# \[Rocky 8.5\] Root Cause Inquiry: Server Hang and Continuous "Affinity broken due to vector space exhaustion"
**URL:** https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682
**Category:** Rocky Linux Help & Support
**Tags:** rocky-linux-8, dell
**Created:** [July 19, 2026, 12:42pm UTC](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682 "2026-07-19T12:42:15Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@Oks](https://forums.rockylinux.org/u/Oks)
#### Post date: [July 19, 2026, 12:42pm UTC](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682/1 "2026-07-19T12:42:16Z")
Hello everyone,
I am currently investigating a critical server hang incident on a single standalone server running Rocky Linux 8.5.
This server operates as a dedicated logging service that receives mirrored traffic over a 10GbE network from 6 production database servers, filtering and logging DB-related packets in real time.
Recently, the system suddenly became completely unresponsive (Hang state) and required a hard reset. Notably, we were continuously monitoring the server’s resource utilization, and at the time of the hang, both CPU and memory usage were extremely stable at around 20%.
Upon analyzing the system logs, the only suspicious error found was the following message, which is still continuously flooding my logs every single minute even after the reboot.
> **Affinity broken due to vector space exhaustion**
Through **my** initial investigation, **I** confirmed that this correlates with Red Hat Bugzilla **BZ#2084646** and Rocky Linux Errata **RLSA-2022:6460**.
While **I** now know which bug it is and that a kernel upgrade is required, **I am** struggling to find clear technical references that explain the exact **causal relationship (correlation) between this specific error log and a complete system hang**.
If anyone has experienced this exact issue or can share insights into the technical chain of events that leads from vector exhaustion to a total system freeze, **I** would be incredibly grateful. Specifically, **I** would highly appreciate your expertise on the following 4 points.
#### **Environment:**
- **OS:** Rocky Linux 8.5
- **Kernel Version:** `4.18.0-348.el8.0.2.x86_64`
- **irqbalance Version:** `1.9.2-1.el8.x86_64`
- Hardware Specs :
```auto
Server Model: Dell PowerEdge R550
CPU: Intel Xeon Silver 4309Y (8C/16T)
RAM: 128GB (DDR4-2666 16GB RDIMM x 8)
Storage: 2.4TB 10K RPM SAS 12Gbps (Hot-plug)
Network Card: Intel X710 Dual Port 10GbE SFP+ Adapter (PCIe)
```
#### **1. Detailed Mechanism of Vector Space Exhaustion**
Could someone explain the exact technical root cause of how the `irqbalance` utility and the kernel’s APIC vector management system interact to trigger this? Since the `Affinity broken` logs were continuously printed over a long period before the hang, does this bug cause a “gradual leak” of interrupt vectors over time during routine IRQ balancing? How does the limit of ~202 user-space vectors per CPU actually get depleted?
#### **2. Correlation between Continuous Logs and the Sudden Server Hang**
How does this gradual vector exhaustion eventually culminate in a complete, sudden server freeze? Does the system finally reach a breaking point where critical storage (SAS/NVMe) or network driver interrupts go completely unserviced, resulting in fatal I/O blockage, driver timeouts, or kernel deadlocks?
#### **3. Log & Diagnostic Validation**
Based on a scenario where these error messages continuously repeat and eventually end with an abrupt system hang, is it safe to definitively conclude that the hang is a direct consequence of the bug described in BZ#2084646?
#### **4. Immediate Temporary Workarounds**
Apart from upgrading the kernel (which requires a strict scheduled maintenance window), what are the best temporary workarounds to stabilize the system in its current state? (e.g., Disabling the `irqbalance` daemon entirely, specific configuration tweaks, or banning certain high-traffic IRQs from being balanced?)
Any detailed technical insights, design docs, or architectural explanations would be immensely helpful for our report.
Thank you in advance for your time and expertise!
---
### Author:  [@gerry666uk](https://forums.rockylinux.org/u/gerry666uk)
#### Post date: [July 19, 2026, 5:24pm UTC](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682/2 "2026-07-19T17:24:57Z")
> [@Oks](#):
>
> Affinity broken due to vector space exhaustion
You could try (as root)
`systemctl stop irqbalance.service`
or disable it.
But the hang might not be related.
