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    SubjectRe: ext4: total breakdown on USB hdd, 3.0 kernel
    On Sun 2014-06-29 17:04:28, Theodore Ts'o wrote:
    > On Sun, Jun 29, 2014 at 10:25:16PM +0200, Pavel Machek wrote:
    > >
    > > One more thing that I noticed: fsck notices bad checksum on inode, and
    > > then offers to fix the checksum with 'y' being the default. If there's
    > > trash in the inode, that will just induce more errors. (Including
    > > potentially doubly-linked blocks?) Would it make more sense to clear
    > > the inodes with bad checksums?
    >
    > Metadata checksums aren't in e2fsprogs 1.41 or 1.42. It will be in
    > the to-be-released e2fsprogs 1.43, and yes, we need to change things
    > so that the default answer is to zero the inode. We didn't do that
    > initially because we were more suspicious of the new metadata checksum
    > code in the kernel and e2fsprogs than we were of hardware faults.
    > :-)

    :-). Aha, and I misremembered, it was block descriptor checksums, not
    inode checksums:

    One or more block group descriptor checksums are invalid. Fix? yes

    Group descriptor 0 checksum is invalid. FIXED.
    Group descriptor 1 checksum is invalid. FIXED.
    Group descriptor 2 checksum is invalid. FIXED.
    Group descriptor 3 checksum is invalid. FIXED.

    I'm still trying to figure out what went wrong in the OLPC-1.75 + USB
    disk case.

    One possibility is that OLPC is unable to provide enough power from
    the two USB ports to power Seagate Momentus 5400.6, and that the hard
    drive fails to detect the brown-out and does something wrong. (Are
    SATA drives expected to work at 4.5V? Because that's what is
    guaranteed on USB, IIRC).

    Heavy corruption happened when I was charging the phone _and_ running
    the hard drive, from the OLPC. Now I have seen cases when OLPC crashed
    on device plug-in, in what looked like a brown-out...

    Best regards,
    Pavel

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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