Adaptec SATA Card 150Mbps or 1.5Gbps. Which is it? Need 1.5

[ReddogCA]

I want a 1.5Gbps SATA PCI card for my workstaion. Adaptec's SATA RAID 1210SA says' it is "UP TO" 1.5Gbps. Other sites say it is only 150Mbps. How do I get 1.5Gbps?

 

[fishmahn]

SATA has a speed limit of 150mbps from the card to the drive (SATA2/II/IO/whatever is 300). Don't know how to get 1.5gbps out of that without 10 of those drives.

Mike.

 

[hergieburbur]

SATA has a speed limit of 150mbps from the card to the drive (SATA2/II/IO/whatever is 300). Don't know how to get 1.5gbps out of that without 10 of those drives.

Mike.

That is incorrect. Pay closer attention to the reading. The two are the same thing. SATA-I has a speed limit of 150MBps *(note the CAPITAL B, as in bytes). Companies market this as 1.5Gbps (lowercase b, as in bits. They use powers of ten instead of 8 to make it "easier to understand" and coincidentally more attractive). This is also the reason you never get the quoted size out of a harsd drive either.

You are getting caught up in the marketing gimmicks. The adaptec one is in fact only 150MBps, they all are. I would recommend you take a look at promise controllers while you are shopping. They are a bit cheaper, and in my experience perform very well.

 

[fishmahn]

That is incorrect. Pay closer attention to the reading. The two are the same thing. SATA-I has a speed limit of 150MBps *(note the CAPITAL B, as in bytes). Companies market this as 1.5Gbps (lowercase b, as in bits. They use powers of ten instead of 8 to make it "easier to understand" and coincidentally more attractive). This is also the reason you never get the quoted size out of a harsd drive either.

I didn't go to adaptec's site. Not my job to. You, however, can if you want to. Note the original poster didn't capitolize or lowercase his bits/bytes. I paid closer attention to the reading there.

May want to direct the appropriate part(s) of your comments to the OP instead of me... thx.

Mike.

 

[hergieburbur]

Don't take offense, since I was directing the comments at both of you. I am not attacking anyone. And you were incorrect in stating that SATA is limited to 150mbps. Regardless of what the OP said, if you ware going to offer advice, you should have at least made sure to get the 150MBps right.

To the OP, this is pretty much irrelevent anyway, unless you have a PCI-E or PCI-X SATA card, PCI will limit your transfers to a much lower speed.

 

[fishmahn]

Don't take offense, since I was directing the comments at both of you.

I'm not, however your post was specifically in a 'reply to Fishmahn', and as such I replied as if it was to me. Maybe indicating your intent to address the OP would help??

And you were incorrect in stating that SATA is limited to 150mbps. Regardless of what the OP said, if you ware going to offer advice, you should have at least made sure to get the 150MBps right.

Accepted.

Mike.

 

[hergieburbur]

I apologize for my lack of clarity in who I was responding to.

 

[nobly]

Companies market this as 1.5Gbps (lowercase b, as in bits. They use powers of ten instead of 8 to make it "easier to understand" and coincidentally more attractive).

Actually that's wrong too.
SATA uses 8B/10B encoding, hence it has some overhead, which sequentially limits the data transfer to 1.2Mbps = 150MB/s.

So 1.5Gbps = 150MB/s ONLY when referring to SATA. Consequently SATA 2 is 3.0Gbps = 300MB/s. Again these equations only hold true for SATA.

Sidenote: If you're getting a PCI card, you'll be limited by the PCI bus, which maxes out at 133MB/s.

 

[hergieburbur]

Companies market this as 1.5Gbps (lowercase b, as in bits. They use powers of ten instead of 8 to make it "easier to understand" and coincidentally more attractive).

Actually that's wrong too.
SATA uses 8B/10B encoding, hence it has some overhead, which sequentially limits the data transfer to 1.2Mbps = 150MB/s.

So 1.5Gbps = 150MB/s ONLY when referring to SATA. Consequently SATA 2 is 3.0Gbps = 300MB/s. Again these equations only hold true for SATA.

Sidenote: If you're getting a PCI card, you'll be limited by the PCI bus, which maxes out at 133MB/s.

You are partially correct, I forgot about the 8/10 encoding loss, though I think you meant 1.2Gbps=150MB/s However, SATA does not actually work at 1.5Gbps, it works at 1.5 GHz, and the 1.5 Gbps is a result of companies simplifying things for marketing reasons.

OP, if you want it explained, the reason is that 8/10 encoding is 80% efficient, so SATA working at 1.5 GHz gives you 1.20Gbps bandwidth, which divided by 8 equals 150MB/s.

As I and nobly said, the PCI bus will limit you well below that. You would be extremely lucky to get 133MB/s out of the PCI bus (that is the theroretical shared bandwidth, so any other devices, including most older ethernet controllers and any other cards you have, are sharing that bandwidth).

 

[nobly]

Gah! Stupid Mbps Gbps! Hehe, but yeah, you're right, I meant 1.2 Gbps there. I think too much programming is getting in the way of my fingers typing...

 

[hergieburbur]

Blame the marketers for trying to make their product more attractive. Though I have to admit, selling a "not quite 160GB" drive doesn't have the same ring to it.

 

[hergieburbur]

I'm still waiting to see a drive that can continually stress 150MB/s, let alone any of the others.

 

[hergieburbur]

I don't exactly put much stock in synthetic benchmarks, though they do mean more for HDs than processors.