how to force my 32G usb pendrive to flush write cache in RAM it has?

[Stanislaw W.]

W dniu 05.09.2012 23:47, Anatoly pisze:
> В Tue, 4 Sep 2012 23:55:57 +0400
> Anatoly <> 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:
> http://lists.freebsd.org/pipermail/freebsd-usb/2008-March/004677.html
> 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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>
To flush cache You can also use sync(8)


Stanislaw.