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What to understand re: USB 3.0 hub

I have an HP Envy 17 laptop that has only 1 USB 3.0 port.  I have 1 USB 3.0 drive and about 8 USB 2 drives/devices plugged into a USB 2.0 hub.

I want to buy a USB 3.0 hub and another USB 3.0 drive.

What do I need to understand to make the best choice?

e.g. It seems that for some USB hubs, the ports share the bandwidth of the USB 3.0 host (e.g. SIIG 4-port USB 3.0 Hub Review) - that wouldn't please me as I am planning on connecting two USB 3.0 drives and the 2.0 hub to the 3.0 hub.

Another gotcha: Upon bootup or reboot, the Envy bios seems to do extensive disk validation on all connected USB drives that (as best as I can explain) have not received a "disconnect" or "power-off" signal.  To better explain:
1)      If the external USB drives are dormant, I only see the BIOS “Press the ESC Key for Startup Menu” at bootup for less than 1 second (which is how I have configured it).  This scenario is common if my laptop was powered off overnight and then I turn it on the next day.
2)      If the external USB drives have only begun to spin up, then “Press the ESC Key for Startup Menu” only displays for about 5 seconds.  This scenario happens if, e.g., I power-on per Scenario 1 above, hit ESC to mess with the BIOS and reboot within maybe 5 seconds.  Upon reboot, the delay is now 5 seconds (it seems because the USB drives are still spinning up)
3)      If the external USB drives are fully up and running (i.e. they have had enough time to fully spin up), then “Press the ESC Key for Startup Menu” displays for 45 seconds.  This scenario happens during all reboots from Windows (i.e. all USB drives were spun up and active before the reboot)

The only way I have found to eliminate the bootup delay is to unplug the power to the USB hub for a moment and plug it back in.  Then I can boot/reboot the laptop without delay.

I mention this "gotcha" because I am hoping that there may be a spec or feature whereby the USB 3.0 hub will send some type of "reset" signal to the connected USB drives upon reboot (i.e. the equivalent of unplugging the power to the hub momentarily) so that I won't face a 45 second delay at bootup (I am not too keen on unplugging/plugging in the hub power every time I reboot!)

Thanks for your help-
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SAbboushi
Asked:
SAbboushi
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2 Solutions
 
☠ MASQ ☠Commented:
Now this may sound a stupid question but what are you hoping to gain from this? You will still only have one USB 3 connection but you will be splitting it's bandwidth.  If you connect multiple storage devices to the hub then each will need a share of the bandwidth for read and write processes.  You won't see USB 3 transfer speeds.
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SAbboushiAuthor Commented:
Thanks - not a stupid question at all -- (maybe MINE was the stupid question!)

The reviewer in the link above stated that the CON (i.e. negative) of the hub he reviewed is "Four ports share the bandwidth of one USB 3.0 host".

If what YOU are saying is true, then I would argue that the review was misleading: I understand you to mean that any devices connected to a USB hub (regardless if 2.0 or 3.0) will share the bandwidth of the host USB port -- that this is the NATURE of USB and has nothing to do with the hub.  Is that correct?
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☠ MASQ ☠Commented:
Think about how the data moves around the system.
With USB 3 you have a super fast connection directly to the system board.
In a desktop you plug into the PCI-E bus.  The laptop works the same way but you only have the one root hub, everything that come off of that only shares the resource of the root hub.  If you want another root hub on a desktop you just plu another card into the system board, on a laptop you're such, you don't have that ability to expand, so your 4 port hub shares the root hub 4 ways (8 if you are using I/O movement between those ports) so you have four ports that work at best at USB3 divided by devices connected which is faster that USB 2 split the same number of ways but not 4 x  USB 3.0 maximum.
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aleghartCommented:
I have a SIIG 7-port hub (4x2.0, 3x3.0) attached to my laptop.  It boots up normally.  I generally have a Thermaltake USB 3.0 -> SATA drive dock attached, with anything from a 250GB-2TB installed.  I also use a portable 1TB USB 3.0 HDD.

The 1TB HDD @5900rpm is not quite as fast as my 500GB eSATA portable drive @7200rpm.  Neither are as fast as a 3.5" HDD in the dock.  All three are not as fast as transferring to a file server over the network with a fast(ish) RAID.

I use the USB 3.0 drive for storing Photoshop projects (backups), and as swap drive space to prevent my laptop from choking on large Photoshop files.  While the USB port is being used for swap (3.5" HDD), the portable drive is only idling.  When I'm backing up files or restoring from the portable drive, the swap drive is idling.  I don't see the conflict.

Now, if you are transferring files from one drive to the other...maybe you'd see a performance hit by sharing the  same USB port.  Let's try a 5GB single file:

D->A = 112MB/sec, down to 78MB/sec = 5900rpm USB3 to 7200rpm USB3 (3.5") sharing same USB3 hub/port
A->D = 121MB/sec, down to 63MB/sec

D->C = 134MB/sec, down to 57MB/sec =5900rpm USB3 to internal 7200rpm SATA
C->D = 116MB/sec, down to 60MB/sec

A->C = 123MB/sec, down to 66MB/sec =7200rpm USB3 to internal 7200rpm SATA
C->A = 64MB/sec, down to 59MB/sec


I think that even the slowest speeds (sharing the same USB3 port) are generally faster than writing to my internal 7200rpm drive.

