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Interface Speeds with HD or SSD


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#1 tssdan

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Posted 12 August 2013 - 10:10 PM

Hi guys,

 

I’m a long time reader, but first time poster. First, I want to THANK YOU for all of the computer help you have given me over the years. I’m basically the “tech support guy” for my friends and family and without your awesome solutions here, I wouldn’t be as “smart” as I am today.

 

Anyway, this is something I have been trying to comprehend for a couple years now and I just still can’t understand it; thus, I have decided to just try and ask on the forums and make an account. I’m pretty sure this question is the equivalent of ‘How much does it cost to build a house’ because there are so many options/circumstances involved, but perhaps someone might be able to point me in the right direction, or water it down for me so I could understand it.

 

Basically, what I want to figure out is a comparison between all of the different interfaces and their speeds (USB 2, 3, FW, etc.) in megabytes per second (when people say megabits per second, I still don’t understand that or how to convert that--why do we even say that anyway? I’ll save that for another post) when connected to a HD or SSD. I know they all have theoretical speeds, but I think that’s just like internet speeds where you never really get close to the real thing, right?

 

As soon as I try to figure it out, I remember that the speed is going to be different when you have a 5400 or 7200 hard drive or even an SSD. When I throw an SSD in to the equation it seems that for the hundreds of SSDs that are out there, there isn’t a standard speed they read/write data at because they’re all different.

 

For years, I’ve known that the bottleneck of a computer is the hard drive, so what exactly is that bottleneck...exactly how fast could a HD max out at read/write speeds---especially across the various interfaces.

 

I’ve been trying to make a chart to keep it all straight:

 

NV4398d.png

 

Just wondering if someone might be willing to answer my questions and explain this to me, and let me know/update my chart to see if the information I am gathering is correct.

 

I apologize for such a stupid question. This has just been on my mind for a long time, and I just want to get it all straight!

 

Thank you,

Daniel


Edited by tssdan, 12 August 2013 - 10:12 PM.


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#2 dicke

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Posted 13 August 2013 - 08:52 AM

Hi Daniel,

I don't have answers to all of your questions but I can tell you that a byte is made up of eight bits.

Please don't apologize for your question. It would be stupid not to ask it - you would never learn.

When the answers are posted we will both have learned something :thumbsup:


Stay well and surf safe [stay protected]

Dick E


#3 smax013

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Posted 13 August 2013 - 11:23 PM

There is something wrong with your chart as your numbers do not match up with units. I am assuming you are meaning to be showing the "speeds" in megabytes per second as those numbers would be about right if it was megabytes. If so, then the units that you show should be "MB/s" not "mb/s". In general, "Mega" is always supposed to be shown with a capital "M", but it is not completely out of bounds to show it with a lower case. The big one (no pun intended) is the "b". A capital "B" means bytes while a lower case "b" means "bits". Thus, right now you are showing USB 2.0 for example as at 35 megabits per second...which is generally way too low. 35 megabytes per second (which equates to about 280 megabits per second) is not out of bounds for a typical USB 2.0 speed, although it can vary based upon a number of factors, including processor speed.

As noted by the other poster, 1 byte has 8 bits. Thus, if you are given a speed in megabits per second (i.e. Mbps or Mb/s), then divide it by 8 to get megabytes per second (i.e. MBps or MB/s). If you are give a speed in megabytes per second, then multiple by 8 to be megabits per second).

Now, as to how accurate your numbers are (assuming you meant to be using MB/s), that will depend.

I can tell you that Firewire 400 is generally faster than USB 2.0. This is largely because USB is a processor dependent protocol while Firewire is not. I can say that I have experienced this first hand on my own machines. As a result, I have traditionally use Firewire drives over USB 2.0 drives, including on my Windows machines even though I was exposed to Firewire first on my Macs. This article might also help:

http://www.pcworld.com/article/185415/article.html

Thus, your numbers for Firewire 400 vs. USB 2.0 seem off to me.

The other issue is that you are mixing up connection protocol (i.e. USB 2.0, USB 3.0, Firewire 400, Firewire 800, Thunderbolt, SATA) with what you are connecting (hard drive and SSD). To help with that, you should realize that generally speaking a hard drive CANNOT "saturate" (i.e. take full advantage of) a USB 3.0, Thunderbolt, or SATA (whether 1.5 Gbps SATA, 3.0 Gbps SATA or 6.0 Gbps SATA) connections. Thus, with those connections, the hard drive will be the bottleneck, whether it is a 5400 rpm or 7200 rpm or even a 10000 rpm drive). In other words, to more fully take advantage of USB 3.0, Thunderbolt, or SATA, you really need an SSD. For USB 2.0 or either of the Firewire protocols, then it is really the connection that matters.

Beyond that, there is little purpose to putting together a chart like you have as there are really just too many variable to really account for. Transfer speeds can be affected by the files size of the files copied, the computer used, etc.

I would say it is more important to just keep in mind a general order of speed of the connections, which from slowest to fastest is roughly:

USB 2.0
Firewire 400
Firewire 800
SATA/USB 3.0/Thunderbolt (technically Thunderbolt is the fastest, with SATA 6.0 Gbps likely being technically the next faster, then USB 3.0 more or less on the same level as SATA 3.0 Gbps with SATA 1.5 Gbps last...but in reality they are all about the same, especially with a single hard drive)

This article might help some as well:

http://www.macworld.com/article/2039427/how-fast-is-usb-3-0-really-.html

#4 tssdan

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Posted 20 August 2013 - 09:37 PM

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! :)

 

D

 

 

 

There is something wrong with your chart as your numbers do not match up with units. I am assuming you are meaning to be showing the "speeds" in megabytes per second as those numbers would be about right if it was megabytes. If so, then the units that you show should be "MB/s" not "mb/s". In general, "Mega" is always supposed to be shown with a capital "M", but it is not completely out of bounds to show it with a lower case. The big one (no pun intended) is the "b". A capital "B" means bytes while a lower case "b" means "bits". Thus, right now you are showing USB 2.0 for example as at 35 megabits per second...which is generally way too low. 35 megabytes per second (which equates to about 280 megabits per second) is not out of bounds for a typical USB 2.0 speed, although it can vary based upon a number of factors, including processor speed.

