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    SubjectRe: [RFC][PATCH 0/2]Extend ext3 filesystem limit from 8TB to 16TB
    On Thu, 2006-03-30 at 10:40 -0700, Andreas Dilger wrote:
    > On Mar 29, 2006 17:38 -0800, Mingming Cao wrote:
    > > Have verified these two patches on a 64 bit machine with 10TB ext3
    > > filesystem, fsx runs fine for a few hours. Also testes on 32 bit machine
    > > with <8TB ext3.
    > Have you done tests _near_ 8TB with a 32-bit machine, even without these
    > patches?
    No I haven't. The >8TB right now is attached to a 64 bit machine, but we
    should able to move it to a 32 bit machine.

    > In particular, filling up the filesystem to be close to full
    > so that we really depend on the > 2TB code to work properly?

    I made a kernel patch to allow a file to specify which block group it
    wants it's blocks to allocate from(using ioctl to set the goal
    allocation block group). I set the goal block group falls to somewhere
    >8TB, and did dd tests on that file. Verified this with debugfs, the
    allocated block numbers are beyond 2**31.

    Also before run fsx tests, created many directories (32768 at most:) and
    verified one directory's inode is located in block group >8TB space. So
    when we do fsx test on files under that directory, we are
    creating/testing files >8TB.

    BTW, do you think this ioctl is useful in general for other users? I
    attached the patch here.

    I also plan to hack the code of inode allocation to force all files's
    inode is put in the block group >8TB, so that we could do a full
    filesystem tests there.

    > Also, in
    > theory with these patches even a 32-bit machine could run > 8TB, right?
    > There have been sporadic reports of failure for large ext3 filesystems,
    > and some of them say that 32-bit systems fail and 64-bit systems work.
    > There is a kernel bugzilla bug open for this, but it was never really
    > identified what the source of the problem was.

    Sure, I will verify that on my 32 bit machine with >8TB.

    > Cheers, Andreas
    > --
    > Andreas Dilger
    > Principal Software Engineer
    > Cluster File Systems, Inc.



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