CF Card Images and Linux

discuss PC<>Acorn file transfer issues & the use of FDC, XFER, Omniflop/disk etc.
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sweh
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Re: CF Card Images and Linux

Postby sweh » Sat Apr 19, 2014 8:14 pm

BeebMaster wrote:Well, the old reader only does 1MB/sec in all three slots

Probably so old that it's a USB-1 device.
Rgds
Stephen

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Re: CF Card Images and Linux

Postby BeebMaster » Sat Apr 19, 2014 8:36 pm

Is that with a CF reader in the PC? Or connected via USB?
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Re: CF Card Images and Linux

Postby 1024MAK » Sat Apr 19, 2014 8:41 pm

sweh wrote:
1024MAK wrote:Some USB ports on computers are actually via on-board integrated USB hubs. Sometimes some USB ports are indeed slower.

Mark

A hub isn't really too much of a problem; USB allows for hubs without noticable degradation of speed. Some machines of that age (not common, but some still existed) had some USB-1 ports and some USB-2 ports. 1MB/s is 8Mbit/s which is close to the USB-1 limit (12Mbit/s). USB-2 can go to 480Mbit/s, and I think can sustain 240Mbit/s (35MB/s).

It really sounds like you have 1*USB1 and 2*USB2 ports on that machine.

Yes, that's more or less what I was getting at - the front USB ports may be provided via a USB-1 internal hub.

Mark
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Re: CF Card Images and Linux

Postby BeebMaster » Sat Apr 19, 2014 8:44 pm

I've tried lots of different block sizes, from 1K up to 512MB, the best speed I got was with a 2MB block size, which gave me 10MB/s on the first occasion but 9.9MB/s after that.

Interestingly after I moved the CF reader to the bottom left hand slot, I suddenly got speeds of 1MB/s again. I thought it might be due to using the same terminal window all along, as if too much information was cached or something, so I closed it and opened a new one. I didn't make any difference, so I went back to the right-hand USB port and I was only getting 800K/sec!

I did lsusb which told me the card reader was registered on bus 3, device 5. I unplugged it and waited a while and put it back in the same slot and it came up as bus 1, device 39 and I was back to 9.9MB/s!
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Re: CF Card Images and Linux

Postby BeebMaster » Sat Apr 19, 2014 8:49 pm

Good job I didn't gum up the top left-hand USB slot - I just tried it again, and lsusb showed it as bus 1, device 41, and I get 9.9MB/s!

So it seems like it's what bus the card reader is registered on, not what slot it's in - bus 3 = slow, bus 1 = fast, bus 2 = who knows?

Time for a cup of tea and a hot cross bun!
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Re: CF Card Images and Linux

Postby sweh » Sat Apr 19, 2014 9:07 pm

BeebMaster wrote:I did lsusb which told me the card reader was registered on bus 3, device 5. I unplugged it and waited a while and put it back in the same slot and it came up as bus 1, device 39 and I was back to 9.9MB/s!

That's bizarre. The bus is normally hard-wired. The device number does increment as you insert/remove devices.

I wonder if the ehci and ohci drivers are having a fight on your machine and different ones win at different times!

I wonder what "dmesg" says.

Ah well, at least you have a way of determining if the thing has negotiated a fast-speed connection :-)
Rgds
Stephen


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