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    SubjectRe: Ext2 defragmentation
    Date
    On Wed, 17 Nov 1999 13:14:45 -0500, you wrote:

    >
    > No, it's not a problem because the backup superblock doesn't need to be
    > written to during the course of normal operations. (The critical
    > parameters which e2fsck needs to do its thing don't change after the
    > filesystem is created; they do change after a resize2fs, though, so some
    > care is needed in that case.) So it's just a matter of
    >

    I see. I guess I was thinking of the case where the fs was suffciently damaged
    so that one would have to kickstart e2fsck with a backup superblock location.
    Maybe this never works inpractice so it's not worth the trouble.


    > I've noticed another anomaly. When mke2fs 1.18 creates a 1.3GB partition, it
    > says the first backup superblock is at 32768 not 32769. Is this an
    > off-by-one error?
    >
    > No; for 2k and 4k filesystems, the primary superblock is located at
    > offset 1024 of block #0. (Where the first 1k of block #0 is reserved
    > for the boot loader). On 1k filesystems, primary superblock is located
    > at block #1, and so the block group boundaries are shifted down by 1
    > block.
    >
    > - Ted

    Ah, I get it. Thanks for the info.



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