Hardware Newb Questions: What Do All Those Numbers Mean?

[GamingMouse]

I am quite confused by the barrage of numbers that accompanies the description of the various pieces of computer hardware. I would be very grateful for any explanations. My first question is about hard drives. Consider the following:

Maxtor (6B200M0) DiamondMax Plus 10 200GB SATA 7200 RPM 8MB Cache

The 200GB part I get -- that's how much data it can hold

SATA (serial ATA) -- I know that this is vaguely good (in comparison to non-serial ATA) but have no idea how or why.

7200RPM -- I know this is how fast the HD "spins," but have no idea, eg, why a hard drive needs to spin, or why it's good when it spins faster. I also know that 10K RPM is considered top of the line. But how much better is it than 7200 RPM? Is it (10/7.2)% better? Is it (10/7.2)% faster? But I also know that "speed" doesn't make sense in a vacuum -- ie, it depends on the CPU, the RAM, and (perhaps???) the HD cache as well. But if this is so, then what exactly is so good about more RPMs?

8MB Cache -- I don't what this is, or why it's good to have more.

??? -- Any other important metrics that I've missed.

Thanks,
gm

 

[Matthias99]

Read this. 😛

 

[YOyoYOhowsDAjello]

10k isn't top of the line, there are SCSI drives that are 15k (maybe some faster ones too)

A harddrive is made up of spinning platters with a little arm that swings back and forth over the rotating surface below it (kind of like a record player). If the disk rotates faster, info can be taken off it faster.

There's no easy way to say how much one drive will perform compared to another. Drives with the same specs made by different manufacturers will perform differently.

SATA gets you almost no real performance increase today. The drives themselves are basically PATA drives with a new interface. You're paying for the smaller cable now.

A larger cache helps most when transferring lots of small files. It's kind of like a buffer for the drive.

Generally you should be looking at 7200rpm drives with 8mb cache like the one you listed.

 

[GamingMouse]

Matthias,

Thanks for the link and Yoyo, thanks for the explanation.

One thing still confuses me about buffers. The explanation on Matthias's link says that buffer size is one of the most important factors in speed, and that a drive spends most of its time reading to and writing to its own buffer. If that is the case, I'm confused as to how the buffers speed things up. For example, I make a request for file X. The HD spins over to the position where X is stored, write the data to buffer, and then (here I'm guessing) the data gets read into the RAM, where it is used. Why not just write directly from the HD into the RAM? I'm sure this reflects some basic misunderstanding on my part, but I'd appreciate any clarification.

gm

 

[jackschmittusa]

The buffer is comprised of very fast ram. The hd makes guesses at what you might need next (don't laugh, it often does it well) and loads that into the buffer. Retrieving it from the buffer is much faster than reading it from the platters. The larger the buffer, the more likely it contains what you need next.

 

[GamingMouse]

Originally posted by: jackschmittusa
The buffer is comprised of very fast ram. The hd makes guesses at what you might need next (don't laugh, it often does it well) and loads that into the buffer. Retrieving it from the buffer is much faster than reading it from the platters. The larger the buffer, the more likely it contains what you need next.

Interesting.. Thanks very much for that.