Virtualization is a cornerstone of modern IT-driven business processes primarily due to its resource optimization capabilities. The data flowing through virtualized environments can be critical for organizations to function properly and support production and services. When the stability and revenue generation of your organization have that severe dependence on data and virtual infrastructure nodes, performing reliable backup and recovery workflows is vital to guarantee data recoverability and business continuity.

KVM (Kernel-based Virtual Machine) is an open-source virtualization solution for Linux environments. The main advantage of Linux KVM is the price – you can download and run this hypervisor for free. Additionally, you can benefit from KVM’s open-source flexibility and adjust the functionalities to the specifics of your infrastructure and tasks.

In this post, we provide recommendations on how to enhance KVM backup and recovery. Consider implementing the tips below into your workflows to secure the data and virtual infrastructure of your organization, minimize downtime, and support production continuity. 

Understanding KVM and Its Backup Needs

KVM is an integrated part of the Linux core and not a separate module. Therefore, the development of KVM goes actively along with that of distributives, especially those of Redhat-based systems. You can choose from various KVM server management systems, such as SolusVM, which is a universal panel. 

Other notable KVM advantages and features include:

• CPU overcommitting support
• Thin provisioning 
• Virtual CPU hot add capabilities 
• Automatic NUMA balancing 
• Advanced privacy
• Resource independence
• Network card emulation, advanced support for protocols, and firewalls

Building and maintaining an efficient KVM environment can be a challenge in and of itself. The hypervisor can take significant time to master the functionality and learn how to perform correct troubleshooting. Additionally, users creating KVM backups can face the following challenges:

• Problems with snapshots not functioning properly
• Backup scheduling and automation via Bash scripts can be complicated
• Non-reliable backup testing and recoverability verification workflows

Considering the difficulties and weak links of KVM hypervisor backup workflows, any organization needs a reliable backup strategy. You can build an efficient backup and recovery system if you implement some key points. 

Best Practices of Linux KVM Backup

To effectively back up a KVM virtual machine or infrastructure, you might want to consider the following: 

Full and incremental backups

A full backup of a KVM virtual machine copies that VM as a whole. You can then send that copy to a repository that is independent of the original machine’s environment. This initial full backup copy is your primary recovery resource that you can use when the virtual machine is down due to disruption. 

However, backups need to be up to date if you want to have smooth recovery capabilities and resume production with minimum data loss. Incremental backups can be your solution here. An incremental backup is a backup that records only the data blocks that have been changed after the last backup.

The key difference between full and incremental backups is in the balance between backup speed and recovery speed:

• Full backups require more time to create and a lot of free storage space, as you need to record large amounts of data in the backup repository. However, a full backup is the fastest solution when you want to recover data with minimum downtime. 
• Incremental backups significantly cut backup windows (i.e. shorten backup workflow duration) because they track and record only the changed data blocks. However, recovery procedures involving incremental backups can take more time because they need to process all the iterations and recordings since the last full backup.

Therefore, when thinking about how to back up KVM virtual machines and environments, consider creating a system involving both full and incremental backups. This tactic enables you to have a relatively fresh backup copy for full and fast recovery in case of a global disaster, and a set of incremental backups to recover separate VMs during minor incidents.

Backups from storage snapshots

In virtualization, snapshots are point-in-time copies of VMs that you can use to roll back a machine to a previously “captured” state. Sometimes, users can treat VM snapshots as backups. That perception of snapshots is not correct and can lead to data loss and compliance issues. 

A snapshot depends on the virtual disk of its VM. Any disruption happening to the hypervisor or hardware running your virtual environment can make snapshots inaccessible. That is why a snapshot on its own is not a backup.  

However, modern data protection solutions can use VM snapshots to create backup copies. They take the “captured” point-in-time state of a VM and replicate that VM as a whole to a different repository. With this approach, you can:

• Ensure backup versioning (you can have multiple snapshots of a single VM in a backup to choose from) to improve your RPO (recovery point objective) and recovery flexibility; 
• Accelerate backup and recovery workflows to achieve tighter RTO (recovery time objective) and reduce the impact of data protection activities on your infrastructure.

Scheduling regular backups

Regularity is key to ensure data relevance in case you need to recover from backup copies. Given the complexity of KVM infrastructures and variety of data circulating throughout IT systems, a KVM backup must have deep automation as a core. Additionally, the pace of data changes and updates makes backup frequency vital to provide fast recoverability. 

In addition to automation, you might want to schedule your backups. Based on the importance of your KVM virtual machines for production, you can set daily, weekly and monthly backups for each of them. Moreover, you can set up modern data protection tools to back up mission-critical virtual machines as often as every minute, ensuring little to no data loss and minimal downtime.

Ensuring backup consistency and integrity

The worst time to discover that your backups are unrecoverable is when a disaster has already happened and your production infrastructure is down. Unfortunately, due to the frequency and typical system load of KVM backup workflows, testing can require too much time and resources. 

