• Installation
  • “Package ’linux-modules-extra-x.x.x-x-generic’ Has No Installation Candidate” Error During Installation on Debian Machines
• Disk
  • “Invalid argument” Error in Disk Status After Adding a Block-Type Disk

Installation

“Package ’linux-modules-extra-x.x.x-x-generic’ Has No Installation Candidate” Error During Installation on Debian Machines

For Debian machines, if you encounter errors similar to the below when installing Linux kernel extra modules, you need to find an available version in the pkg collection websites like this rather than directly relying on uname -r instead:

apt install -y linux-modules-extra-`uname -r`
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Package linux-modules-extra-5.15.0-67-generic is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

E: Package 'linux-modules-extra-5.15.0-67-generic' has no installation candidate

For example, for Ubuntu 22.04, one valid version is linux-modules-extra-5.15.0-76-generic:

apt update -y
apt install -y linux-modules-extra-5.15.0-76-generic

Disk

“Invalid argument” Error in Disk Status After Adding a Block-Type Disk

After adding a block-type disk, the disk status displays error messages:

Disk disk-1(/dev/nvme1n1) on node dereksu-ubuntu-pool1-bf77ed93-2d2p9 is not ready: 
failed to generate disk config: error: rpc error: code = Internal desc = rpc error: code = Internal 
desc = failed to add block device: failed to create AIO bdev: error sending message, id 10441, 
method bdev_aio_create, params {disk-1 /host/dev/nvme1n1 4096}: {"code": -22,"message": "Invalid argument"}

Next, inspect the log message of the instance-manager pod on the same node. If the log reveals the following:

[2023-06-29 08:51:53.762597] bdev_aio.c: 762:create_aio_bdev: *WARNING*: Specified block size 4096 does not match auto-detected block size 512
[2023-06-29 08:51:53.762640] bdev_aio.c: 788:create_aio_bdev: *ERROR*: Disk size 100000000000 is not a multiple of block size 4096

These messages indicate that the size of your disk is not a multiple of the block size 4096 and is not supported by Longhorn system.

To resolve this issue, you can follow the steps

1. Remove the newly added block-type disk from the node.
2. Partition the block-type disk using the fdisk utility and ensure that the partition size is a multiple of the block size 4096.
3. Add the partitioned disk to the Longhorn node.

V2 Data Engine I/O Operations May Get Stuck on Burstable VMs

When using the V2 Data Engine on burstable virtual machines (such as AWS EC2 T-series), I/O operations may time out or become stuck, especially during heavy workloads such as concurrent volume backups or restores.

This issue is typically caused by the node exhausting its allocated CPU credits. The V2 Data Engine relies on the SPDK target daemon (spdk_tgt), which requires a dedicated CPU core and uses intensive polling. When a burstable VM runs out of CPU credits, the cloud provider’s hypervisor severely throttles the CPU. This can cause the V2 data plane to become unresponsive, resulting in I/O timeouts or stuck operations.

Resolution

• AWS EC2: Change the instance credit specification to CpuCredits=unlimited to prevent CPU throttling.
• Other Cloud Providers (GCP, Azure, etc.): Review your burstable VM configuration. Consider upgrading to instance types with dedicated/guaranteed vCPUs, or adjust the bursting configuration to ensure the SPDK process is not throttled.

For more details, refer to Issue #13585.