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Article on Installing, Configuring And Debugging The ISC DHCP Server
I just posted an article on how to install, configure and debug the ISC DHCP server. The example configuration referenced in the article supports Windows, OS X, Linux and Solaris hosts, and provides the directives needed to PXE boot physical and virtual machines (I have tested it with Xen, KVM, Linux and Solaris). If you have any comments or suggestions, please let me know.
$ read more →Getting To Know the Linux Kernel Virtualization Machine (KVM)
I gave a talk last night on theLinux Kernel Virtual Machine (KVM) at the local Linux users group. The talk gives some background on KVM, and shows how to get KVM working on a server that supports processor virtualization extensions. The slides are available on my website, and I will try to get them linked to the presentation section of the ALE website. Thanks to everyone who came out…
$ read more →Boot tracing in the Linux 2.6.28 kernel
While perusing the Linux change list, I noticed that boot tracing was introduced in the 2.6.28 kernel: "The purpose of this tracer is to helps developers to optimize boot times: it records the timings of the initcalls. Its aim is to be parsed by the scripts/bootgraph.pl tool to produce graphics about boot inefficiencies, giving a visual representation of the delays during initcalls. Users need to enable CONFIG_BOOT_TRACER, boot with the "initcall_debug" and "printk.time=1" parameters, and run "dmesg | perl scripts/bootgraph.pl > output.svg" to generate the final data." This is pretty sweet, and I will definitely have to test this out once I finish up Redhat cluster suite + GFS testing!
$ read more →Brendan Gregg screaming at a 7410!
Slashdot picked up a youtube video of Brendan Gregg, shouting at a Sun 7410. Its pretty halarious, but it does showcase just how cool the DTrace Analytics visual GUI is on Sun's new line of Amber Road products. Brendan is one of the co-authors of Solaris Internals, 2nd Edition. He also wrote the DTraceToolKit, which has allowed millions of SysAdmins who don't have the skills to deep dive into DTrace to harness its powa!
$ read more →Snooping loopback interfaces on Solaris hosts
One thing that I have always enjoyed about Linux is the ability to snoop traffic on loopback interfaces. This is extremely useful for debugging local communication problems, and the fact that you couldn't until recently do this on Solaris hosts was extremely annoying(especially in the world of zones!). I just read Peter Memishian's blog entry on the IP observability code that was recently putback into opensolaris, and low and behold you can now snoop loopback interfaces on Solaris hosts. This is awesome, and the ability to snoop by zone id is by far my favorite feature: The Solaris network stack just keeps getting better and better, and with the upcoming crossbow and IPMPng putbacks just around the corner, networking in Solaris will only get better…
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