hard on it. That's the price for a VAX SCSI controller. Ask R Squared for an Adaptec 1542B controller (under $300) and a good drive (680MB units go for $1500-1700 these days as a benchmark figure). Adaptec supplies drivers with their "kit" package at that price. If they can't provide then feel safe in purchasing the controller from an official Adaptec distributor and use it with almost any SCSI drive around. The under $100 controllers are too simple minded for a high performance drive (recall, these things escalate into more and bigger drives). Joe D.
phil@brahms.amd.com (Phil Ngai) (05/24/91)
plim@hpsgwp.sgp.hp.com (Peter Lim) writes: >I am very satisfied with this adapter and Rick Wagner has been very helpful >when I needed help on getting new SyQuest device driver and SCSI BIOS ROM I can believe that Always has good customer support, but this need to upgrade drivers is what scares me off. I want to buy a disk controller, plug it in, format my disk, and use it. My WD1007 does that. What if I want to run something really weird, like Novell Netware, and it's not supported, or Novell comes out with Version 4.000 and it starts flaking out every 3 days. It gives me nightmares and I like to have my sleep uninterrupted. -- For the Welfare system to flourish, its clients must not. Conflict of interest?
iverson@xstor.com (Tim Iverson) (05/25/91)
In article <1991May20.221754.1226@always.com> rick@always.com (Rick Wagner) writes: >In article <TIMS.91May16115641@infidel.infidel.lanl.gov> tims@infidel.lanl.gov (Tim Sullivan) writes: >> ... So, for less than double the price of an MFM >>hard drive of comparable size, we can switch to SCSI and have the >>occasional use of the big disk and tape drive. At an (off-the-cuff) guess, SCSI should only be about 10% more. Less than double sounds like you're being rooked. >This may not be as easy as it seems. I beleave that the Sun formats >the SCSI drive to 1024 byte sectors, while DOS will want 512 byte >sectors. The Exabyte shouldn't be a problem though. You're right that it won't be easy, but not because of the sector size. Sun systems use a 512 byte sector format, just like DOS and the various PC Unixes. The problem is the partition table. A Sun label (what Sun calls their partition table) is placed on lba 0. A DOS/Unix partition table (what IBM calls their label) also gets placed on lba 0. They are not compatible. If you don't mind re-labeling and mkfs'ing (Sun) and repartitioning and formatting (DOS) every time you move the drive back and forth, then you can share the drive without any special software. If you don't want to do this, you'll have to write a driver that allows one of your two OSes to talk to a drive formatted for the other. Or, you could use PC-NFS. The Exabyte may be a problem under DOS - you'll need software from someone that will allow you to access it; DOS can't do it alone. In fact, most ISA host adapters do not come with software to do this. You'll have to shop for it. >>I've heard that you should buy the SCSI controller from the same >>people you buy the disk from, so I looked in the R-Squared catalog and Try it before you buy it - get an eval set or if they won't do that, then ask them to come out and demo or go see one somewhere, or (well, you get the picture). >>sure enough, they sell a SCSI controller to attach their drive to an >>AT for $1600! And a 91 Mbyte, internal hard drive for $1725! Wow. For that price, it better be a real special system. For a 100MB scsi subsystem, I would guess $500 (we sell them, but you'll have to talk to a salesman to get the real story). >>So what is wrong here? What is it about SCSI controllers that can >>support price differences so large? What does a $1600 controller do >>that a $100 controller doesn't do? Hellifino (the small pink kind found in whiskey jars ... :-). Give 'em a call and ask. Could be that they do something so nifty it would be a bargain at twice that, but it would have to be something truly awesome. >>Tim Sullivan (tims@goshawk.lanl.gov) >Rick Wagner / Always Technology email: rick@always.COM - Tim Iverson iverson@xstor.com -/- uunet!xstor!iverson