e2image doesn't get backup superblocks?
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I've noticed that e2image doesn't get the backup superblocks and group descriptors. Is this intentional or an oversight? Is there a way to resync the backups from the master copy? e2fsck doesn't seem to do it.
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Quoted 3 lines · Phillip Susi
I've noticed that e2image doesn't get the backup superblocks and group descriptors. Is this intentional or an oversight?
It's deliberate. I suppose it might be useful if you are using e2image -r to make a copy of a corrupted file system, where the primary superblocks are corrupted. It's probably reasonable to save a copy of the first backup superblock just so that e2fsck run on the raw image mimicks what you'd see if you were running on the same file
system. I'd accept a patch to do this.
Quoted 2 lines
Is there a way to resync the backups from the master copy? e2fsck doesn't seem to do it.
Why do you want to do this? In general the tools will automatically sync the backups from the master if it is necessary (i.e., in the case of a file system resize, or if there is a change in the file system features). Otherwise, we deliberately try to avoid modifying the backups, since any updates to the backups is an opportunity to copy corrupted values to the backups, or otherwise risk write failures that could smash the backups.
But if you really do want to copy the master superblock and block descriptor blocks ot backups, you can do it via the following:
debugfs -w /dev/sdb1
debugfs: dirty
debugfs: close -a
debugfs: quit
Regards,
- Ted
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Quoted 7 lines · Ted Ts'o
Why do you want to do this? In general the tools will automatically sync the backups from the master if it is necessary (i.e., in the case of a file system resize, or if there is a change in the file system features). Otherwise, we deliberately try to avoid modifying the backups, since any updates to the backups is an opportunity to copy corrupted values to the backups, or otherwise risk write failures that could smash the backups.
Because I was experimenting with e2fsck -E discard on a raw image and it was clobbering the superblock, and the backups weren't in the image.
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