# drbd-9.2.21-rc.1 and drbd-9.3.5-rc.1 **URL:** \ **Category:** Release Announcements\ **Tags:** kubernetes, drbd\ **Created:** [November 3, 2026, 6:41pm UTC](https://forums.linbit.com/t/drbd-9-2-21-rc-1-and-drbd-9-3-5-rc-1/1299 "2026-11-03T18:41:25Z")\ **Posts on this page:** 1\ **Page:** 1
**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:** [November 3, 2026, 6:41pm UTC](https://forums.linbit.com/t/drbd-9-2-21-rc-1-and-drbd-9-3-5-rc-1/1299/1 "2026-11-03T18:41:25Z")
Hi, The DRBD-9.3.5-rc.1 release brings two new features. First, it adds an interface to use one of DRBD’s change-tracking bitmaps to support backup software. Together with the new drbd-utils release, it adds new commands to enable, reset, and dump tracked changes in an extent-list format. This is compatible with what many backup software programs can consume to optimize taking incremental backups. To get this to backup software, LINSTOR will also support it, and our integrations with Kubernetes, OpenStack, OpenNebula, and Apache CloudStack (and others if possible) will support passing the CBT information as well. The second new feature worth mentioning is a reworked RDMA transport. It is called rdma2, and it builds on recent work (released with drbd-9.3.1) allocating receive buffers in large chunks. Under optimal conditions, that means with large BIOs, I saw lab machines maxing out a 100Gbps link using Connext-X5 cards while replicating a write stream with DRBD. Another change is completely transparent for you as users. We are switching the netlink family to drbd2. This is an important step for bringing drbd-9 to upstream Linux. It will allow us to have a drbd-9 in upstream Linux that is compatible with very old drbd-8.4 drbd-utils. On top of that, the release includes a large number of bug fixes. We fixed many bugs identified by the community and by us at LINBIT, as we use more and more LLMs to analyze events in DRBD clusters. This is a release candidate. Please test it. 9.3.5-rc.1 (api:genl2/proto:86-101,118-125/transport:23) -------- \* Track changed blocks for incremental backups: a tracking bitmap slot    records every write to the backing device; cbt-flush and cbt-start    bracket a snapshot taken while I/O is suspended on all nodes \* suspend-io now also waits for the barrier ack of the last epoch, so    that with protocols A and B the writes are on the peers' stable    storage too; flush-to-peers=no skips that wait \* Add rdma2, a new RDMA transport that moves all data with one-sided    RDMA-WRITE, sends bios zero-copy, and fails over to a surviving path    when a link goes down \* Serve the new drbd2 netlink family next to the drbd family \* Optionally serve DRBD 8.4 userland over the netlink family at version    1 (CONFIG\_DRBD\_NL\_DRBD1, rpmbuild --with nl\_drbd1,    DEB\_BUILD\_OPTIONS=nl\_drbd1); off by default \* Fix lb-tcp skipping a path for good after the peer closed it first    during a disconnect, which starved every later handshake \* Fix spurious and racy "bitmap locked" warnings when bitmap operations    on different peer slots run concurrently \* All fixes from 9.2.21-rc.1   - Fix a resync target staying Inconsistent with nothing left to sync:     when the Primary cannot reach the sync source, after aborting a weak     sync source, and when P\_RS\_CANCEL\_AHEAD overtakes the Ahead state     change   - Fix a reconciliation resync target waiting in WFBitMapT forever, and     out-of-sync bits from before a lost diskless Primary being dropped at     equal dagtags   - Fix a peer's connect-time upgrade from Outdated going unnoticed,     which left writes unreplicated   - Fix an Outdated sync source being marked UpToDate after a resync     with failed blocks   - Fix the day0 slots, a regression in 9.2.20: forget-peer left a slot     that the next UUID bump filled with a later generation, and a peer     created from the day0 UUID could be refused as unrelated data;     attach repairs such meta data   - Fix promoting a peer that holds an older generation of the data a     diskless Primary exposes   - Fix P\_OUT\_OF\_SYNC: never sent for Primaries with node-id 8 or higher,     a crash after del-peer of a Primary, and writes left pending for a     peer that lost its connection   - Fix the activity log: AL updates turned off while a crashed Primary     resyncs, the superblock written too late on "al-updates no", and the     in-core AL not written when AL updates come back on   - Fix a dry-run connect (--tentative) establishing the connection     without a resync   - Fix the last close returning before the peers have the last write on     stable storage, and auto-demote failing on a pending signal   - Fix call-pri-lost-after-sb killing the receiver instead of demoting   - Fix online resize: drain application I/O before the commit and before     a participant replies, cache the peers' size answers per volume, and     refuse a too small peer while syncing from a larger one   - Fix a receiver deadlock at the end of a resync when the link fails     while the bitmap is written, and bound the memory a bitmap write-out     holds   - Fix resync pacing: the fixed resync-rate (c-plan-ahead 0) holds, the     resync queue at the backing device is bounded so application I/O does     not wait behind it, and DRBD logs when max-buffers or c-max-rate     limit a resync   - Fix connect and disconnect issues: a spurious NetworkFailure right     after a handshake, a stale ping timeout dropping the next connect, a     peer's close while connecting taken as a network error, ko-count 0     being counted down, and a second peer accepted beside a DRBD 8.4 peer   - Fix lb-tcp: a NULL pointer dereference in the receiver, a CPU spin     when the peer closes mid-payload, zero-length data chunks, hot-adding     paths, and listeners left on unused paths   - Fix rdma: use-after-free and refcount underflows on teardown during     connect, a 60 s hang after a failed establish, going StandAlone on an     interrupted connect, and a crash with a peer running rdma2   - Fix the TLS handshake compat code (upstream fixes): leaks, refcount     and use-after-free bugs, and a missing admin check on DONE   - Fix memory corruption by peer\_device flags on 32-bit kernels   - Fix a negative ap-in-flight after a resend, BarrierAck count warnings,     sending on after a send failed, and an unsent packet flushed at     disconnect ("Wrong magic value" on the peer)   - Fix attach hanging after the node was a verify target, and a double     release when linking the holder fails   - Show the submit and sent ages of requests in debugfs again, and mark     peer writes that completed locally   - Fix building SUSE KMPs on SLES 16, and the build with     CONFIG\_DRBD\_TIMING\_STATS [https://pkg.linbit.com/downloads/drbd/9/drbd-9.3.5-rc.1.tar.gz](https://pkg.linbit.com/downloads/drbd/9/drbd-9.3.5-rc.1.tar.gz) > > > Signed-off-by: Philipp Reisner \ [https://pkg.linbit.com/downloads/drbd/9/drbd-9.2.21-rc.1.tar.gz](https://pkg.linbit.com/downloads/drbd/9/drbd-9.2.21-rc.1.tar.gz) > > > Signed-off-by: Philipp Reisner \ cheers, Philipp