Joe
On 14-Sep-06, at 7:25 PM, Joe Bouchard wrote:
> On Thu, Sep 14, 2006 at 03:04:02PM -0400, Dave Cramer wrote:
> > I have a requirement for a system that the USB drive will be pulled
> > without warning. Is there such a thing ?
> >
> > Dave
>
> I've thought about this myself, but haven't made a decision. My
> issue is that
> the power may go out without notice. A couple of thoughts....
>
> - I don't think there is a bombproof solution, just risk reduction.
Well in my case I have specific information that I am writing to the
disc and I can control the computer that reads it
So, I think using Write Ahead Logging I can get pretty close to bomb
proof since I won't be deleting anything
>
> - I don't want to start a flame war, but I suspect ext3 is as good
> as any from a
> reliability standpoint. Others may be better on high performance
> tasks, but
> high performance and USB drive don't belong in the same sentence
> anyway.
> http://linuxgazette.net/102/piszcz.html
I am not concerned with performance. This is a flash drive after all!
There are others that show promise
xfs, or wasabi ?
>
> - If you can, write programs to mount -> write -> sync -> umount,
> hence possibly
> 99% of the time you are unmounted which eliminates issues. Or if
> you need
> read access all the time and write access occasionally, remount -o
> rw, write,
> remount -o ro, etc. Or at least sync after writing.
well, you can mount the filesystem in sync mode which circumvents the
kernel's buffering
>
> - Can you hook up a push button connected to a Digital input? Have
> a program
> monitoring it, and when the button gets pushed, you sync, umount,
> turn on
> LED. Then you tell the customer "push button, wait until the light
> comes on,
> pull drive". This reduces the "without notice" part.
ran that by marketing, got shot down.
>
> - I expect some drives may be better than others. Faster is
> probably better
> because it will sync quicker and should be less out of date. Using
> the combo
> SD/USB devices with the SD bus on the embedded computer, and the USB
> connection on the office computer may work better... not sure.
>
> Hope that helps. Good luck.
> Joe
>
>
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