В Tue, 4 Sep 2012 23:55:57 +0400
Anatoly <anat...@kazanfieldhockey.ru> пишет:

> Hello,
> I have a problem with my new 32G pendrive:
> da1: <JetFlash Transcend 32GB 8.07> Removable Direct Access SCSI-2
> device da1: 40.000MB/s transfers
> da1: 30640MB (62750720 512 byte sectors: 255H 63S/T 3906C)
> I'm using fat32 partition on it.
> To make problem occur I can do following things:
> 1) write a file about 5MB in size on that partition
> 2) unmount
> 3) unplug pendrive (so it loses power)
> 4) plug it again
> 5) mount
> Now I can see that the end of file is corrupted.
> Poblem never occurs when I do:
> 1) write a file about 5MB in size on that partition
> 2) unmount
> 3) mount
> Also, problem doesn't occur if I'll wait for more than ~10 minutes
> before unplugging pendrive.
> So it seems to me that this pendrive has internal write cache in RAM
> that needs to be flushed before pendrive loses power.
> Problem never occurs with Windows. As I click "remove", windows
> somehow "correctly shutdowns" pendrive so it's LED goes off (Unlike
> if i just unmount, when the LED stays on) 
> What can I do to get cache flushed before unpugging, turn that write
> cache off, or any other suggestions?
> I've tried camcontrol stop and camcontrol eject with no
> success
> I using FreeBSD 7.3 with generic kernel here

I've found solution:
that 'upower' utility allows to suspend pendrive, and I get cache
flushed (And LED goes off):
upower /dev/usb0 2 suspend
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