News

9/28/2011
03:50 PM
50%
50%

Get VM Backups Right

Protect disk files and data to keep virtual machines humming.

Virtual machine backups encompass two data sources: the application data inside the VM and the disk files that make up the VM itself. You need to protect both to ensure that you can recover from a failure. This calls for a smart mixture of backup types to satisfy your data protection and recovery objectives as well as some unique considerations and techniques, including snapshots.

Freeze Frame

Backing up a VM while it runs and serves clients is accomplished, regardless of the hypervisor platform, via the creation of a VM snapshot. When a VM is snapshotted, the hypervisor stops writing to its existing disk file and creates a new disk file to write changes to. If the machine is live, it also saves the contents of running memory to a separate file. This allows the backup software to copy the snapshot while letting the VM continue operating. Snapshots are also useful because they serve as VMs copies that can be reused if the original backup effort fails. Snapshots can also be used to restore a VM to a known-good state if updates or changes to the VM cause a glitch.

While snapshots are useful, we can run into problems if we're not careful about management. For example, once an operation is successful, snapshots should be deleted because they gobble storage space. Yet time and again, I've seen administrators use snapshots as quasi-backups instead of how they're intended--as temporary safety nets. If enough snapshots accumulate on a production machine, the VM will run out of space and likely fail. Where there's very little data change, it may be OK to leave some snapshots in production, but be careful.

In addition, disk file backups do not take the place of guest-based backup software agents that run at the VM guest operating system level. These agents provide several advantages over disk file backups. The agents are selective: You have the option to take only the data that's changed or the data you want. Backing up the operating system over and over again doesn't do you any good if all you care about is the application data on the machine.

Best Practices

We recommend backing up the disk files of VMs once per week. Send these backups to a repository, such as a deduplicated SAN, that's also replicated to a secondary site. You can also back up VMs to a repository, such as autoloader, that you can physically move off site. Then, take daily guest-OS-level backups of application files and data. Store the daily backups on a mixture of disk, tape, or replicating storage; good backup products can easily accommodate all three.

A word about deduplication: This process can happen in several places. If your SAN supports deduplication, the dedupe software lives at the controller level and automatically deduplicates data as it passes. You can also use a dedicated deduplication appliance. Finally, some backup agents that sit on the deduplication target can provide source deduplication so that only new data gets backed up. In a disaster recovery scenario, you can simply restore the disk files to a freshly provisioned virtual host cluster and spin up new VMs, bringing you right back to where you were during the disk file backup. Or you can update data on the bare-metal images with a restore from the data-only backup.

Recovery accomplished.

Key Steps To Safeguarding Your VM Disk Files

Our full report on key steps to safeguarding your VM disk files is free with registration.

This report includes 14 pages of action-oriented analysis for IT. What you'll find:
  • How to protect data everywhere
  • How to build in resiliency
Get This And All Our Reports


Comment  | 
Print  | 
More Insights
Comments
Oldest First  |  Newest First  |  Threaded View
More Than Half of Users Reuse Passwords
Curtis Franklin Jr., Senior Editor at Dark Reading,  5/24/2018
Is Threat Intelligence Garbage?
Chris McDaniels, Chief Information Security Officer of Mosaic451,  5/23/2018
Register for Dark Reading Newsletters
White Papers
Video
Cartoon Contest
Write a Caption, Win a Starbucks Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
Current Issue
Flash Poll
[Strategic Security Report] Navigating the Threat Intelligence Maze
[Strategic Security Report] Navigating the Threat Intelligence Maze
Most enterprises are using threat intel services, but many are still figuring out how to use the data they're collecting. In this Dark Reading survey we give you a look at what they're doing today - and where they hope to go.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2018-11505
PUBLISHED: 2018-05-26
The Werewolf Online application 0.8.8 for Android allows attackers to discover the Firebase token by reading logcat output.
CVE-2018-6409
PUBLISHED: 2018-05-26
An issue was discovered in Appnitro MachForm before 4.2.3. The module in charge of serving stored files gets the path from the database. Modifying the name of the file to serve on the corresponding ap_form table leads to a path traversal vulnerability via the download.php q parameter.
CVE-2018-6410
PUBLISHED: 2018-05-26
An issue was discovered in Appnitro MachForm before 4.2.3. There is a download.php SQL injection via the q parameter.
CVE-2018-6411
PUBLISHED: 2018-05-26
An issue was discovered in Appnitro MachForm before 4.2.3. When the form is set to filter a blacklist, it automatically adds dangerous extensions to the filters. If the filter is set to a whitelist, the dangerous extensions can be bypassed through ap_form_elements SQL Injection.
CVE-2018-11500
PUBLISHED: 2018-05-26
An issue was discovered in PublicCMS V4.0.20180210. There is a CSRF vulnerability in "admin/sysUser/save.do?callbackType=closeCurrent&navTabId=sysUser/list" that can add an admin account.