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why no hot-swappable PCIe-readers?

M

malch

macrumors 6502
Original poster
Jan 20, 2008
466
9
Hi there,
I've been hoping to find a fast PCIe express reader, for getting video files from my SxS cards into my Mac Pro, but I've been told it's not possible: the fault, I was just told, lies with the designers of motherboards (both Macs and PCs) that don't allow "the PCIe express interface to be hot swappable".
I don't understand... I have a MacBook Pro that has an ExpressCard slot that allows me to import (and swap) SxS cards. Why can't something like this be built, externally if necessary, for the Mac Pro?
regards,
malch
 
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Yes, you're right about USB-readers, Cindori. I was hoping to find something faster. Of course there might soon be a USB3 version of the USB reader... but nothing that I've heard of yet.
thanks for the note,
malch
 
But this (I followed your second link) wouldn't be hot-swappable, would it?
It looks like other PCIe readers I've checked out, and non of them are hot-swappable.
Is this one, by chance?
malch
 
http://www.sonnettech.com/product/qio.html

qio_0710.jpg


http://www.sonnettech.com/news/ibc2010/index.html

qioe3_composition2.jpg
 
Yes the Qio is gorgeous, but it's $1,000 (when I last checked).
regards, malch
 
Cindori said:
The ExpressCard slots in Macbooks are connected internally via USB, I believe.
Click to expand...
Semantics: MacBooks never had ExpressCard slots, 15" and 17" MacBook Pro's did. The ExpressCard slot in the 15" models has been replaced by the sd card reader which is hooked up to the usb bus. Judging by the fact that a lot of people have very good speeds with ExpressCard ssd's Apple is definitely connecting them to PCIe. Macperformanceguide.com has some benchmarks that show sata-300 speeds which far exceeds usb2.

@malch: I'm not sure if the Mac Pro supports hot-swap. If it doesn't then there is your culprit.
 
malch said:
But this (I followed your second link) wouldn't be hot-swappable, would it?
It looks like other PCIe readers I've checked out, and non of them are hot-swappable.
Is this one, by chance?
malch
Click to expand...

You are not hot-swapping the PCIe module, you are just hot-swapping the Expresscard you insert into the module. It should work.

When talking about hotswap you can't go down the chain of connected modules. I mean if you install, say a PCIe USB controller

brando-pci-e-usb3.jpg


...then of course it is not the same kind of hotswap to hotswap the whole controller (like removing it from the mac pro), as it is to just hotswap a USB connection to it.

hope you follow :)
 
Once again, thank you Cindori, for the info. I'm going to have to read and re-read this a few times. From what I've gathered on a site dedicated to the kind of camera I use (which uses SxS cards), no one knows of a PCI-e reader that works, if you want to switch cards, without first having to power down (re-boot), or by using the device manager to re-scan the hardware (this is a PC thing, I think).
But maybe this one you point to doesn't need to do this... I'll check it out.
regards,
malch
 
O.K., upon further inquiry, this is what I've been told:

"The Express Card interface consists of two interfaces: one USB-port and one PCI-related port.
The USB-port can always be hot swapable.
The PCI-interface that the SxS-cards are using does not hotswap on all computers. This is dependant on the motherboard and BIOS. It seems like all laptops are able to hotswap but most stationary computers are not.
This means that the computer does not see a swapped card until you reboot the computer. Fortunately PC:s have the ability to scan for new hardware without rebooting, using the device manager (as mentioned earlier in this thread). This only adds two mouse clicks to the process of changing cards. On the Mac there does not seem to be any other way than rebooting"

So I think (as a Mac-user) I'm out of luck...
regards,
malch
 
The interface for PCI Express is not really built for hot swapping. Even if the motherboard supported such behavior, you'd be risking a short because some pins would be exposed while others would be connected.

Expresscards deal with this problem by being designed so that either all the pins are connected at once, or none are connected.
 
Well, here's what I've been told:

"the Expresscard specification includes USB and PCI Express x1 which is why laptops are 'hot-swappable'"
and (quoted before):
"The PCI-interface that the SxS-cards are using does not hotswap on all computers. This is dependant on the motherboard and BIOS. It seems like all laptops are able to hotswap but most stationary computers are not"

Anyway... seems I'm stuck with exporting from my SxS cards on my MacBook Pro for the time being.
Thanks all,
malch
 
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