# Performance Regression in DRBD RDMA Between 9.3.0 and 9.3.1

**URL:** <https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176>\
**Category:** DRBD\
**Tags:** drbd\
**Created:** [March 12, 2026, 10:28am UTC](https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176 "2026-03-12T10:28:19Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![abegorov](https://avatars.discourse-cdn.com/v4/letter/a/eb9ed0/32.png) [@abegorov](https://forums.linbit.com/u/abegorov)\
**Post date:** [March 12, 2026, 10:28am UTC](https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176/1 "2026-03-12T10:28:19Z")

</div>

The new DRBD release (9.3.1) exhibits a severe performance degradation for RDMA. Transfer rates plummet to a handful of MB/s, far below expectations for a 100 Gb/s Infiniband connection equipped with a single Mellanox ConnectX-5 card.

For example, copying 11400 MB starting out at 1.3 GB/s rapidly deteriorates afterward. The final 100 MB segments complete at just 2.5 MB/s and 1.1 MB/s:

```shell
# dd if=/dev/zero of=test bs=1M count=11400 status=progress oflag=direct
10686038016 bytes (11 GB, 10 GiB) copied, 8 s, 1.3 GB/s
# dd if=/dev/zero of=test bs=1M count=100 status=progress oflag=direct
104857600 bytes (105 MB, 100 MiB) copied, 43 s, 2.5 MB/s
# dd if=/dev/zero of=test bs=1M count=100 status=progress oflag=direct
104857600 bytes (105 MB, 100 MiB) copied, 94.2242 s, 1.1 MB/s

```

---

<div class="post-metadata">

**Author:** ![abegorov](https://avatars.discourse-cdn.com/v4/letter/a/eb9ed0/32.png) [@abegorov](https://forums.linbit.com/u/abegorov)\
**Post date:** [March 12, 2026, 1:21pm UTC](https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176/2 "2026-03-12T13:21:30Z")

</div>

There is no such problem in 9.2.17.

---

<div class="post-metadata">

**Author:** ![michael](https://yyz1.discourse-cdn.com/flex003/user_avatar/forums.linbit.com/michael/32/16_2.png) [@michael](https://forums.linbit.com/u/michael)\
**Post date:** [March 13, 2026, 3:01pm UTC](https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176/3 "2026-03-13T15:01:25Z")

</div>

Thanks for reporting. I’ve passed this on to the DRBD development team.

---

<div class="post-metadata">

**Author:** ![phil\_reisner](https://avatars.discourse-cdn.com/v4/letter/p/779978/32.png) [@phil\_reisner](https://forums.linbit.com/u/phil_reisner)\
**Post date:** [April 16, 2026, 12:55pm UTC](https://forums.linbit.com/t/performance-regression-in-drbd-rdma-between-9-3-0-and-9-3-1/1176/4 "2026-04-16T12:55:13Z")

</div>

We fixed that now. The fix will be released with 9.3.2