PXE Magic: Flexible Network Booting with Menus
One of my favorite features of a PXE server is the addition of a Knoppix rescue disk. Now, whenever I need to recover a machine, I don't need to hunt around for a disk, I can just boot the server off the network.
First, get a Knoppix disk. I use a Knoppix 5.1.1 CD for this example, but I've been successful with much older Knoppix CDs. Mount the CD-ROM, and then go to the boot/isolinux directory on the CD. Copy the miniroot.gz and vmlinuz files to your /var/lib/tftpboot directory, except rename them something distinct, such as miniroot-knx5.1.1.gz and vmlinuz-knx5.1.1, respectively. Now, edit your pxelinux.cfg/default file, and add lines like the one I used above in my example:
label 1 kernel vmlinuz-knx5.1.1 append secure nfsdir=10.0.0.1:/mnt/knoppix/5.1.1 nodhcp ↪lang=us ramdisk_size=100000 init=/etc/init 2 ↪apm=power-off nomce vga=normal ↪initrd=miniroot-knx5.1.1.gz quiet BOOT_IMAGE=knoppix
Notice here that I labeled it 1, so if you already have a label with that name, you need to decide which of the two to rename. Also notice that this example references the renamed vmlinuz-knx5.1.1 and miniroot-knx5.1.1.gz files. If you named your files something else, be sure to change the names here as well. Because I am mostly dealing with servers, I added 2 after init=/etc/init on the append line, so it would boot into runlevel 2 (console-only mode). If you want to boot to a full graphical environment, remove 2 from the append line.
The final step might be the largest for you if you don't have an NFS server set up. For Knoppix to boot over the network, you have to have its CD contents shared on an NFS server. NFS server configuration is beyond the scope of this article, but in my example, I set up an NFS share on 10.0.0.1 at /mnt/knoppix/5.1.1. I then mounted my Knoppix CD and copied the full contents to that directory. Alternatively, you could mount a Knoppix CD or ISO directly to that directory. When the Knoppix kernel boots, it will then mount that NFS share and access the rest of the files it needs directly over the network.
Another nice addition to a PXE environment is the memtest86+ program. This program does a thorough scan of a system's RAM and reports any errors. These days, some distributions even install it by default and make it available during the boot process because it is so useful. Compared to Knoppix, it is very simple to add memtest86+ to your PXE server, because it runs from a single bootable file. First, install your distribution's memtest86+ package (most make it available), or otherwise download it from the memtest86+ site. Then, copy the program binary to /var/lib/tftpboot/memtest. Finally, add a new label to your pxelinux.cfg/default file:
label 3 kernel memtest
That's it. When you type 3 at the boot prompt, the memtest86+ program loads over the network and starts the scan.
There are a number of extra features beyond the ones I give here. For instance, a number of DOS boot floppy images, such as Peter Nordahl's NT Password and Registry Editor Boot Disk, can be added to a PXE environment. My own use of the pxelinux menu helps me streamline server kickstarts and makes it simple to kickstart many servers all at the same time. At boot time, I can not only indicate which OS to load, but also more specific options, such as the type of server (Web, database and so forth) to install, what hostname to use, and other very specific tweaks. Besides the benefit of no longer tracking down MAC addresses, you also can create a nice colorful user-friendly boot menu that can be documented, so it's simpler for new administrators to pick up. Finally, I've been able to customize Knoppix disks so that they do very specific things at boot, such as perform load tests or even set up a Webcam server—all from the network.
Syslinux PXE Page: syslinux.zytor.com/pxe.php
Red Hat's Kickstart Guide: www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/sysadmin-guide/ch-kickstart2.html
Kyle Rankin is a Senior Systems Administrator in the San Francisco Bay Area and the author of a number of books, including Knoppix Hacks and Ubuntu Hacks for O'Reilly Media. He is currently the president of the North Bay Linux Users' Group.
Kyle Rankin is a VP of engineering operations at Final, Inc., the author of a number of books including DevOps Troubleshooting and The Official Ubuntu Server Book, and is a columnist for Linux Journal. Follow him @kylerankin.
Practical Task Scheduling Deployment
July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
Join Linux Journal's Mike Diehl and Pat Cameron of Help Systems.
Free to Linux Journal readers.Register Now!
- Stunnel Security for Oracle
- SourceClear Open
- Murat Yener and Onur Dundar's Expert Android Studio (Wrox)
- SUSE LLC's SUSE Manager
- My +1 Sword of Productivity
- Managing Linux Using Puppet
- Google's SwiftShader Released
- Non-Linux FOSS: Caffeine!
- Parsing an RSS News Feed with a Bash Script
- SuperTuxKart 0.9.2 Released
With all the industry talk about the benefits of Linux on Power and all the performance advantages offered by its open architecture, you may be considering a move in that direction. If you are thinking about analytics, big data and cloud computing, you would be right to evaluate Power. The idea of using commodity x86 hardware and replacing it every three years is an outdated cost model. It doesn’t consider the total cost of ownership, and it doesn’t consider the advantage of real processing power, high-availability and multithreading like a demon.
This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide