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Ultra ATA/100 and UDMA/100

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Golgo13

IS-IT--Management
Aug 10, 2008
5
JP
I plan on getting a new computer soon, and I have a quick HD question: If the motherboard I'm getting says it supports UDMA/100 and the hard drive I plan on buying is Ultra ATA/100, will there be a problem? Could someone explain the differences, if any, between the two types?
 
The way I understand it, it's just a naming convention. UDMA is Ultra Direct Memory Access and ATA is AT Attachment. Both terms are just that, terms, they don't really mean very much. What's important is the 100, this is the theoretical burst transfer speed in MB/sec. Again, it will never run that fast so it doesn't really mean much. The two will work work just fine together. If you want to know a little more about it go here:


Justin
 
Have a look at Dintec's earlier posting and the responses to that (rather than repeat myself!). I found some very interesting information pertaining to this subject.

Hope this helps!
 
UDMA100 /UltraATA100 are naming conventions that indicate the same thing. This drive requires a controller with an enhanced IDE bus speed to maximize its potential. Most drives of this nature will run on slower speeds without a problem, but really shine once properly set up, including hardware support and software device drivers.

The predecessors were Ultra66/UDMA66, and Ultra33/UDMA33.

One caveat - you can't mix drive types on the bus. Can't have a 100 and a 33 on there - the whole thing will run at 33. So if you're mixing drives, keep the fast one by itself, and put the dinosaur on the secondary channel, or buy yourself an auxilliary UDMA100 adapter card.

If you don't have UDMA100 capability on your motherboard you don't need to replace it - just an adapter card will fix you up, extending the life of the motherboard (for those who were thinking about newer, faster drives). The performance increase will largely depend on the bus speeds, but you'll have nice burst rates.

Still, I'll stick with my 10K Cheetas heating my toes as they hum along on my LVD chain :)


 
Yes, the two numbers pertain to two entirely different things.
 
There is no difference mate.
UDMA is the same thing as ATA (AT).
Check out my post in the Hard Drives section on UDMA/ATA vs. RPM.

I strongly believe the revolutions on the Hard Drive disc is what counts, rather than 33/66/100/133 Megabytes a second. It needs to read the disc first, then transfer info through the cables.

my two cents.
compborder
 
I think we need an FAQ or 2 on this!

compborder, that's nearly right - RPM is a large factor in determining how well a disk performs. Check out Seagates' Cheetah drives, at 15,000 RPM, with a potential transfer rate of 160Mb/sec.

The biggest factor, however, is access time. The quicker a disk drive can access sectors on a platter, the faster, overall, the disk will perform. Hence it's advisable to choose a disk with 8m/s access time over a disk with 9m/s access time.

This can be aided by a large cache - some manufacturers are including caches up to 8Mb in the drive's electronics, while caching SCSI boards have been including a DIMM slot for some time. A cache, however, provides virtual access points, so can produce misleading figures in benchmarks. This said, a large cache is a very good thing.

The MB/sec quoted by most manufaturers is misleading, and refers to the drives "burst" rate - the fastest it has been timed at, usually reading data from the inside sectors.

More significant is the STR, or Sustained Transfer Rate. Good hardware sites, such as Tomshardware.com will post graphs so that you can get a good comparison.
 
CitrixEngineer,
I agree with everything you said but would like to correct that the burst transfer rate is caluclated reading the outside sectors, not the inside. Since the platters spin at a constant rate, more sectors pass under the head on an outside track rather than an inside. (Just to avoid any confusion.)
 
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