You can ensure the consistency and integrity of your KVM backups with the right data protection tools. Modern backup and recovery solutions for KVM and other virtual infrastructures can run application-aware backups, thus ensuring data integrity in spare copies without impacting production. In addition, some solutions enable seamless verification and non-disruptive recoverability testing by schedule and on demand. 

The market offers many data protection solutions for virtualized environments. They have similar capabilities and special features to enhance backup and recovery workflows. Such solutions include: 

• Bacula
• BDRSuite
• NAKIVO
• Storware Backup and Recovery
• Vinchin Backup & Recovery

The key points to consider when picking your solution to back up and restore KVM hypervisor and VM data are:

• Backup and recovery capabilities
• Resource consumption
• RPO and RTO
• Disaster recovery features
• TCO 

You might want to review the functionality and capabilities of every solution and set your own value for each depending on your budget. Some solutions can have or lack specific features such as KVM image backup or granular recovery.

Best Practices for Reliable KVM Recovery

Just like a backup for Hyper-V, VMware and other virtualization solutions, such as Proxmox VE, KVM recovery can be more efficient if you correctly organize workflows. Here are the points to consider when creating and configuring your KVM data recovery sequences:

Testing and verifying backups

The first step is to ensure that you can use your KVM backup data for recovery in emergency cases. To check backup recoverability, you need to test every backup copy you have. 

Consider implementing regular backup testing procedures into your organization’s data protection workflows. You can set your KVM backup solution to verify data recoverability after every backup session. Additionally, consider utilizing non-disruptive testing capabilities to test backups on demand. Such tests do not impact your production infrastructure and network performance.

Recovery planning and staff training 

Prioritize and plan your recovery sequences. For example, you might want to restore critical VMs and the most sensitive records as quickly as possible after an emergency. Because of this, you need to know which workloads and storages you need to recover first. List your resources, map out your infrastructure nodes, define the impact that every machine and storage has on production, and you will have solid grounds on which to build a thorough recovery plan. 

Your IT security specialists and other team members should be aware of these recovery plans and procedures. Additionally, you can consider holding specific training sessions for your employees to ensure that they know their roles and responsibilities in different disaster scenarios. 

Minimizing downtime during recovery

Recovery time objective (RTO) defines the maximum downtime your organization can tolerate without unacceptable consequences. Modern KVM backup solutions can enable near-zero downtime and data loss by utilizing workflow replication functionalities. Whenever your main machine is down, you simply fail over to a synchronized replica and resume operations without disruption. 

However, the main disadvantage of focusing on VM replication is the total price of such systems. Running parallel infrastructures can be too expensive for both SMBs and enterprises. The system cost grows with the number of nodes and the complexity of infrastructures to replicate. 

You can also reduce your RTO by optimizing your hardware and network performance or scheduling full backups to run more frequently. On the other hand, you can rebuild your infrastructure to adjust it to a longer RTO. The more you cut downtime, the more investments and system resources your recovery workflows require. 

Additional KVM Backup and Recovery Tips

In addition to the three best practices above, you might want to implement other recommendations into your KVM backup and recovery system.

Incremental and differential backups

Understanding the differences between incremental and differential backups can help you balance your backup and recovery speed to meet your timing requirements. Unlike incremental backups which record the blocks that have changed since the last backup, differential backups include the changes since the last full backup. A differential KVM backup can help you adjust the balance in workflow durations. 

Differential backup windows can become longer with every new session and occupy more storage space. However, differential backups can be used for faster recovery because they have fewer intermediate changes to process before data restoration. 

Data deduplication and compression

With full, differential, and incremental backups set to provide balanced recovery duration, storage space consumption can significantly increase. To cut costs on physical disks and cloud space subscriptions, you can use data compression and deduplication features built into modern KVM backup solutions.

Data deduplication excludes repeated data blocks (duplicates) to reduce the size of backup copies on the disk. Compression algorithms can re-encode the data to fit more code elements in a single bit. Combined, deduplication, and compression can notably reduce the size of backups. However, compressed and deduplicated backups then take more time to recover. 

Backup encryption

In case you have multiple sites and/or use the cloud to store backups, encrypting data “in flight” is a reliable way to keep it private. For sensitive records, encryption during transfer is mandatory for compliance purposes. 

The other consideration is encryption during the retention period. Hackers searching for data can target backups along with production data. By encrypting KVM backups, you can reduce the probability of data leakage.

Conclusion

Backups are necessary to ensure your organization’s KVM data recoverability and infrastructure resilience. Built-in data protection and recovery capabilities can be insufficient for complex virtual environments and large volumes of data. Consider installing and configuring a specialized KVM backup solution to enable reliable backup automation, scheduling, testing, and storage. You can also benefit from advanced recovery and security capabilities such as backup encryption and KVM disaster recovery in NAKIVO Backup & Replication.

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*** This is a Security Bloggers Network syndicated blog from TuxCare authored by TuxCare Team. Read the original post at: https://tuxcare.com/blog/linux-kvm-backup-and-recovery-expert-tips/