On 19-Sep-06, at 9:37 AM, Jim Jackson wrote:
>
>
> On Mon, 18 Sep 2006, Dave Cramer wrote:
>
> > Here's the problem:
> >
> > Customer needs to be able to just plug, and unplug USB drive WITHOUT
> > unmount, or sync.
> >
> > The drive is being used to log data.
> >
> > I was thinking about doing write ahead logging, but then it
> occurs to
> > me that the only issue with disk corruption is when re-arranging the
> > structure of the disk
> >
> > ie doing deletes, creating, removing directories
> >
> > So my idea is to simply create n files named 0001-nnnn where n is
> the
> > size of the flash/size of each file before hand and then simply
> write
> > into those files.
> > My expectation is that the worst thing that will happen is I will
> > lose one file worth of data if it is pulled out before synching the
> > disk.
> > I' will also write 0's to the files before putting the data on them.
> >
>
> I'm not so sure that precreating the files etc will help. You'd really
> need to look at the details of how the particular filesystem you
> are using
> write to and extends files.
My intention is to never extend the file, simply write over what is
there
>
> Check out the "sync" option to mount - should save you some, though it
> hits write performance. Suspect you throughput isn't that great
> that you'd
> worry.
>
Yes, they would be mounted in sync mode
> In general there is no 100% solution to this problem. But maybe the
> data
> being collected doesn't merit the hoops you'd have to go thru' to
> give you
> 100%
>
>
>
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