Re: Problems with USB disc drives?

On Tue, 30 Jan 2007 20:09:41 GMT, Jim Haynes staggered into the Black
Sun and said:
I have a Gigabank 4GB USB disc. One problem I'm aware of is that
after telling Linux to unmount it

It's spelled "umount". The first n vanished in the 1970s, maybe it's in
with the Bee Gees albums somewhere.

you have to wait some time after the icon goes away before it is safe
to unplug the drive. I know this because

It's explained (or should be explained) in everything that deals with
removable media in Linux. You have to umount a medium before removing
it because writes are cached. Sometimes writes are cached very
aggressively on slow media (floppies, USB 1 devices, ZIP disks, etc.)
You can avoid write-caching by mounting this with -o sync , but that
makes performance suck. The thing that should always work is to umount
it from the command line and wait for umount to return.

Some USB devices (newer iPods) have bits of intelligence in them and
will display "do not disconnect" on their screens while they're plugged
in to a USB port. They do this even if they haven't been mounted. The
cure for this is to rmmod usb-storage && rmmod ehci-hcd , which causes
the device to think it's been gracefully ejected.

Even when I wait there is apt to be trouble. Often after writing the
disc in Linux, there will be corruption in the directory.

What filesystem is on this disk? ("disc" is for optical media.) FAT32
has been supported for aeons. NTFS is still problematic, but ntfs-3g
has worked fine for me. YMMV.

After [the disk] gets corrupted I typically have to format the drive
in Windows and start over.

fdisk, mkdosfs -F32 or mkntfs. No need to partition/mkfs in 'Doze
unless you really want to. Are there any errors/warnings in dmesg about
the USB subsystem? Which kernel version are you using? There's no
mention of a Gigabank anything in the unusual-devs.h file in 2.6.18.3 or
2.6.19.2 kernels.

--
Kimono dragon: found mainly on Pacific islands and atolls, this is the
more dangerous version of the somewhat placid bathrobe gecko.
--jghanc
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
.

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