[Gluster-devel] Bitrot/Tering : Bad files get migrated and hence corruption goes undetected.

[Joseph Fernandes]

Well correctly we dont migrate the existing signature, the file starts it life fresh in the new tier(i.e get the bit rot version 1 on the new tier),
Now this is also the case with any special xattr/attributes of the file.
Again we rely heavily on the dht rebalance mechanism for migrations, which also doesnt carry special attributes/xattr.


----- Original Message -----
From: "Niels de Vos" <ndevos at redhat.com>
To: "Joseph Fernandes" <josferna at redhat.com>
Cc: "Gluster Devel" <gluster-devel at gluster.org>
Sent: Friday, February 26, 2016 10:33:11 PM
Subject: Re: [Gluster-devel] Bitrot/Tering : Bad files get migrated and hence corruption goes undetected.

On Fri, Feb 26, 2016 at 09:32:46AM -0500, Joseph Fernandes wrote:
> Hi All,
> 
> This is a discussion mail on the following issue, 
> 
> 1. Object is corrupted before it could be signed: In this case, the corrupted
>    object is signed and get migrated upon I/O. There's no way to identify corruption
>    for this set of objects.
> 
> 2. Object is signed (but not scrubbed) and corruption happens thereafter:
>    In this case, as of now, integrity checking is not done on the fly
>    and the object would get migrated (and signed again in the hot tier).
> 
> 
> The (1) is definitely not a issue with bitrot with tiering. But (2) we can do something to avoid
> corrupted file from getting migrated. Before we migrate files we can scrub it, but its just a naive
> thought, any better suggestions? 

Is there a reason the existing signature can not be migrated? Why does
it become invalid?

Niels