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Speed of 2.5" HD: External USB3 vs. Internal SATA

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  • Hard Drives
  • Performance
  • SATA
  • Western Digital
  • Storage
Last response: in Storage
January 27, 2013 10:28:51 AM

I am trying to find information on the relative "performance hit" which would be taken by using an external USB 3 drive instead of a traditional internal SATA HD.

In order to try to evaluate the speed difference, I have looked at the performance charts for the 2.5" external USB3 drive I would be using (WD My Passport) and compared it to the internal SATA drive I would use (WD Scorpio Black).

The Read Throughput Average is 83.5MB/s for external against 97.99MB/s for internal.

The Write Throughput Average is 83.3MB/s for external against 93.42MB/s for internal.


The difference in these figures is approximately 20%, am I right in thinking that the actual difference in performance would only be around 20%? I am aware that I am overlooking factors such as read access time, performance reading smaller files etc, does anyone know the relative difference these would make?

The reason why I ask is because I am building a system using Akasa Euler case, this case only has room for 1 internal 2.5" drive. The MOBO does support mSATA, I was originally planning on going with an mSATA 256GB SSD along with the 750GB WD Scorpio Black.

However the mSATA is only 3.0GBps, so I would sacrifice SSD speed against using a Samsung 840 Series 250GB SSD (can use SATA 6.0GBps). However using a traditional SSD would mean there is no space for the 750GB WD, meaning I would have to rely on an external USB 3.0 drive. :( 

What would other people choose to do in this situation? Changing the case is not an option, I am hellbent on using this one.

More about : speed external usb3 internal sata

a c 117 G Storage
January 27, 2013 1:20:17 PM

While the numbers might seem fairly close, in reality there would be a larger performance difference than that in real-world scenario's.
USB and SATA controllers are optimized for different workloads.

Running a test right now on a USB3 external drive (WD My Passport 500GB) and a Seagate Barracuda 1TB 7200RPM drive, will post the Crystal Disk results at the bottom. The test is a bit biased toward the internal drive since its 3.5" and isnt as full as the external, but even so the performance difference is fairly large.

That being said, if all your storing on this drive is music, movies and just general files. Not running games/programs or using it as a render output drive, then performance shouldn't matter really.

My suggestion, see if you can actually fit the drive in there anyway. Might require a bit of thinking and some modifications to the case, but there must be a way.
Or take advantage of the e-SATA port that is most likely on the back of the mobo. That will allow you to plug in SATA devices as long as you have some external method of giving it power.

EDIT: Forgot to actually post the results :p 
Left is the internal drive (Seagate Barracuda 1TB 64MB cache 7200RPM, on a SATAIII connection) and the right is the external (WD My Passport 500GB USB3, connected by USB3).
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June 26, 2015 3:01:25 AM

This can't be true. I have a WD passport 1TB and I managed to actually download a torrent with a speed of over 50 MBps directly onto it and WD is supposed to be better than Seagate too. I think this may vary depending on your system and your USB drivers.
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a b G Storage
June 26, 2015 4:21:53 AM

Sorry, followed a grave digger. DELETE.
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a c 464 G Storage
June 26, 2015 9:19:53 AM

The performance numbers posted by manofchalk above look very much like performance of a USB2 system, not USB3. I wonder if the USB port on the computer in use really was USB3? To get USB3 performance, BOTH the computer's port and the external device need to be USB3.

The suggestion of eSATA has merit, although some changes to your plans would be involved. First of all, the 2½" external HDD you specified (WD My Passport 750 GB - I did not find that size on the WD website) does not have an eSATA interface. And ALL eSATA systems (except for non-standard eSATAp systems) do not draw any power from the host computer, but require their own power supply module that plugs into the wall. However, that also opens the possibility of using a larger HDD, because that wall power supply does not limit the size and speed of the HDD in the enclosure the way that USB ports do. So, you could make your own external hard drive by buying a desktop-size (3½" form factor) HDD that is fast (like a WD black) and larger than 750 GB plus an external enclosure that has a SATA internal interface and an eSATA external interface. Just be sure the eSATA is rated for at least SATA 3.0 Gb/s - you do not need SATA 6.0 Gb/s because no mechanical HDD can exceed the 3.0 spec anyway. However, this would also mean that you need a mobo that has an eSATA 3.0 Gb/s or 6.0 Gb/s port. You have not told us exactly which mobo you plan, although you imply it includes a USB3 port.

