Re: Erasure coded pools and 'feature set mismatch' issue

[Gregory Farnum <gfarnum@xxxxxxxxxx>]

With that release it shouldn't be the EC pool causing trouble; it's the CRUSH tunables also mentioned in that thread. Instructions should be available in the docs for using older tunable that are compatible with kernel 3.13.

-Greg

On Saturday, November 7, 2015, Bogdan SOLGA <bogdan.solga@xxxxxxxxx> wrote:

Hello, everyone!

I have recently created a Ceph cluster (v 0.94.5) on Ubuntu 14.04.3 and I have created an erasure coded pool, which has a caching pool in front of it.

When trying to map RBD images, regardless if they are created in the rbd or in the erasure coded pool, the operation fails with 'rbd: map failed: (5) Input/output error'. Searching the internet for a solution... I came across this page, which seems to detail exactly the same issue - a 'misunderstanding' between erasure coded pools and the 3.13 kernel (used by Ubuntu).

Can you please advise on a fix for that issue? As we would prefer to use erasure coded pools, the only solutions which came into my mind were:

• upgrade to the Infernalis Ceph release, although I'm not sure the issue is fixed in that version;

• upgrade the kernel (on all the OSDs and Ceph clients) to the 3.14+ kernel;

Any better / easier solution is highly appreciated.

Regards,

Bogdan

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