---
### Author:  [@iwalker](https://forums.rockylinux.org/u/iwalker)
#### Post date: [July 20, 2026, 10:45am UTC](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682/3 "2026-07-20T10:45:13Z")
In addition to what @gerry666uk said, and what I found by googling the error you posted:
> [@](#):
>
> The message _“Affinity broken due to vector space exhaustion”_ **indicates that your Linux kernel has run out of available interrupt vectors (specifically the 202 assignable vectors per CPU) to bind a hardware device’s IRQ to a specific CPU core**. [[1](https://access.redhat.com/solutions/5609981), [2](https://git.zx2c4.com/wireguard-linux/commit/?h=jd/unified-crypt-queue&id=743dac494d61d991967ebcfab92e4f80dc7583b3), [3](https://www.cnblogs.com/10087622blog/p/15703497.html)]
>
> This typically happens during SR-IOV Virtual Function (VF) pass-through to virtual machines, or when a system has an extremely high number of hardware interrupts. When this limit is reached, the kernel silently assigns the interrupt to an unconstrained CPU outside your requested affinity mask. [[1](https://www.reddit.com/r/VFIO/comments/frcr3f/affinity_broken_vector_space_exhaustion/), [2](https://access.redhat.com/solutions/5609981), [3](https://git.zx2c4.com/wireguard-linux/commit/?h=jd/unified-crypt-queue&id=743dac494d61d991967ebcfab92e4f80dc7583b3)]
>
> **How to Diagnose and Fix**
>
> **1. Adjust `irqbalance`**
> In many cases, the system’s IRQ balancer struggles to properly map interrupts across multiple NUMA nodes, leading to localized vector exhaustion. You can restart or disable it: [[1](https://support.scc.suse.com/s/kb/Affinity-broken-due-to-vector-space-exhaustion-log-messages-observed-in-dmesg)]
>
> - **Stop and disable the service:** Run `systemctl stop irqbalance.service && systemctl disable irqbalance.service`.
> - **Update your OS:** Ensure your distribution’s `irqbalance` package is up to date, as newer versions have improved NUMA node mapping. [[1](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682), [2](https://support.scc.suse.com/s/kb/Affinity-broken-due-to-vector-space-exhaustion-log-messages-observed-in-dmesg?language=fr), [3](https://support.scc.suse.com/s/kb/Affinity-broken-due-to-vector-space-exhaustion-log-messages-observed-in-dmesg)]
>
> **2. Stop Irqbalance and Use Custom Affinity Masks**
> If the issue persists, you may need to disable dynamic balancing entirely and statically bind your interrupts away from congested CPUs (often CPU 0): [[1](https://www.cnblogs.com/10087622blog/p/15703497.html), [2](https://git.zx2c4.com/wireguard-linux/commit/?h=jd/unified-crypt-queue&id=743dac494d61d991967ebcfab92e4f80dc7583b3)]
>
> - Use the **[Red Hat Customer Portal](https://access.redhat.com/solutions/5609981)** to view advanced scripts for adjusting `/proc/irq/*/smp_affinity` and managing hardware interrupt distributions. [[1](https://access.redhat.com/solutions/5609981), [2](https://www.cnblogs.com/10087622blog/p/15703497.html)]
>
> **3. Mask or Pin PCIe/VF Interrupts**
> For VF pass-through environments (like KVM or VMware), the issue frequently occurs because too many Virtual Functions are trying to assign vectors to a single NUMA node’s CPU pool: [[1](https://support.scc.suse.com/s/kb/Affinity-broken-due-to-vector-space-exhaustion-log-messages-observed-in-dmesg), [2](https://www.reddit.com/r/VFIO/comments/frcr3f/affinity_broken_vector_space_exhaustion/), [3](https://www.cnblogs.com/10087622blog/p/15703497.html), [4](https://support.scc.suse.com/s/kb/Affinity-broken-due-to-vector-space-exhaustion-log-messages-observed-in-dmesg?language=fr)]
>
> - On AMD Threadripper or NUMA-heavy systems, review your UEFI/BIOS settings and ensure that IOMMU groups and PCIe root ports aren’t overly saturating the localized CPU cores. [[1](https://www.reddit.com/r/AskUbuntu/comments/fbx8rm/kernel_spams_affinity_broken_due_to_vector_space/), [2](https://www.reddit.com/r/VFIO/comments/frcr3f/affinity_broken_vector_space_exhaustion/), [3](https://www.cnblogs.com/10087622blog/p/15703497.html)]
but in reality, the real way to fix it is by upgrading. Rocky 8.5 is no longer supported, only Rocky 8.10 is supported. Other than the kernel fixes, updates will also fix a load of other CVE and security issues, so running an outdated system like this is a risk. It would be best to update this as soon as possible.
---
### Author:  [@system](https://forums.rockylinux.org/u/system)
#### Post date: [September 18, 2026, 10:45am UTC](https://forums.rockylinux.org/t/rocky-8-5-root-cause-inquiry-server-hang-and-continuous-affinity-broken-due-to-vector-space-exhaustion/20682/4 "2026-09-18T10:45:56Z")
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