tssdan, on 20 Aug 2013 - 10:37 PM, said:
You are so flipping amazing. Thank you so much for your detailed response.
So there isn't like an average speed in megabytes that each interface caps out with a traditional HD vs. an SSD? My main point of confusion is that with the faster USB 3 connection, why do we still use SATA? If SATA is pretty much as fast as USB 3 then why don't we have SATA ports lined up on the sides of our computers instead? SATA has been around for a long time, right? I hear that Ethernet is super fast too. Where does that fall in? Why don't we use Ethernet for everything?
So when you say X Gbps that just means it could theoretically transfer 1024 megabytes per second?
I'm so sorry for all the questions. I have just always wondered why we have so many different interfaces. I'm thinking that the reason is for speed...which is why I was trying to make a chart comparing them with their average speeds with an SSD vs. HD.
Thank you so much for your time!
No problem. Asking questions is how we learn, whether those questions are out loud to other people who then provide answers or internally to ourselves to drive our own searches for answers. :D
I will answer the easy question first:
If SATA is pretty much as fast as USB 3 then why don't we have SATA ports lined up on the sides of our computers instead?
Because SATA is not nearly as versatile as USB (whether USB 3 or 2 or 1). You can connect mice, keyboards, printers, scanners, etc to USB but not SATA. SATA is purely a storage device (hard drive, SSD, optical drive) connection.
Now, while you tend to a lot of USB ports on computers, in recent years, you can find eSATA ports on computers. This is because eSATA (basically an external version of the SATA connection) was a way faster option compared to USB 2.0. For example, I would tend to use eSATA external drives rather than USB 2.0 drives for my Windows computer (and more and more for my one Mac). With the more broad prevalence of USB 3.0, however, I suspect that eSATA will potentially fall out of use...and SATA in general will return to just an internal connection for the most part.
And yes, SATA has been around for a while (i.e. the last decade or so)
Ethernet fails in roughly the same boat. Ethernet is a networking connection. It can indirectly be used as a storage connection with the use of a server or NAS. There are scanners and printers that connect by ethernet (or WiFi). Case in point, my one printer is an "all in one" inkjet that I can use to scan, print or copy...and it is connected by way of an ethernet connection.
But, ethernet does not really work for things like mice or keyboards (there are round about ways to achieve a similar result through ethernet, but most, if not all, still require at least ONE computer with a USB mouse and keyboard).
The much tougher question is "why don't we just use USB 3.0 for everything?"
Well, the easy part is that it does not really do everything that we might want. It does not really do networking (other than you can plug in a USB based network adapter whether that be an ethernet adapter or WiFi dongle). Originally, it was also not really designed for storage purposes, but has kind of grown into that area. It is still not really "optimized" for storage purposes, but it has gotten faster enough that it is no longer the bottleneck.
So, why not have all storage connect by USB 3.0, including internal storage? It is possible that this may happen. USB 3.0 is still relatively "young" and has only really started to be "standard" on new computers. Even given that, it is possible that SATA likely will stay in use for internal connections for awhile. This may be somewhat related to cost...while I don't know for sure, I suspect that USB 3.0 cost more to implement.
There are also inherent advantages to SATA over USB even though USB 3.1 is potentially faster than even the currently available fastest SATA connection in terms of theoretical speeds. USB is processor dependent (I believe this is still true of USB 3.x, albeit less so). As a result, even though USB 3.0 might be faster than SATA, I believe it eats some of your CPU cycles while SATA may not. This article might help some:http://www.brighthub.com/computing/hardware/articles/24772.aspx
The end result is that different connection types have different strengths and weaknesses. Thus, we tend to use different connection types for different things. At the end of the day, USB will be the most commonly used connection type for the wide variety of purposes. It is also the connection type that you might only see on some PCs (for example, my first MacBook Air that I had only had two USB 2.0 connections and a MiniDisplay port for an external monitor...no ethernet port unless you got a USB to ethernet adapter). But, for most PCs, you will have additional connections beside USB connections as those other connection types work better for specific things.
Odds are for internal storage, SATA will remain king at least for awhile to come. For external storage connections, USB 3.x will likely be king for the near future mainly because those same ports can also be used for mice or keyboards or printers. There will be a market, however, for those who need/want to use Thunderbolt (kind of the main competitor for USB 3.0 in many ways). For example, one big advantage of Thunderbolt is that you can get Thunderbolt to Firewire adapters to allow you to make use of old Firewire drives that one may have (i.e. if one is a Mac user)...while I don't believe this is possible with USB 3.0.
And yes, 1 Gbps is roughly 1000 Mbps (whether it is 1000 or 1024 is somewhat dependent on context...this is the same thing that causes some computer OSs to report a hard drive as smaller than what was advertised on the box when you bought it).
As to average speed values, I am not aware of any widely published overall average speed for different connection types whether for hard drives or SSDs. This is particularly because there are lots of variables. As I noted, "speeds" can be impacted by size of files transferred, computer used, type of drive used, number of drives used (i.e. a external USB 3.0 drive using two hard drives in a RAID 0 array will be faster than a USB 3.0 drive using 1 drive...but both are using "hard drives), etc. So, as I said, your best bet is to keep in mind the general progression of speed of connection types. And if you REALLY need to determine relative "speeds" look for actual reviews of actual external drives.