As noted by the other poster, 1 byte has 8 bits. Thus, if you are given a speed in megabits per second (i.e. Mbps or Mb/s), then divide it by 8 to get megabytes per second (i.e. MBps or MB/s). If you are give a speed in megabytes per second, then multiple by 8 to be megabits per second).

Now, as to how accurate your numbers are (assuming you meant to be using MB/s), that will depend.

I can tell you that Firewire 400 is generally faster than USB 2.0. This is largely because USB is a processor dependent protocol while Firewire is not. I can say that I have experienced this first hand on my own machines. As a result, I have traditionally use Firewire drives over USB 2.0 drives, including on my Windows machines even though I was exposed to Firewire first on my Macs. This article might also help:

http://www.pcworld.com/article/185415/article.html

Thus, your numbers for Firewire 400 vs. USB 2.0 seem off to me.

The other issue is that you are mixing up connection protocol (i.e. USB 2.0, USB 3.0, Firewire 400, Firewire 800, Thunderbolt, SATA) with what you are connecting (hard drive and SSD). To help with that, you should realize that generally speaking a hard drive CANNOT "saturate" (i.e. take full advantage of) a USB 3.0, Thunderbolt, or SATA (whether 1.5 Gbps SATA, 3.0 Gbps SATA or 6.0 Gbps SATA) connections. Thus, with those connections, the hard drive will be the bottleneck, whether it is a 5400 rpm or 7200 rpm or even a 10000 rpm drive). In other words, to more fully take advantage of USB 3.0, Thunderbolt, or SATA, you really need an SSD. For USB 2.0 or either of the Firewire protocols, then it is really the connection that matters.

Beyond that, there is little purpose to putting together a chart like you have as there are really just too many variable to really account for. Transfer speeds can be affected by the files size of the files copied, the computer used, etc.

I would say it is more important to just keep in mind a general order of speed of the connections, which from slowest to fastest is roughly:

USB 2.0
Firewire 400
Firewire 800
SATA/USB 3.0/Thunderbolt (technically Thunderbolt is the fastest, with SATA 6.0 Gbps likely being technically the next faster, then USB 3.0 more or less on the same level as SATA 3.0 Gbps with SATA 1.5 Gbps last...but in reality they are all about the same, especially with a single hard drive)

This article might help some as well:

http://www.macworld.com/article/2039427/how-fast-is-usb-3-0-really-.html

 



#5 smax013

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Posted 21 August 2013 - 12:42 AM

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! :)

D

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:

Quote
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.

#6 rotor123

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Posted 21 August 2013 - 11:48 AM

And to answer the question SSD is generally SATA 1, SATA II or SATA III with a very few IDE versions. The Speed of a SSD comes about due to its having no moving parts. Thus fragmentation does not affect it as any location can be accessed just as fast as there is no waiting for the platter to come around or the heads to change tracks.

 

This image shows that the transfer rate is basically flat

128-hdtune-ssd.jpg

 

Now compare it to the next image from a hard drive where how fast files transfer depends on their location on the drive.

hdtune-seagate-1tb.jpg

 

Notice the difference in access time and transfer rate. 0.1 ms vs 14.0 ms this is one reason they are faster.

 

Both drives were in the same computer and hooked up to SATA II ports.

 

I hope this helps

Roger


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#7 tssdan

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Posted 21 August 2013 - 06:00 PM

 

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! :)

D

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:

Quote
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.

 

 

You are the best person in the history of the world. Thank you so much for your time. You know EVERYTHING about computers. Thank you so flipping much!!!!!!!!! :)



#8 tssdan

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Posted 21 August 2013 - 06:02 PM

And to answer the question SSD is generally SATA 1, SATA II or SATA III with a very few IDE versions. The Speed of a SSD comes about due to its having no moving parts. Thus fragmentation does not affect it as any location can be accessed just as fast as there is no waiting for the platter to come around or the heads to change tracks.

 

This image shows that the transfer rate is basically flat

128-hdtune-ssd.jpg

 

Now compare it to the next image from a hard drive where how fast files transfer depends on their location on the drive.

hdtune-seagate-1tb.jpg

 

Notice the difference in access time and transfer rate. 0.1 ms vs 14.0 ms this is one reason they are faster.

 

Both drives were in the same computer and hooked up to SATA II ports.

 

I hope this helps

Roger

 

Thank you so much for your expertise, Roger! I always new SSDs were faster because of no moving parts, but I didn't exactly know why. Thanks to you, I know exactly why they are so much more efficient. :)

 

THANK YOU! :)



#9 smax013

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Posted 23 August 2013 - 04:18 PM

You are the best person in the history of the world. Thank you so much for your time. You know EVERYTHING about computers. Thank you so flipping much!!!!!!!!! :)


Glad to help.

And while I might know quite a bit about computers, I DEFINITELY do not know everything. I might be somewhere between having my knowledge of computers being a handful of sand or maybe a bucketful of sand when compared to a whole beach of sand.




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