With the prices of SCSI (small computer system interface) devices becoming cheaper and cheaper we’re now starting to see large high end SCSI hard drives in personal computers which was something you would only see in workstations and servers a few years ago. Well how times have changed, these days any real gamer has a full blown SCSI system going on and for those who love to play Starcraft of Quake 2 while burning a CD, a SCSI setup is almost a must. As of right now the most common SCSI connection is either Wide Ultra(UW),Ultra2 SCSI LVD or Wide Ultra2 SCSI LVD.

So what is Internal Transfer Rate?

Well the Internal Transfer Rate is the speed of which data can move inside our hard drive. Now the big misunderstanding that people have is that they think the faster the SCSI controller transfer rate the faster their hard drive will be. Well that’s not entirely true. But before we get to that point I should tell you a little about how the hard drive is rated in terms of speed. The first thing we’ll look at is the Internal transfer rate which is the rate at which data can be moved and read inside your drive. So the next time you load up and move files around inside your drive this is the number that you should be looking at and it has little to do with your external transfer rate which is where the SCSI controller comes in. There’s also other numbers and specs that you should look for before buying a hard drive and you’ll be able to find that info in "A Closer look into the hard drive".

Ok so what the heck is the External Transfer rate for then?

The external transfer rate like I said before is where the SCSI controller comes in. When people say that they have a 40Mbits/sec SCSI transfer rate what that means is the speed of which data can travel through the SCSI cable. Now the transfer rate can also effect the speed of which data can go from the hard drive to the ram but unless you have like 512mb’s of ram getting anything higher then a 20Mbits/sec connection isn’t going to speed up your computer. So what’s the use of getting a high speed SCSI controller then? Well there really isn’t much of a reason to spend that extra money on a 80Mbits/sec SCSI controller unless you have more then one hard drive cause without another high speed drive the 80Mbits/sec external transfer rate wouldn’t do you much good at all, in fact switching from 40Mbits/sec to 80Mbit/sec on a system which only has one hard drive would not increase system performance what so ever(well in terms of you being able to see). But if you just happen to be one of those lucky ones who do have say two of Seagate’s Cheetah drives then a 80Mbit/sec SCSI controller might be something to think about if you plan to move a lot of data around between the drives. Another reason that you might want to get a 80Mbit/sec SCSI controller is when you have more then one drive and plan to do a lot of multitasking cause each line or cable can only move so much data through it at any given time which means that when you have something say a server and there was 5 drives running at the same time in one line then that means with a 80Mbit/sec controller each drive would have an external transfer rate of 16Mbit/sec. Oh ya if you are running a server with many hard drives you might want to either get more then one SCSI controller or a SCSI controller which is multi-channeled for better performance.

Show me the MONEY!

Ok I’ve put together a system to show how a 40Mbit/sec and 80Mbit/sec controller would perform in everyday jobs for the average user(hey I don’t the hardware or money to put together a server with a ton of drives here). Here’s what the system looks like and I’ll be using Diamond’s Fireport 40 SCSI controller which runs at 40Mbit/sec and Tekram’s DC-390U2W SCSI controller which runs at 80Mbit/sec.

Intel Celeron 300A overclocked to 450mhz

128MB’s of PC100 SDRAM

VideoLogic’s Apocalypse 5D Video card

Quantum’s Viking II hard drive(split into 2 drives, C and D.)       

Kenwood’s 40X true speed CD-ROM

SB LIVE Value sound card

Voodoo2 Video card

Showed below is the time it takes for each configuration to move 345mb(3,343 files, 40 folders) of data. Times are in minutes:seconds

Any ways what is showed here is that there is very little difference between the two controllers when it comes the performance of a single hard drive which means that you people out there who are thinking of getting a 80Mbit/sec controller should only do so if you plan on getting another SCSI hard drive with the same speed or higher in terms of external transfer rate. But that 13 seconds difference is nice but definitely not worth buying a SCSI controller that’s most then twice the price of the Fireport 40 unless your one of those speed freaks. Another thing that I should mention is that the Fireport 40 even though it’s about 13 seconds slower seems to be more consistent when it comes to it’s transfer times.

Please note that I only have one SCSI drive or otherwise if the data was moved between two drive physical drives the Tekram DC-390U2W should put up numbers that are twice as good as Diamond’s Fireport 40 but overall the times would be a lot higher cause then it’ll be an external transfer and not a internal.

Showed below is the time it takes for each configuration to delete 345mb’s worth of data(3,343 files, 40 folders). Times are in seconds:milliseconds.

Well with less then a one second on average difference need I say more?

Showed below is the time it takes for each configuration to load Starcraft. Times are taken in seconds:milliseconds.

Again with less then a one second difference I think my point has been proven. The only think that I could think of that would explain the difference would be in the time it takes the SCSI controller to communicate with the system ram but other then that I’ve can’t think of much else cause I’ve turned almost everything off when I did these tests in order to eliminate background operations and CPU usage.

Well with very little performance difference between the two SCSI controllers when you use one hard drive I don’t see any reason why anyone would want to spend the extra money on a 80Mbit/sec controller over a 40Mbit/sec controller unless your planning on putting more then one SCSI hard drive into your computer. So in the end, the thing I would recommend for all your SCSI freaks out there would be to spend the extra money on a hard drive with faster internal transfer rates then on a faster SCSI controller. I mean even if you do get two or more SCSI drives how much data are you going to move around any ways and are you really going to watch like 3 or 4 movies at the same time on your  monitor?

Copyright 1999 - All rights reserved Hilbert Hagedoorn