Practical performance of ExpressCard?

[cgilley]

I'm looking at the ExpressCard as a reasonably fast backup device. I've found Firewire 4* and USB 2.0 to be unacceptably slow. Testing these, the practical throughput rate from disk through the USB or FireWire to the other disk is not even close to theoretically. I know it's a systems issue.

now, does anyone use an ExpressCard SATA 2 interface to talk to an external SATA 2? How well does it work and do you have any reasonable bandwidth numbers? Assume we have a dual core processor.

 

[dwellman]

I use ExpressCard to eSATA and it is as fast as could be expected.

 

[cgilley]

"expected" What does that mean to you? Just curious.

I have a 480Mbps firewire in my laptop, theoretically, I should get something like 40MB/sec transfer rate. It has never even approached that.

I read an article on a guy that used the ExpressCard adapter to connect to two 7200RPM SATA2 external drives. Even with two transfers going, he was able to sustain 65MB/sec per channel across the interface. Assuming I'm backing up a 160GB hard drive, that equates to about 41 minutes - I can live with that.

 

[dwellman]

Expected: eSATA gives you pretty much the same as SATA, which is what most people expect.

 

[cgilley]

fair enough. thanks

 

[piratepast40]

The expresscard interface is the same as USB so the data transfer speeds are the same.

 

[dwellman]

What? Oh, no. You are confused. The ExpressCard interface can utilize either PCIe or USB, depending on the card. An expresscard to eSATA should use the PCIe interface providing a theoretical 2.5 Gbps vs USB 2.0's 480 Mbps.

 

[cjl]

I'm surprised Firewire is slow - I run an external Seagate 750GB off of firewire on my laptop, and get 37MB/s easy.

Expresscard to E-sata should be faster though, if yours isn't performing up to par.

 

[piratepast40]

What? Oh, no. You are confused. The ExpressCard interface can utilize either PCIe or USB, depending on the card. An expresscard to eSATA should use the PCIe interface providing a theoretical 2.5 Gbps vs USB 2.0's 480 Mbps.

I was mistaken and you are correct in that it supports PCI express OR USB.

Sorry (puts on dunce cap and goes to sit in the corner)

 

[piratepast40]

What I was refering to was the limitation of the interface to a single lane and hence the slow speed. The new PCIe 2 interface with XGP sounds tremendously exciting.