SATA Drives and confusing terminology

[doctordoctor]

I built a system about 8 months ago with the following:

DFI LANPARTY UT nF4 Ultra-D Socket 939 NVIDIA nForce4 Ultra ATX
Western Digital Caviar RE WD2500YD 250GB 7200 RPM Serial ATA150 Hard Drive

(WD Link here: WD2500YD)

(note the WD link won't hop right to the drive, but you can select it from a pulldown menu)

with an AMD Opteron 165


My hard drive is approaching capacity, and I want to purchase another one. Western Digital has discontinued the drive I purchased, so I was thinking of purchasing this one:

WD2500KS

and here at NewEgg 2500KS.

Question 1:

I cut and pasted the "tagline" of the original drive I purchased from my NewEgg invoice above. What I don't understand is the Serial ATA150 portion. According to the specifications on WD's site, the buffer to host transfer rate is 3.0GB/second. Thus, I'm wondering if I'm confusing the 150 for something else (i.e. other than a 1.5gb/second rate). So, do I have a 3GB/S drive (SATA II) or not? If so, what does the ATA150 refer to?

Question 2:

In purchasing a new drive, I am considering the 2500KS or JS. The only difference I can see is the buffer size (16MB vs 8MB). The seek times between these two drives (and the one I currently have) are all identical. It seems obvious to me to purchase the drive with the larger buffer size, however, I'm wondering, is there a general rule as to which part of data transfer is the RATE LIMITING STEP?

i.e. will I notice an appreciable difference with regular computer use between a 16 MB and 8MB cache or for that matter, between 1.5 and 3 gb transfer rates?

And finally, since the seek times are the same, and since the specifications of the drive I have indicate that my drive has a 16MB buffer, then what is the real difference between the 2500KS and the 2500YD which I already own?

I apologize if this question is far too mundane.

 

[Roguestar]

SATA1, ATA150, 1.5Gb/s are all the same SATA 1.0 standard.
SATA2, ATA300, 3.0Gb/s are all the same SATA 2.0 standard.

If your motherboard has SATA ports you're good. SATA 2.0 will downgrade on an SATA 1.0 port, and SATA 2.0 ports support SATA 1.0 connections.

16Mb Cache is better than 8Mb cache, you may notice a small improvement when switching between many open programs or editing a lot of documents at once.
The difference between 1.5 and 3.0 Gb/s is a little larger, though, and transfer times between drives will be a lot faster on the latter.

As to the differences between the KS and YD:

"(NOTE: Drives manufactured prior to March 1, 2006 have a 1.5 Gb/s buffer to host transfer rate.)"

So if your YD is slightly older it'll have a slower transfer rate than the newer KS model.

 

[computer]

According to WD, both of those drives are SATA300. The info from NewEgg is obviously (and no surprise), incorrect. But when I go there it doesn't say SATA150, it says 300. (or 3gb/sec). Did you check it recently? They've apparently fixed the text.

Seek times are not that big of a deal. What's more important is areal density, rotational speed, (and maybe some NCQ or TQ things). If your mobo is not SATA300 capable, then it's moot. If it is, a SATA300 is only faster when doing the interface transfer benchmarks, and not necessarily with other benchmarks. For example, the WD ADFD Raptor drives are faster than any SATA300 drive, except in the interface transfer results, which is logical. That one benchmark has very little to do with actual PC use. So don't buy a HD just based upon it having a SATA300 interface. Buffer size however, is different. You can see a difference in those.

WD doesn't state areal density specs anymore, so they could be different between those two drives you asked. For the KS, they say the "Buffer To Disk" is 748mb/sec, which is 93MB/sec. For the YD model they say it's 61MB/sec. (I really don't understand that since they are both SATA300).

 

[doctordoctor]

Thanks for both of your replies, now I see the issue:

1. Actually, NewEgg's terminology was right, as far as I can tell. As Roguestar notes, there is a parenthetical caveat on Western Digital's Specifications page that reads (quote): (NOTE: Drives manufactured prior to March 1, 2006 have a 1.5 Gb/s buffer to host transfer rate.).

It then proceeds to list the transfer rate at 3.0GB/s. I purchased my system on April 17 2006, so I suspect that I have a 1.5GB drive rather than the updated SATA II interface.

2. My board supports 4 SATA drives at 3GB/s so that shouldn't be problem. Looks like I'll be getting the 2500KS.

Thanks for your input.

 

[Roguestar]

Originally posted by: doctordoctor
Thanks for both of your replies, now I see the issue:

1. Actually, NewEgg's terminology was right, as far as I can tell. As Roguestar notes, there is a parenthetical caveat on Western Digital's Specifications page that reads (quote): (NOTE: Drives manufactured prior to March 1, 2006 have a 1.5 Gb/s buffer to host transfer rate.).

It then proceeds to list the transfer rate at 3.0GB/s. I purchased my system on April 17 2006, so I suspect that I have a 1.5GB drive rather than the updated SATA II interface.

2. My board supports 4 SATA drives at 3GB/s so that shouldn't be problem. Looks like I'll be getting the 2500KS.

Thanks for your input.

March, then April, surely?

I would surmise that your hard drive has the SATA 2.0 3Gb/s interface. You could test with something like SiSoft Sandra (or whatever the kids are using to perform component analysis and benchmarks these days ).

I can vouch for the 2500KS being reliable and speedy, in fact I intend to buy another this month!

 

[computer]

SANDRA won't give much of an indication of interface transfer speed. For that, you'd want to use H2bench (free) which has that exact test in it. If it's SATA300, it can be somewhere between about 150MB and 200MB/sec. (on that specific program).

When you bought the drive may be irrelevant. You have to look on its label at the manufacturing date.