USB 3.0 HDD Dock that supports 4TB drives

Started Mar 29, 2013 | Discussions
Sean Nelson
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USB 3.0 HDD Dock that supports 4TB drives
Mar 29, 2013

I wanted to post this because I found it rather difficult to confirm whether or not various USB HDD docks supported 4TB drives or not.  I had an existing USB 3.0 HDD dock (a VanTech "NexStar" dock) which did not work with a new 4TB I bought, so needed a new one.   Based on the manufacture's claim that it had been tested with 4TB drives, I decided to buy a StarTech SATDOCKU3E dock from Amazon.ca:

I can confirm that this dock works without any issues with my Seagate 5400rpm 4TB drive (ST4000DM0000).   Not only that, but it recognized and works with the NTFS volume I created when the drive was connected to one of my internal SATA ports.   Limitations in the maximum logical block number supported by the USB mass storage protocol mean that many USB controllers have to "fake" 4TB volumes by pretending they're 4K block size devices.   The ones that do this "break" the file system when you move the drive between the dock and an internal SATA port because the internal SATA ports don't do this.

I was surprised to find that the internally-formatted volume works, and I'm still not quite sure why.   But I'm very happy to find that it does, and I wanted to pass the info on to other folks who might also be looking for an external dock for drives that are larger than 2TB.

Jim Cockfield
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Asmedia ASM1051
In reply to Sean Nelson, Mar 29, 2013

Their .pdf doc with tech specs shows that it's using an Asmedia ASM1051 bridge chipset.

http://www.startech.com/media/products/SATDOCKU3E/PDFs/SATDOCKU3E_Datasheet.pdf

That's a pretty good chipset by most accounts.  But, you're only going to get SATA II speeds to a drive.   More about it here:

http://www.asmedia.com.tw/eng/e_show_products.php?cate_index=97&item=90

It was launched in 2010, and you can find some videos about it online showing throughput.  For example, watch the video in this article and you'll see how it performs.   They also have benchmarks on the screens showing the improvement you'd get with the ASM1051E (versus standard ASM1051), since the ASM1051E supports SATA III, and the ASM1051 doesn't (which is why the speed with an SSD is maxing out at under 300MB/Second with the ASM1051, and they're showing faster speeds with the ASM1051E).

http://www.tweaktown.com/news/14696/asmedia_asm1051_usb_3_0_controller_shows_actual_10x_increase_over_usb_2_0/index.html

IOW, even if using an SSD capable of faster speeds in it, you're probably going to max out at just under 300MB/Second with an enclosure using the ASM1051.

That's a common issue with most of the USB 3.0 enclosures and bays now.   Of course, that's still a dramatic improvement over USB 2.0 enclosures (as you'll probably see speeds close to 10 times as fast with the one you bought via USB 3.0).

But, very few enclosures are using a bridge chipset capable of faster SATA III bus speeds yet (for example, the ASM1051E or one of their other newer bridge chipsets that support SATA III) .

IOW, even though they have bridge chipsets that support SATA III (like the ASM1051E), it's tough to find an enclosure that uses one of those SATA III capable USB 3.0 to SATA III bridge chipsets.  I spent some time looking at feedback about enclosures online not long ago, and was frustrated that I couldn't find one with reported speeds greater than 300MB/Second with one using an SSD that's capable of faster speeds.   My guess is that the cost difference between the ASM1051and ASM1051E (or one of the other chipsets supporting SATA III) is too great for most enclosure manufacturers to switch to it, since most users are going to use an Enclosure or Docking station with something other than the fastest SSDs anyway.

Of course, that's not an issue unless you wanted something allowing more than 300MB/Second via a USB 3.0 connection to an external SSD with faster speeds.

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JimC
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Jim Cockfield
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But, much faster than the JMicron chipsets
In reply to Jim Cockfield, Mar 29, 2013

But, from reports I've seen that ASM1051 is *much* faster than the JMicron bridge chipsets that a lot of other docking stations use, even if the bus speed to the SATA drive is limited to SATA II speeds.

Of course, enclosure makers like to say SATA I/II/III support, even though the SATA bus speed is limited to SATA II (just because they're SATA III Compatible doesn't mean you get SATA III speed). 

Now, I have seen some multi-bay enclosures making use of some of the Asmedia SATA III capable bridge chipsets.

But, for the smaller enclosures, it's tough to find one using anything faster than the Asmedia ASM1051.   Not a big deal though, unless you plan on buying something like a Samsung 840 Pro and want max throughput to it (as you'll probably max out at under 300MB/Second with an enclosure like the one you bought, which is still *great* speed compared to most enclosures).

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Ho72
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Re: But, much faster than the JMicron chipsets
In reply to Jim Cockfield, Mar 29, 2013

Jim Cockfield wrote:

But, from reports I've seen that ASM1051 is *much* faster than the JMicron bridge chipsets that a lot of other docking stations use, even if the bus speed to the SATA drive is limited to SATA II speeds.

JMicron tends to be a lower tier entity. Slow speeds, spotty connectivity and data corruption are just some of the woes they've brought to the table in the past.

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Sean Nelson
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Re: Asmedia ASM1051
In reply to Jim Cockfield, Mar 29, 2013

Jim Cockfield wrote:

But, you're only going to get SATA II speeds to a drive.

Not an issue for me, I only use this for hard drives (backups and archives).

Interestingly, when doing a full format of the drive in the dock the write rate topped out at 104 MByte/sec, and was flat at that rate for about 80% of the drive.  That's well under the drive's sustained throughput spec, so there does seem to be a performance bottleneck somewhere.   It's just as likely to be in my add-on PCIe to USB 3.0 adapter (which uses an NEC chipset) as in the dock, though, so I wouldn't discount the dock based on that.

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Sean Nelson
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Re: Asmedia ASM1051
In reply to Sean Nelson, Mar 30, 2013

Sean Nelson wrote:

Interestingly, when doing a full format of the drive in the dock the write rate topped out at 104 MByte/sec, and was flat at that rate for about 80% of the drive.

Update - now that the drive has been formatted and I've copied files over to it, I'm seeing transfer rates of close to 150MByte/sec.   So whatever the issue was seems only to be related to formatting.

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malch
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Re: Asmedia ASM1051
In reply to Sean Nelson, Mar 30, 2013

Sean Nelson wrote:

Update - now that the drive has been formatted and I've copied files over to it, I'm seeing transfer rates of close to 150MByte/sec.

That's pretty nifty especially if it's for a assortment of file sizes (including some smallish ones).

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