Confused about partitions and USB storage

mattsavigear

I have a several-in-one card reader on my machine. Right now it comes up as sda and sdb (there are two luns on the device, one for CF and microdrives, the other for SD, SM and so on), as well as the corresponding /dev/sd/c2b0t0u0 and c2b0t0u0.

Now, I can try to mount /dev/sd/c2b0t0u0, which fails as expected, however after the mount attempt, I then have a device for the partition created, /dev/sd/c2b0t0u0p1 (and /dev/sda1), which I can mount.

So, I have a question - is there a way to avoid the initial failed mount attempt which is currently required to cause the partition device to be created? I don't actually want the cards to automount themselves, I just want the partitions to be automatically available to me to manually mount should I insert a card.

In case it's important I'm using ehci_hcd built into my 2.6.7-mm kernel.
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Matt.

"Ninjas aren't dangerous. They're more afraid of you than you are of them." - The Tick.

diastelo · Guru Joined: 23 Feb 2004 Posts: 521

Are you using devfs or udev? Devfs and udev both handle creating devices "dynamically", but they do it in different ways. Udev is the newer and better standard out there right now, while devfs is the tried and true.

Have you tried mounting /dev/sda1 or /dev/sdb1 without waiting for the device to appear? It may be enough to trigger it to work.
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mattsavigear · Posted: Fri Jun 25, 2004 10:12 am Post subject:

Currently devfs (assuming that's the default for a recent Gentoo install), though I might look into udev over the weekend. To be honest, I need to look into these topics anyway - I haven't a clue what the /sys directory is all about and whether that should be useful, or is that actually part of udev?

Time for some research I feel.

Oh, and I tried mounting sda1 and so on before they appear, but it fails.
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Matt.

"Ninjas aren't dangerous. They're more afraid of you than you are of them." - The Tick.

diastelo · Guru Joined: 23 Feb 2004 Posts: 521

/sys is required for udev to work. Having it there without udev installed won't accomplish much, but it won't hurt anything either.

If you want to take the plunge and try udev, Gentoo is an excellent place to try it. There's a system in place that will let you switch between udev and devfs at boot. If you browse through the forums, you might be able to find others who have come up with solutions to your problem with udev. Someone has even kindly created a guide to getting Udev up and running (http://www.gentoo.org/doc/en/udev-guide.xml). Hope this helps.

In the meantime, have you tried putting the card in the reader, then plugging it into the computer? Maybe if the card is already in the device, it will trigger devfs into recognizing the partitions earlier.
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"No question is so difficult to answer as that to which the answer is obvious" -- George Bernard Shaw

mattsavigear · Posted: Mon Jun 28, 2004 8:35 am Post subject:

Well, I've got udev up, and now I'm researching what to actually do with it. I can't plug and unplug the device, BTW, as it's internal.
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Matt.

"Ninjas aren't dangerous. They're more afraid of you than you are of them." - The Tick.

diastelo · Guru Joined: 23 Feb 2004 Posts: 521

Peripherals are so much simpler when they're external. Oh well. In any case then, modify my last suggestion to read "boot your computer with the memory already in the device" and see if that accomplishes anything.

There was this fairly large thread that I've lost track of a while back called "I have udev installed, now what?". I did a quick search for it, and I haven't found it, but I'm a little slow today (Mondays, you know), so feel free to take another look. It might be up your alley.
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"No question is so difficult to answer as that to which the answer is obvious" -- George Bernard Shaw

Decibels · Veteran Joined: 16 Aug 2002 Posts: 1630 Location: U.S.A.

Got Udev working, now what?
https://forums.gentoo.org/viewtopic.php?t=115096&highlight=

Udev Primer
http://webpages.charter.net/decibelshelp/LinuxHelp_UDEVPrimer.html
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