Disaster recovery framework

Migration Aid

Relax-and-Recover also helps administrators with the process of moving a system to a different environment – whether physical or virtualized hardware. Transferring a hardware-based server to a virtual machine (P2V) is quite simple, but, as always, the devil is in the details – of the virtualization software, in this case. As a first experiment, the test team converted an application server (Ubuntu 12.04 LTS) with a MySQL database from an old Dell PC with a faulty RAID drive to a virtual machine on a XenServer [5].

Creating the rescue system and the backup did not differ from the steps discussed previously. To boot the image, we created an ISO storage repository (NFS ISO storage) in the XenServer configuration. As the VM template, we chose Other; the other templates refused to cooperate.

During the recovery process, Relax-and-Recover asked a few questions about the network card (Figure 4) and the hard disk, because of, first, the modified virtual hardware and, second, the different drive size. We had to explicitly confirm the device file change from /dev/sda to /dev/xvda and had no problems downsizing the disk.

Figure 4: The physical NIC eth0 is no longer available. You select virtual hardware provided by XenServer and listed here.

When migrating an old laptop (Debian 8) P2V, the test team had to trick both VMware [6] and VirtualBox  [7]. The rescue system again landed on a USB stick. To boot from this medium, USB 2.0 support had to be activated on the virtual machine. Moreover, we used a special boot manager named Plop [8], because VMware and VirtualBox cannot boot natively from USB. The subsequent rear recover command then proceeded without any glitches.

Pure Relaxation

Relax-and-Recover showed hardly a weakness during our tests. Only cloning a laptop with a solid-state disk and the subsequent migration to an older computer with an EIDE drive failed. Even customizing the scripts did not help in this case; a bug report has been submitted. The program is constantly learning new tricks, which makes us optimistic. For example, the upcoming version 1.18 includes support for NVM Express, an interface to connect SSDs via PCI Express, for the first time.

In all of our other experiments, the disaster recovery tool was convincing. With a few simple commands, you can generate rescue systems and then provide them on CD, USB media, or via a PXE boot image. Relax-and-Recover also proves extremely cooperative when it comes to backups. Not only does it have its own minimal backup routines, it works with known and flexible backup software from other vendors.

The Author

Oliver Hoffmann works as a system administrator at Digital Online Media (DOM). Thanks to Relax-and-Recover, he not only has full mastery over his own laptop, he can rely on this software for customer systems.

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