Why usb3 raid0 are slower than thunderbolt? at DVinfo.net

Marcello Mazzilli · October 23rd, 2012, 05:23 PM

... I mean.. I know usb3 is 500 mb per secpnd and thunderbolt is double... But i don't understand why the disls inside would go slower. The speed of a 2x disks in raid0 should be roughly double of the single 7200 disk.. Around 220 mb second in read.
Take LaCie for example... The usb3 model is 230 while the thunderbolt model is 320.... What has the transfer standard, the cable, the port... Has to do with it... They are both standards way faster than the raid itself
I don't understand

Randall Leong · October 24th, 2012, 11:50 AM

That has more to do with the maximum sustained (sequential) throughput of the two interfaces. You see, the 500 MB/s throughput of the USB 3.0 interface is the burst throughput, not the sustained throughput. On most interfaces whose throughput is shared between multiple devices such as USB, the maximum sustained throughput per device is only about 30% to 60% of the maximum burst throughput. This means that depending on the controller chips used, USB 3.0's maximum sustained throughput is between 150 MB/s and 300 MB/s (and since native USB 3.0 support on motherboard chipsets is still relatively new and relatively rare, most systems will have USB 3.0 sequential throughput that's closer to 200 MB/s or even less).

Marcello Mazzilli · October 24th, 2012, 11:53 AM

Thanks...
And.. any idea how the LaCie thunderbolt can obtain 327 Mb/sec if a single disk on the saga connector inside the case gets 110Mb or so?
M

October 23rd, 2012, 05:23 PM	#1
Marcello Mazzilli Major Player Join Date: Apr 2009 Location: ITALIA Posts: 416	Why usb3 raid0 are slower than thunderbolt? ... I mean.. I know usb3 is 500 mb per secpnd and thunderbolt is double... But i don't understand why the disls inside would go slower. The speed of a 2x disks in raid0 should be roughly double of the single 7200 disk.. Around 220 mb second in read. Take LaCie for example... The usb3 model is 230 while the thunderbolt model is 320.... What has the transfer standard, the cable, the port... Has to do with it... They are both standards way faster than the raid itself I don't understand

October 24th, 2012, 11:50 AM	#2
Randall Leong Major Player Join Date: Nov 2009 Location: Melrose Park, Illinois, USA Posts: 936	Re: Why usb3 raid0 are slower than thunderbolt? That has more to do with the maximum sustained (sequential) throughput of the two interfaces. You see, the 500 MB/s throughput of the USB 3.0 interface is the burst throughput, not the sustained throughput. On most interfaces whose throughput is shared between multiple devices such as USB, the maximum sustained throughput per device is only about 30% to 60% of the maximum burst throughput. This means that depending on the controller chips used, USB 3.0's maximum sustained throughput is between 150 MB/s and 300 MB/s (and since native USB 3.0 support on motherboard chipsets is still relatively new and relatively rare, most systems will have USB 3.0 sequential throughput that's closer to 200 MB/s or even less).

October 24th, 2012, 11:53 AM	#3
Marcello Mazzilli Major Player Join Date: Apr 2009 Location: ITALIA Posts: 416	Re: Why usb3 raid0 are slower than thunderbolt? Thanks... And.. any idea how the LaCie thunderbolt can obtain 327 Mb/sec if a single disk on the saga connector inside the case gets 110Mb or so? M