In my experience with eSATA, that interface is virtually the same speed as an internal SATA interface.

As another alternative, consider a similar system - enclosure with its own power supply (to avoid power limit of USB3) plus larger HDD, but with a USB3 interface to your computer, if your mobo only has that port. You should get the data transfer rate you want (limited by the HDD's speed, not by the interface) with a larger HDD capacity for a total price probably less than the 750 GB WD My Passport. Plus, that system would not have proprietary coding of data. In fact, these days if you look around for an external enclosure, you often find that they come with two external interfaces - like, for example, eSATA plus USB3 - and you use only one of them at a time.
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August 23, 2015 1:17:05 AM

Cioby said:
This can't be true. I have a WD passport 1TB and I managed to actually download a torrent with a speed of over 50 MBps directly onto it and WD is supposed to be better than Seagate too. I think this may vary depending on your system and your USB drivers.


USB 3.0 controllers are not yet that optimized. Thats why a internal HDD with a max mechanical limit of about 130-150MB can beat it because they use SATA connection, I see alot of extrernal 3.0 drives only speeds are 50-90MB

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Anonymous
November 30, 2015 6:18:51 PM

Quote:
Cioby said:
This can't be true. I have a WD passport 1TB and I managed to actually download a torrent with a speed of over 50 MBps directly onto it and WD is supposed to be better than Seagate too. I think this may vary depending on your system and your USB drivers.

I think you are confusing Mega Bytes and Mega Bits, if you are able to download at 50MBps then you have a 500Mbps internet connection, I doubt that, if true though that must be really nice. :-) I have a 100Mbps connection so I can download 10MBps.

So if it's the case you really have a 50 mega bit connection that mean's you can download at 5 mega bytes per second and that's nothing compared to the 80-160 mega bytes or so a mechanical drive can deal with, an SSD would be over 500, so 100 times as fast as you could download.
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January 14, 2016 5:51:21 AM

Anonymous said:
Quote:
Cioby said:
This can't be true. I have a WD passport 1TB and I managed to actually download a torrent with a speed of over 50 MBps directly onto it and WD is supposed to be better than Seagate too. I think this may vary depending on your system and your USB drivers.

I think you are confusing Mega Bytes and Mega Bits, if you are able to download at 50MBps then you have a 500Mbps internet connection, I doubt that, if true though that must be really nice. :-) I have a 100Mbps connection so I can download 10MBps.

So if it's the case you really have a 50 mega bit connection that mean's you can download at 5 mega bytes per second and that's nothing compared to the 80-160 mega bytes or so a mechanical drive can deal with, an SSD would be over 500, so 100 times as fast as you could download.


What do I look like? A moron? And if you can download with 50 MBps you actually have 400+ Mbps internet speed. I can write to my USB stick with 70-250 MBps. I downloaded directly on my USB 3.0 connected external WD passport with a speed of over 50 MBps easy. I can copy onto my WD passport with speeds of up to 200 MBps.

Note that the maximum speeds are the speeds that usually occur at the beginning of the writing. I've had a 14 GB file copy 7 GB with a speed of 200+ on USB (because it was probably using my cache) and then it started decreasing slowly down to 70 or so.
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April 29, 2016 12:27:07 AM

For me, my external hdd is faster than the internal. First is the internal, and the second is the external hdd.
http://imgur.com/a/gZgJp
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May 22, 2016 10:04:48 AM

Cioby said:
This can't be true. I have a WD passport 1TB and I managed to actually download a torrent with a speed of over 50 MBps directly onto it and WD is supposed to be better than Seagate too. I think this may vary depending on your system and your USB drivers.


But networks speeds are usually given as megabits per second (for example 50 Mbps) whereas the above numbers in the hdd i/o are in megabytes per second. Now, since one byte is 8 bits, that would mean that (according your logic) you could download to that drive of 40 megabytes per second using a 320 megabit connection without anyproblems. So that poster is claiming that his test performed at 6 times the throughput of your connection (50 megabit).
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