[lustre-discuss] max_frags 257 too large

Moreno Lazaro Diego (ID) diego.moreno at id.ethz.ch
Thu Sep 8 04:07:55 PDT 2022


Hi Einar,

I've seen this in older versions of Lustre-2.12 where map_on_demand=1 on the ko2iblnd module is needed in order to keep compatibility with newer versions. There are a couple of patches where this requirement for map_on_demand was removed though it's now set by default:

https://jira.whamcloud.com/browse/LU-15094 (don't require map_on_demand to negotiate max_frags)
https://jira.whamcloud.com/browse/LU-15186 (set by default map_on_demand)

I know at least DDN includes these patches on their 2.12.6-ddn8 version. I don't see the patches on the latest 2.12.9 on the community version. Maybe you just need to enable map_on_demand and that could solve it.

Regards,

Diego

On 08.09.22, 11:22, "lustre-discuss on behalf of Einar Næss Jensen" <lustre-discuss-bounces at lists.lustre.org on behalf of einar.nass.jensen at ntnu.no> wrote:

    We have a case of one of our MDS servers stopped working correctly (we have failed over the mdt to other mds server), and while we wait for vendor response, I see something in our logs which I'm curious about:

    LNet: 117894:0:(o2iblnd_cb.c:2631:kiblnd_passive_connect()) Can't accept conn from 10.145.30.168 at o2ib (version 12): max_frags 257 too large (256 wanted)

    What does it mean? is it somethinbg to be concerned over?



    Best Regards
    Einar Næss Jensen
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