Are snapshots always consistent?

Farid Hajji me at
Sun May 11 05:55:04 PDT 2003

Hello Jens,

> # I'm somewhat confused about snapshots.
> #
> # Are snapshots (e.g. created with dump -L) supposed to
> # be always in a consistent state?
> #
> # What happens if a snapshot is taken, while background
> # fsck is fixing a filesystem?
> I'm no expert in file systems, but AFAIK the bg fsck mostly looks for
> unreferenced blocks and puts them in the free block bitmap again, while
> dump reads files (contents) and does not store block bitmaps and other
> fs meta information. So, these operations should not interfere with
> one another.

dump saves the contents of inodes. This is more than just file contents and 
fsck operates on inodes. So there is potential for breakage if fsck is in the 
process of modifying inodes (e.g. block counts).

> Regards,
> 	Jens

Farid Hajji -- Unix Systems and Network Management.
Quoth the Raven, "Nevermore." --Edgar Allan Poe.

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