Archive
Posts from 2009
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 →Website re-design gotchas, and how to avoid them!
I recently re-designed my main website, and learned quite a bit about CSS and XHTML in the process. I also learned that there are a number of things you should do before re-designing a site, and thought I would list them here for folks who are looking to change their site layout: Validate your documents with a free validator See how your site loads in various browsers Sketch out how you want thing to look before you start coding Make sure to design with the future in mind (this especially applies to associating CSS classes with tags) Make sure you consult best practices Read a good CSS reference before you begin Make sure you integrate USEFUL ads into your website (this will help cover hosting costs, which aren't free) Ask an expert what they like and dislike about your site Verify that your site doesn't have broken links Implement things iteratively (there is no need to do everything at once) Keeping these things in mind will made re-designing your site quite a bit easier, and may even turn up some surprises that you weren't aware of.
$ read more →Using kdump to get core files on Fedora and CentOS hosts
One of things I love about Solaris is its ability to generate a core file when a system panics. The core files are an invaluable resource for figuring out what caused a host to panic, and are often the first thing OS vendor support organizations will request when you open a support case. Linux provides the kdump, diskdump and netdump tools to collect core file when a systems panics, and although not quite as seamless as their Solaris counterpart, they work relatively well. I'm not a huge fan of diskdump and netdump, since they have special pre-requisites (i.e., operational networking, supported storage controller, etc.) that need to be met to ensure a core file is captured…
$ read more →Creating sparse files on Linux hosts with dd
Sparse files have become pretty common in the virtualization arena, since they allow you to present a large chunks of disk space to guests without having to reserve the space in an actual backing store. This has a couple of benefits: Most guests use a fraction of the disk space allocated to them, so sparsely allocating files cuts down on the amount of disk space required to host them Additional storage can be added over time to support growth (disk storage keeps getting cheaper, so this can actually lead to a reduction in operational costs) Backing up the guests requires less tape / disk space (this assumes your backup solution supports sparse files) To create a sparse file on a Linux host, you can run dd with a count size of zero (this tells dd not to write any data to the file), and then use the seek option to extend the file to the desired size: Once the sparse fie is created, you can use dd to verify how much space is allocated to it: Sparse files are extremely handy, though it's important to know when and when not to use them.
$ read more →Zoning Brocade switches Putting it all together
I wanted to conclude my Brocade zoning posts by discussing a couple of best practices. Two issues I have seen in the real world are inconsistent and non-descriptive names, and a lack of configuration backups. Using descriptive names such as "Fabric1Switch1Port8" or "AppServer1Port1" makes the output quite a bit more readable, which is extremely helpful when you are trying to gauge the impact of a faulty initiator or SFP at 3am. Backing up the configuration on a switch is super easy to do, and there are a number of tools available to automate this process (I have written pexpect scripts to do this)…
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