Re: Any protection against 'bit rot' ?

[Colin Percival <cperciva@tarsnap.com>]

On 11/23/10 02:35, Andy wrote:
> Sorry if this is answered on a FAQ, or has been raised on the list
> before.  Tarsnap's moto is "Online backups for the truly paranoid", so
> today I've got my paranoid hat on.  I am building a home NAS and am
> trying to keep its data as safe as possible from silent corruption aka
> 'bit rot' - it has ECC RAM, and data will live on ZFS.  I would like
> to have the same warm feeling about the data that I send for off-site
> backup.  What protection does tarsnap have against this kind of data
> loss?

As other people have commented, Tarsnap uses cryptographic signatures to ensure
that archives haven't been mangled (either deliberately or accidentally).  There
is no ECC built into Tarsnap, but all the Tarsnap data is stored on S3, which
has extensive replication and checksumming; so 'bit rot' is less of an issue for
Tarsnap than it would be for a local ZFS disk.

-- 
Colin Percival
Security Officer, FreeBSD | freebsd.org | The power to serve
Founder / author, Tarsnap | tarsnap.com | Online backups for the truly paranoid