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Re: Too much time wasted installing fedora on raid1

On Tue, 2005-12-20 at 11:19 +0100, Arjan van de Ven wrote:
> but.. it might as well be marked clean. there's no information in
> never-used parts of the disk after all... so why sync it instead of
> pretending it's synced perfectly fine....

Because it's RAID, and it doesn't know anything about the file system --
it's just trying naïvely to keep the _block_ device synchronised,
without any of that helpful knowledge about which blocks the file system
actually cares about, or might have touched since the array was last
known to be consistent.

This is one of the reasons I believe RAID is the wrong solution; a
better option would be to have the file system natively handle
redundancy across block devices, rather than having two separate layers
each of which know nothing about the other.

Imagine a 'RAID resync' which only needed to resync those blocks which
the file system's journal says have been modified since the state was
last consistent...


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