TrilioVault for RHV does provide the capabilties to take application consistent backups by utilizing the Qemu-Guest-Agent.
The Qemu-Guest-Agent is a component of the qemu hypervisor, which is used by RHV. RHV automatically builds all VMs to be prepared to use the Qemu-Guest-Agent.
The Qemu-Guest-Agent provides many capabilities, including the possibility to freeze and thaw Virtual Machines Filesystems.
The Qemu-Guest-Agent is not developed or maintained by Trilio. Trilio does leverage standard capabilities of the Qemu-Guest-Agent to send freeze and thaw commands to the protected VMS during a backup process.
Installing the Qemu-Guest-Agent
The Qemu-Guest-Agent needs to be installed inside the VM.
The Qemu-Guest-Agent requires a special SCSI interface in the VM definition.
This interface is automatically created by RHV upon spinning up the Virtual Machine.
The installation process depends on the Guest Operating System.
The Qemu-Guest-Agent is calling the fsfreeze-hook.sh script either with the freeze or the thaw argument depending on the current operation.
The fsfreeze-hook.sh script is a normal shell script.
It is typically used to do all necessary steps to get an application into a consistent state for the freeze or to undo all freeze operations upon the thaw.
Location of the fsfreeze-hook.sh script
The fs-freeze-hook.sh script default path is:
Content of the fsfreeze-hook.sh script
The fsfreeze-hook.sh script does not require a special content.
It is recommended to provide a case identifier for the freeze and thaw argument.
This can be achieved for example by the following bash code:
case "$1" in
#Commands for freeze
#Commands for thaw
echo quot;Neither freeze nor thaw provided"
Example fsfreeze-hook.sh for MYSQL
This example flushes the MySQL tables to the disks and keeps a read lock to prevent further write access until the thaw has been done.