Re: [PATCH repost 3] [SCSI] Retrieve the Caching mode page

Christoph Hellwig
2010-11-24T14:48:11Z

On Wed, Nov 24, 2010 at 10:10:29AM +0000, James Bottomley wrote:
> The final question is is it worth it? Since USB devices are supposed to
> be hot unpluggable, surely a USB device with a write back cache would be
> a disaster: no-one will SYNC the cache on a surprise unplug anyway ...
> therefore there shouldn't really be any of them surviving in the wild
> (famous last words, I suppose).

There's tons of USB devices with writeback caches. Recent windows
version tend to use the FUA bit a lot because of this. And the linux
usb storage target implementation thus has a hook to ignore the FUA bit,
and it's probably not the only one..