Problems with hosts

Owned by FlexVDI
Apr 15, 2021
2 min read


Q: When registering a flexVDI Host with flexVDI Manager, I get the error  "This Host is already registered with a flexVDI Manager"

A: In order to avoid the accidental registration of a Host with two different Managers,registering a Host that had been previously registered requires the execution of a short manual procedure.

  1. Stop flexVDI Agent

    # service flexvdi-agent stop

  2. Remove the file that stores the registration key.

    # rm /etc/flexvdi/flexvdi-agent-key
  3. Then you can run flexvdi-config and register the Host with the flexVDI Manager.
Q: When starting a new guest, I get the error "Invalid argument" when opening the disk images.

A: flexVDI sets qemu cache mode to "none", which implies the use of the O_DIRECT flag. This requires that the disk operations are aligned with the memory buffers, and qemu works with 512 bytes blocks. So, if you are using volumes with a block size of 4K, I/O calls like pread() will return EINVAL error.

To solve this problem, format disks with a 512 bytes block size. If it were not possible, please contact support to provide a specialized version of flexVDI Agent.

Q: cgroup errors in flexVDI Agent log

A: After rebooting a host, messages like these may appear in flexVDI agent log:

Exception initializing stats for domain XXXXXXX
Requested operation is not valid: cgroup CPUACCT controller is not mounted

The most probable cause is that libvirtd started before cgconfig due to a race condition. To fix this restart libvirtd:

# service libvirtd restart

This does not affect the guests running on the Host.

Q: In a Media Storage I created with flexvdi-config, some files are not visible

A: This usually means the Samba daemon has no read permission for these files. Check that the owner and permission bits are correctly set, and also the SELinux context if you have SELinux enabled (it is on by default). The SELinux tag of files and directories shared by a Samba daemon must be samba_share_t. You can see it with the -Z flag of the ls command. If some of your files do not have this tag, you can quickly fix them with the command:

# restorecon -r /path/to/cifs/share