Blackmagic Forum

I'm planning on installing two USB-C type 10Gbps ports on my 5.1 Mac Pro. I can buy a single USB-C connected CFast card reader that has TWO built in card slots (The Wise WA-CRD05OR) I can buy TWO CFast USB-C card readers (The Wise WA-CR03) that have only ONE slot each and plug each reader into it's own port.

When reading two cards simultaneously, which scenario will be faster? I know it might be logical to assume that two dedicated readers might be faster, but the actual read speed of the CFast card itself (In my case the Transcend CFX650 256gb) might hit it's limit with the dual slot reader alone. I'd prefer having just the one dual slot reader if it's not going to make a difference. My goal is to be able to edit directly from two cards without having to download the media. Any thoughts? Thanks!

A single USB-C port should have enough bandwidth for two simultaneous reads. The question is how good is the bandwidth of the 2 port reader? I have an USB3 multiport reader from Lexar, which drops total speed significantly when reading from more than one card at a time.

You might have a look at the Sonnet Cfast reader:
http://www.sonnettech.com/product/sf3-c ... eader.html

Any 2-stream copy (be it 2-slot reader or 2 independent readers) will be slower than a single reader just because the receiving side is a HDD which would need to move heads to access data. Moreover, it means that the both copy files would be fragmented (remember defrag programs in OS-like abomination named Windows?) and the access would be even slower.

Of course the speed record would be if you alternatively copy files from both cards according to their names but I just cannot imagine how to do it except by writing the special program for the purpose which reads data in parallel and then writes them sequentially.

Sorry, but who transfers his footage from a CFast card to a single HDD?
I have a RAID5 of 8 disks and the raid controller does a very good job at sustaining the speed. I get around 850MB/s for read and write. The controller has on-board cache and is optimized for data stream handling, the OS uses RAM caching to optimize write speed.

I can copy from a CFast reader, a CF reader and over GBit network simultaneously to my 35TB RAID without a big performance hit.

And if you are using latest M2 SSDs there is even less a problem with that.

Benton, the answer may depend upon the computer you are using. If you have two separate USB data controllers and plug each separate card reader into the separate controllers, then two readers will outperform a single reader I suspect.


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Robert Niessner wrote:A single USB-C port should have enough bandwidth for two simultaneous reads. The question is how good is the bandwidth of the 2 port reader? I have an USB3 multiport reader from Lexar, which drops total speed significantly when reading from more than one card at a time.

You might have a look at the Sonnet Cfast reader:
http://www.sonnettech.com/product/sf3-c ... eader.html

Thanks for your input Robert. The Sonnet reader looks great, but at $200 I'm hoping that the two slot $79 Wise USB-C reader will do the trick. I suppose I'll have to try it and see if it delivers slower read times when simultaneously reading two cards. If it slows down, I can always try a second single slot reader for $57 and still spend less than the Sonnet. At any rate it's nice that my aging, but nearly maxed out, 2009 5.1 Mac Pro still has higher speed options that become available for it!

rick.lang wrote:Benton, the answer may depend upon the computer you are using. If you have two separate USB data controllers and plug each separate card reader into the separate controllers, then two readers will outperform a single reader I suspect.


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You might very well be correct Rick. I think I'm just going to have to take the plunge and see what works best. Thanks!

What a scientist! Nothing as convincing as an empirical experiment. You need to be sure that separate data controllers are being used. With Apple they usually have four ports sharing two data controllers. By trying different ports, you will likely see a combination of USB ports that works best.


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