|March 14, 2004
Here is the question this
article is tries to answer: For older computers, when you add a new modern
hard drive, do you need to buy an add-in PCI IDE controller or is the onboard
IDE controller fast enough?
Many of us use older hardware
for servers, with good reason: webserving isn't all that CPU intensive
for small sites. Of all the old computers, the Pentium 2 and Pentium
3's are still very popular because they are decently fast and relatively
I have an old computer, a
dual Celeron 366 overclocked to 550 on a Tyan
Tiger 100 motherboard. I recruited this computer to be my network
file server and webserver test bench. When I started to install hardware
into it, I realized that the IDE hard disk controller on this BX motherboard,
like all other motherboards from its time, is rated to run at 33 Megabytes
per second. Back in the day, this was plenty fast since
hard drives couldn't deliver 33 MB a second anyways. But today, we
have hard drives that are rated up to 133 MB/second.
Don't be mislead by the 33
MB/second or 133 MB/second. Your hard drive can sustain transfer
rates that are much lower than those numbers would suggest. However,
your hard drive can transfer at very high rates through the onboard cache
that is on all hard drives. Most drives have at least 2 Megs of cache
onboard and more and more are coming out with 8 or 16 Meg caches.
Since the cache is essentially RAM and is very quick, the cache can have
burst transfers rates that are much higher than what is read directly off
the hard disk platters. These bursts only last as long as there is
data in the cache.
Now, when you connect a newer
fast hard drive to an older slow IDE controller, 2 things might happen.
1. The old controller won't recognize the size of your hard drive
because it's too big. 2. If the controller does recognize the
hard drive, the hard drive will be slower on the old controller than it
would be on a newer faster hard disk controller. The alternative
is to buy a newer PCI IDE controller that can run at the same speed as
the new hard drive.
The hard drive I plan on
using with this computer is a 40 gig Maxtor DiamondMax Plus 8. Here's
the info on that drive:
DiamondMax Plus 8
Fortunately, the hard disk controller
on the Tyan Tiger 100 was able to recognize the drive with no problem.
I was able to install and run Windows XP just fine. However, I was
curious how much performance difference there would be between the onboard
IDE controller rated at 33 MB/second versus an add-in PCI IDE controller
card that is rated at 133 MB/second. So I decided to do a little
testing. I picked up a very popular IDE controller:
Capacity of 40.0 GB
2 MB Cache Buffer
10 ms average Seek Time
Ultra 133 TX2
I ran a simple benchmark on
the hard drive when it was connected to the onboard IDE 33 MB/second controller
and when it was connected to the Promise Ultra 133 TX2 133 MB/second controller.
The benchmark I used was Simpli
Software - HD
Tach version 2.7. Since I didn't register this copy, I only ran
the READ benchmarks:
Handles up to 4 Ultra ATA/133
Drives or Devices
CRC Error Checking Up to 133
Here is the drive on the
onboard IDE disk controller on the Tiger 100 motherboard which uses a BX
chipset. This is using a standard 40 pin ribbon cable.
Here is the exact same drive
on the same computer, but instead of using the onboard IDE controller,
it's using a Promise Ultra 133 TX2 IDE controller in a PCI slot with a
80 pin ribbon cable.
Here is a comparison of the
data from the benchmark:
Onboard IDE controller
Promise Ultra 133 TX2
As you can see, the Promise
Ultra 133 TX2 allows the hard drive to function at a much higher rate across
the board at all levels, not just at the Read Burst Speed. The values
are almost double for all the categories. For the onboard IDE controller,
you can see that the 33 MB/s max is really holding back this hard drive.
For the Promise Ultra 133 TX2, you can see that although the drive is much
faster, it still doesn't reach 133 MB/second, even with the Read Burst
Speed which reads from the cache. This means that using a controller
that is rated up to 100 MB/s would be good enough for this drive.
In fact, I have yet to test a hard drive that exceeds 100 MB/s. Even
my Western Digital Special Edition drives with 8 Meg cache don't burst
over 100 MB/s.
Aside from the benchmarks,
using the computer with the hard disk connected to the Promise Ultra
133 TX2 felt quite a bit faster than when it was connected to the onboard
IDE controller. Although you might argue that you don't do a lot
of data transfers, the burst speed from the hard drive across the hard
drive controller really gives the computer a snappier feel.
Now what's the bottom line?
Well, I personally think it's worth the 20 or 30 bucks to buy an add-in
controller card. It will make using an older computer feel faster
and more responsive. Also, an add-in card will recognize larger hard
drives that your old onboard controller might not. It's really up
to you. I just wanted to provide some numbers by which you can compare
the same drive on 2 different controllers.
As a side note, I am a big
fan of Promise hard disk controllers. I have used almost all their
controllers and have been extremely pleased. I've found their products
to be of reasonable price and good quality. Their RAID controllers
are also very good. I use a Promise IDE RAID controller on this very
webserver. If you are thinking about IDE RAID, I highly recommend
the Promise RAID controllers. They have a solid reputation, good
drivers online, and aren't too expensive. Used Promise RAID controllers
are especially a good deal and can be found on a lot of buy/sell forums
on the Internet. And no, they're not paying me to say this.
This little rant comes from years of experience using various controller
cards from different companies. I now pick Promise.
Including that last detour,
this article is quite a bit longer than I had expected. Originally
I just wanted the throw up 2 screen shots and say "Hey, 133 is faster than
33". Oh well, long live older hardware!