# RDMA, net.core.r/wmem\_max and max-buffers

**URL:** <https://forums.linbit.com/t/rdma-net-core-r-wmem-max-and-max-buffers/1110>\
**Category:** General\
**Tags:** drbd\
**Created:** [December 19, 2025, 9:06am UTC](https://forums.linbit.com/t/rdma-net-core-r-wmem-max-and-max-buffers/1110 "2025-12-19T09:06:37Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![indivar](https://avatars.discourse-cdn.com/v4/letter/i/65b543/32.png) [@indivar](https://forums.linbit.com/u/indivar)\
**Post date:** [December 19, 2025, 9:06am UTC](https://forums.linbit.com/t/rdma-net-core-r-wmem-max-and-max-buffers/1110/1 "2025-12-19T09:06:37Z")

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Hello All,

I am trying out DRBD with RDMA transport.  
The DRBD User guide says that max-buffers must be big enough to hold rcvbuf-size.

How big should these values be for a 200Gbps RoCE/RDMA link?

And is there a relation between rcvbuf-size, max-buffers, and OS settings like net.core.rmem\_max and net.core.wmem\_max?

Thanks,

Regards,

Indivar Nair