[DRBD-user] drbd-8.3.9rc2.tar.gz

J. Ryan Earl oss at jryanearl.us
Wed Oct 20 23:27:23 CEST 2010


On Wed, Oct 20, 2010 at 6:57 AM, <rf at q-leap.de> wrote:

> I don't see why you want to distinguish between "user-space" and
> "kernel-space" SDP.


User-space sockets and kernel-space sockets use different code paths and
thus can behave differently.


> I assume by the former you mean using libsdp
> together with the kernel module ib_sdp. While this method uses a syscall
> interface to ib_sdp rather than direct "in-kernel operations" like drbd,
> both methods actually use the basic code in ib_sdp.
>

While the ib_sdp module is necessary for both cases, the code paths are
still not identical.  User-space SDP is by far the most common usage case,
other than DRBD I know of no other kernel-space SDP consumer.  The
user-space SDP path is much, much better tested than the kernel-space SDP
path.  I highly doubt there is any regression testing done for the in-kernel
SDP path between releases as it is such a fringe usage case.


>
> But anyway, this discussion doesn't lead to a solution of the
> problem.


It does actually, if you understand the problem: the problem being your SDP
implementation not DRBD.


> In my understanding, SDP support is an advertised feature of
> DRBD, and I bought Infiniband hardware just because of that. All I want
> now is some assistance in debugging this. I believe there are a number
> of other users who would be happy if DRBD over SDP were working.  If SDP
> support is not a supported feature anymore, it should be clearly stated
> though.


You need a kernel with a working SDP implementation, the kernel you've
chosen has a broken implementation.  I've gotten SDP working with DRBD, is
does work, when the Kernel has a non-broken SDP socket implementation.
 You're blaming the wrong piece of software for your problem if you blame
DRBD.

What problem do you have with using IPoIB?  Your choices are: Use IPoIB or
use a different Kernel with a working kernel-space SDP implementation.  You
should probably contact your IB vendor for OFED support if you're dead set
on using SDP instead of IPoIB.

-JR
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