[OpenAFS] Overview? Linux filesystem choices

[Stephan Wiesand]

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On Oct 1, 2010, at 16:20, Douglas E. Engert wrote:

> On 10/1/2010 4:35 AM, Harald Barth wrote:
>>=20
>> Another way to tackle the data corruption issue in the AFS case would
>> be to add checksum functionality to the fileserver backend. In
>> contrast to NFS, we have the advantage that noone reads the data
>> directly from the file system but always through the client.
>=20
> ZFS stores the checksum of a block, not in the block, but in a higher =
level
> block. This can then detect if a block failed to be written when its =
read back.
> Other file systems could not detect this, as they would read old data,
> with an old checksum.

We've also seen disks randomly reading and returning a different sector =
than the one requested.

> Keep this in mind if checksums are added to AFS.

This would be an awesome feature to have. Presumably, for each file one =
would keep an auxiliary one with, say,  4 or 8 bytes of checksum for =
each 512 bytes block of payload? Or 64 bytes of Hamming codes, allowing =
single bit error correction and dual bit detection?

--=20
Stephan Wiesand
DESY -DV-
Platanenallee 6
15738 Zeuthen, Germany





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