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    SubjectRe: Dump corrupts ext2?
    Andreas Dilger writes:
    > On Oct 10, 2001 19:11 -0400, Doug McNaught wrote:
    > > Lew Wolfgang <wolfgang@sweet-haven.com> writes:
    > > > I was looking for some scripts to backup ext2 partitions
    > > > to multiple CDR's when I stumbled onto "cdbackup" at
    > > > http://www.cableone.net/ccondit/cdbackup/.
    > > >
    > > > Alas, there is a warning saying:
    > > >
    > > > "WARNING! When using this program under Linux, be sure not to use
    > > > dump with kernels in the 2.4.x series. Using dump on an ext2
    > > > filesystem has a very high potential for causing filesystem
    > > > corruption. As of kernel version 2.4.5, this has not been
    > > > resolved, and it may not be for some time."
    > >
    > > I'm pretty sure this is because dump reads the block device directly
    > > (which is cached in the buffer cache), while the file data for cached
    > > files lives in the page cache, and the two caches are no longer
    > > coherent (as of 2.4).
    >
    > In Linus kernels 2.4.11+ the block devices and filesystems all use
    > the page cache, so no more coherency issues.

    Um, I thought that there wasn't going to be coherency? For example, if
    you open /dev/sda and /dev/sda1, they each have a separate cache. I
    remember some debate about this, and Linus pointed out how hard it was
    to make things coherent.

    Regards,

    Richard....
    Permanent: rgooch@atnf.csiro.au
    Current: rgooch@ras.ucalgary.ca
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