Data transfer speeds from one drive to another in dual 3.5" hdd enclosure

[Ksyder]

I just picked up one of these today:
http://www.microcenter.com/single_product_results.phtml?product_id=0363770

And I have it running with 2 x 2Tb 5400 rpm Samsung drives as seen here:
http://www.newegg.com/Product/Produc...82E16822152245

This device shows up as 2 separate drives within Windows even though it is connected to my laptop's USB 3.0 port through a single cable.

Right now with a large sequential transfer from one drive to the other within the enclosure I'm getting about 64 MB/sec or so transfer speed. My question is, does the data have to travel through the usb bus back to the laptop or is the controller smart enough to just transfer from drive to drive within the circuitry of the usb enclosure itself.

Essentially I'm wondering, is the bottleneck the speed of these slower, 5400 drives or is is the usb bus on the laptop that is holding it back? I'm thinking of trying it with a couple of the faster 1TB 7200 RPM Samsung HD103SJ drives I have laying around and see what the results are with that. With these 1TB drives I used to get 100-110 MB/sec through the internal sata ports on my desktop but I have since switched to using a laptop as my primary machine so I'm looking for a good backup solution that is easier to deal with regarding the laptop.

Thanks everyone for any insights into this.

 

[Coup27]

Whether the data is staying within the DAS box or going back and forth over USB3, the write limit will be caused by the drives.

I've used in the past a WD Passport Essential on my mobo which has USB3. Those are 5400rpm drives which reads and writes maxed out at 70mb/sec according to CrystalDiskMark.

 

[nanaki333]

are you copying really large files, or a bunch of small ones? if it's a lot of small ones you're not going to get the maximum speed.

 

[Ksyder]

are you copying really large files, or a bunch of small ones? if it's a lot of small ones you're not going to get the maximum speed.

Its all large files... but heck 60-65 MB/sec is really not bad... especially over usb on a laptop. I used to get around 30 MB/s or so on usb 2.0 external drives.

 

[Coup27]

Not sure if you have considered this but if the laptop itself has a 5400rpm drive in it then everything you transfer to the DAS box will be stuck at around 70mb/sec.

 

[Ksyder]

Not sure if you have considered this but if the laptop itself has a 5400rpm drive in it then everything you transfer to the DAS box will be stuck at around 70mb/sec.

Yep, I am aware of that, its definitely a tradeoff of hdd speed on a laptop to have the convenience.

It did achieve 110 MB or so when I was copying something last night, and I realized that some of the files are somewhat smaller as there was tv show episodes which are smaller relatively speaking.

I did think of a way to see what effect the usb bus has on the transfer drive to drive within the enclosure- just use a usb 2.0 port with a standard usb a-b cable and see if the transfer speed drops dramatically. I'll probably try that this morning.

 

[Coup27]

Yeah good idea, be interesting to see if it does have to go back and forth over USB or not.

 

[Ksyder]

just tried using usb 2.0 only, and the speed dropped down to less than 30 MB/s transferring video files... but then back up over 60 with a usb 3.0 cable.... now to get a USB 3 cable longer than 3 feet.

So I guess its safe to say that the data does travel through the usb bus on the laptop in this scenario.

 

[Coup27]

Now all you need is an SSD for your laptop and some decent 7200rpm HDD's for the DAS box and you'll be zipping along at 130mb/sec

 

[Ksyder]

Good idea coup27... but lol if only I had unlimited $$$ to work with I'd be all over that. So many different possibilities with NAS and other types of storage but I was trying to keep the cost low and the setup flexible. Honestly I'd like to use a NAS but I'm afraid of the performance being poor over the network since I can't upgrade the entire network to gigabit, etc.

This situation is similar to awhile back my buddies told me if you hook a gigabit switch to a router with only fast ethernet, you would still get gigabit transfers between all of the gigabit nic-equipped PC's that are hooked up to that switch despite dhcp and everything else handled by the slower router. I never have tried it but I believe it works. I was kind of hoping it would be a similar type of scenario with the hard drives despite the link to the usb bus. Unfortunately I am no computer engineer so I can only speculate on what is happening.

 

[Coup27]

If you had 10 PCs with gig nic's connected to a gig switch with a fast router connected to the switch then your buddy is correct. All transfers between the PCs would happen at gig speeds but any external information from the web would come in at fast speeds. Largely academic though because fast ethernet is 12.5MB/sec, I can't remember the last time I got more than 1.5MB/sec sustained from a web server.

I don't know what setup you have there but you could have got small 4 way gig switch, connected a NAS and the PCS to it and the router into it and replicate the above.

 

[murphyc]

I have a WD Caviar Black HDD in my laptop and regularly get 120+MB/s transfers. So I'm not understanding what disks these are, with USB 3.0, that are dragging along at 1/2 or less of this. Even the desktop Caviar Green with a 32MB cache, 5400RPM rotation speed, and 500GB capacity push 110MB/s. NTFS is sorta brain dead but even it doesn't have 30%+ overhead.