In any case, do you need more than 60MB/sec?  That 5GB file moved in less than 90 seconds in all scenarios.

What kind of speeds are you looking for?  Perhaps a fast network-based store is called for.
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aleghartCommented:
Sorry...the starting speed is always high due to caching on the drives.  The lower speed usually comes sometime during the last 1/4 of the transfer.  IIRC, these drives have 32MB cache on them.
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SAbboushiAuthor Commented:
thanks aleghard - Am confused about your numbers:
1) D->C = 134MB/sec.  I have read that the USB3 transfer speed is 600MB/sec.  And if so, why is your throughput nowhere near that?  I assume your internal 7200RPM SATA is SATA 600 (600MB transfer speed), so what would prevent somewhere in the neighborhood of 600MB transfer speed between the two?


MASQUERAID: OK - my laptop has 4 USB ports.  I also believe it has 3 USB Root Hubs according to device manager:
1) INTEL(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C26
2) INTEL(R) 6 Series/C200 Series Chipset Family USB Enhanced Host Controller - 1C2D
3) Renesas Electronics USB 3.0 Root Controller


with their corresponding:
1) USB Root Hub
2) USB Root Hub
3) Renesas Electronics USB 3.0 Root Hub

1 of the USB ports is USB 3.0
1 port is eSATA/USB 2.0 (I believe that means it is eSATAp)
2 ports are USB 2.0

I suspect that one of the USB Root Hubs is for the eSTATp port and the other is for the 2 USB 2.0 ports - is there any way for me to confirm?

So if I understand correctly, this means I should be able to reach transfer speeds of:

300MB/s using eSATAp (or 600MB/s if it is eSATA 6Gb compliant - any way for me to confirm?)
 
600MB/s using USB 3.0

60MB/s shared between the 2 USB 2.0 ports

So if my understanding is correct, I should buy a SATA III drive for the eSATAp port to maximize my transfer speeds instead of buying another USB3 drive where 2 USB3 drives now share the USB3 port?
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aleghartCommented:
>so what would prevent somewhere in the neighborhood of 600MB transfer speed between the two?

Basic physics.  A bus can transfer at near theoretical speed.  Rotating platters can only go so fast.  7200rpm drives are limited by the cache, controller, OS, and rotational speed.  10K rpm drives (all others aspects equal) should be faster.  15K rpm drives even faster.

Remove the physical aspects, like an SSD, and you will find far faster speeds.

C->A = 65MB/sec, down to 58MB/sec = internal 7200rpm SATA to external SSD

A->B = 232MB/sec, down to 35MB/sec = SSD(USB3) to SSD(USB2)
A->B = 226MB/sec, down to 128MB/sec = SSD(USB3) to SSD(eSATA)

So, the limiting factor in C->A was the rotational speed of the internal 7200rpm drive.
The limiting factor in A->B over USB2 was the USB2, seen by:
A->B with eSATA instead of USB2 (with the same exact drives and enclosures) is more than 4x the speed.

NEVER use published specs as a basis for maximum speed.  They are just specs...nothing to do with real life.
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aleghartCommented:
Sorry, I ripped apart my USB3 portable drive...and found that the interface is permanently attached to the drive.  So, I can't pop my SSD in there to test SSD->SSD over USB3.
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SAbboushiAuthor Commented:
Thanks - no worries.  I appreciate that you tried to offer such a complete response!

Seems clear that I will get the best throughput transfering between USB3 and eSATA since each has its own USB controller.

Thanks - I appreciate everyone's help.

With Regards-
Sam
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aleghartCommented:
USB3 to USB3 is fine, even on the same hub...if you are using rotating disks, the bus will be far faster than the drives themselves.

If using SSD, my eSATA ports are only 3Gb.  But @ theoretical 300MB/sec, that surpasses the write speed of my SSD.

My point is, if you have it already, eSATA is fine...but you need to provide power to the drive.  If you have USB3 external drives, then the power is over the USB cable, so your clutter (and carrying requirements) will be reduced.
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☠ MASQ ☠Commented:
If you really have eSATAp then you won't need external power but it's much more likely your laptop only has eSATA
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SAbboushiAuthor Commented:
>> USB3 to USB3 is fine, even on the same hub...if you are using rotating disks, the bus will be far faster than the drives themselves.

so do you think getting a USB3 hub and plugging USB3 drives into the hub will get me higher throughput than USB3 to eSATA (mechanical drives, not SSD)?

>> If you really have eSATAp then you won't need external power but it's much more likely your laptop only has eSATA
Is there a way for me to tell?
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aleghartCommented:
USB3 to USB3 on the same hub exceeded the speed of the hard drives.  Going to eSATA won't make a difference.
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SAbboushiAuthor Commented:
Thanks!
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