Re: Amanda VFAT Incremental Backups Broken in linux-2.2.1[12]

Robert de Bath (rd103983@home-box.demon.co.uk)
Sat, 4 Sep 1999 07:39:10 +0100 (BST)


On Fri, 3 Sep 1999, Riley Williams wrote:

> Hi Robert.
>
> > DONT BACKUP VFAT INCREMENTALLY
>
> > There is only one date on a file on a VFAT partition and as
> > every command down to the DOS copy command preserves that date
> > you cannot see what's been changed.
>
> > Hopefully the ctime is being set to now (or now-1); this is the
> > _right_ thing to do.
>
> > There is a good feature of VFAT (I _DONT_ believe it !!! a GOOD
> > feature in VFAT!!!!!!!) in the archive bit. This would provide
> > reliable incrememtal backups ... but it can't be mapped onto
> > Unix semantics.
>
> Depends what you mean by 'mapped' actually. My suggestion would be to
> use it to determine the mtime to be presented, according to the
> following rules:
>
> 1. If the archive bit is set, anything asking for the mtime
> gets one of the following:
>
> a. The current time.
>
> b. The latest of the system boot time and the ctime time.
>
> Which is chosen would depend on the exact semantics required.
>
> 2. If the archive bit is clear, anything asking for the mtime
> always gets the ctime time.
>
> Perhaps somebody can advise what is wrong with that?
>
> The only possible problem I can see is in the fact that there would
> have to be some means to turn the archive flag off that worked with
> the various backup programs and was consistant with the semantics
> used.
A?

Have you got confused about ctime vs mtime ?

But yes you could do:
mtime = dos_mtime
ctime = arch?now:dos_mtime
atime = dos_mtime

But how do you reset the Arch bit ?

-- 
Rob.                          (Robert de Bath <http://poboxes.com/rdebath>)
                    <rdebath @ poboxes.com> <http://www.cix.co.uk/~mayday>

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