If you're a SysAdmin, or work anywhere on the Ops side of DevOps, a rescue disc should be an essential part of your arsenal. With a bootable rescue system, either on a CD or on a thumb drive, you can recover a password, detect and remove a rootkit or other malware, repair a Master Boot Record, retrieve data from a damaged drive and more.
You can build your own, of course. All of the necessary tools are freely available under open source licenses and are included in the repositories of most Linux distributions. But the easier route is to use one of the Linux distributions designed specifically as a rescue disc, and which comes with all of the tools you might need already installed. There are many, but we'll look at three of the most popular. Each includes tools to fix problems on machines running either Linux or Windows.
Although SystemRescueCD has a reputation for being a little difficult to learn, it's loaded with tools useful for a network administrator. It supports network file systems like samba and nfs, as well as ntfs, ext2/ext3/ext4, reiserfs, btrfs, xfs, jfs and vfat. Included are tools for backing up data, cloning drives, disc buring, and for managing or repairing partitions. Also included: file editors and replacement bootloaders, as well as network troubleshooting and diagnostic tools. Of course there is antivirus, as well as other anti-malware detection and removal tools.
Trinity Rescue Kit comes with many of the same capabilities as SystemRescueCD, although without support for as many file systems. However, this rescue system has one feature that might prompt you to keep a just-in-case copy on hand. At startup, it offers the option to boot into various modes, which might be useful with a machine that doesn't want to boot even from a USB drive or CD.
While it's a good idea to keep several different rescue disks on hand -- the right tool for the job and all that -- if I were limited to only one, The Ultimate Boot CD might well be the one I'd pick. Why? Because this one includes a couple of features to help you determine if you're dealing with a hardware or software problem. In addition to tools for working with file systems, partitions, maleware and the like, this one comes with tools for testing memory, CPU and disks, as well as BIOS management tools that could be handy to have on hand.
If you're looking for a rescue disk to add to your toolbox, I'd recommend downloading all of these. Play around with each and get used to their use and capabilities. I'd keep a bootable copy of each around, since they all contain some unique features. One of these will likely become your go-to tool -- until you run across another in your travels that you like better.