The New and Improved techslaves.org…

Well, here it is. The new and improved techslaves.org. Well, I don’t actually know if it’s improved but sure is new. In a rash decision, I’ve decided to drop any fantasy of supporting a community of tech-minded people through techslaves.org. The site was previous an SMF forum with a nice mod called TinyPortal that I used to publish articles and coax friends and acquaintances into submitting their own content for publishing.

Community building is hard and I’m lazy. What more can I say?

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Books24x7: Not Impressed

That’s right, you read it correctly: I’m not impressed with Books24x7.

It’s not their collection (plenty of stuff for various fields of interest) and it’s not their price (I’m using it under a campus subscription so what’s to complain about?). It’s their interface.

Could it be anymore annoying to read a book than the Books24x7 experience? Was this website designed in the 90s?

What frustrates me the most is that you cannot usefully navigate/read a book on Books24x7 without the use of a mouse. Sure, I can use Spacebar, the arrow keys or Page Up/Page Down to navigate on a single page, but because each “page” is just a small chunk of text, you need to constantly be clicking the “Next” link. Tab key link navigation, you say? There are so many links at the top of the page that tabbing through all of them to reach the “Next” link takes longer than grabbing for the mouse.

This is just a terrible book reading experience. Perhaps I’ve just been spoiled by… I dunno? PDF files and Preview.app or Stanza? I want to read some of these books but Books24x7 just makes it so unpleasant that I’d rather just find the hardcopies at the library or pay for a decent ebook version that I can read on whatever device or with whatever software that might actually be designed with some thought regarding the reading experience.

Cfengine 3 Snippets Part 1: DenyHosts

I’ve recently begun looking into configuration management with cfengine 3. I’ve ignored this growing sub-field of system administration for too long and I just can’t ignore it anymore. After spending quite some time researching the philosophies, methods and different tools out there, I settled on starting out with cfengine 3. There’s no special reason that I chose cfengine instead of puppet, bcfg2, chef or AutomateIT. I haven’t used any of these tools and thus I cannot pass judgement on them or their methods. All these projects seem to have intelligent and highly motivated people behind them. I simply gravitated towards cfengine because of its strong academic background and the fact that version 3 now represents the most recent and modern research in the field by Mark Burgess et. al.

As part of my learning experience with cfengine, I’ve decided to start posting some of the code that I’ve begun developing in the hopes that by writing about it, I can learn better, faster and maybe even receive some helpful comments from readers along the way. Beware, I’m a cfengine newbie and so what I post here should NOT be copy and pasted into your environment unless you’re ok with the potential of wildly breaking things!

The first snippet of code I want to discuss is related to managing our DenyHosts configuration. As part of our “security policy”, I would like to ensure that every RedHat/CentOS system is running a properly configured DenyHosts instance. Here is what I’ve come up with so far.

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RHEL/CentOS, NFS and Firewalls

I recently decided that it’s about time to setup consistent, explicit and tight firewall policy across our Linux (mostly RHEL/CentOS) servers. One of the initial issues I faced was NFS. NFS implementations are very well known to make use of the portmapper and dynamically assigned port for rpc.mountd and because of this dynamic assignment, firewalling NFS can be challenging.

Luckily, RedHat’s /etc/sysconfig/nfs configuration file read by  various “nfs”, “nfslock” and RPC services init scripts provides an easy means of locking down specific ports for all the NFS-related services so that one doesn’t have to work around the dynamic port assignment problem when it comes to firewalling.

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Atempo Time Navigator 4.2 Archive Media Selection Tunable

Just a quick post here to share a non-obvious tunable for Atempo’s Time Navigator 4.2 regarding archiving and media selection.

Before upgrading from 4.1 to 4.2 Time Navigator’s media selection for archive jobs with standalone drives behaved as expected: If existing partly filled and open cartridges in the associated media pool existed, Time Navigator would request those media be placed in the drives upon the start a new archive operation, effectively only asking for new, unlabeled media to be inserted once the existing media was full.

However, with the upgrade to 4.2 we found that Time Navigator was no longer requesting the existing, partly filled, open cartridges and was instead requesting new, unlabeled media to be inserted into the drives instead! The result of this new behavior was that Time Navigator would use new tapes for every new archive operation, no matter if existing, partly filled and open media was available in the media pool. Basically 4.2′s default behavior was preventing us from filling any archive media unless the particular archive job would happen to be larger than a single tape.

While I don’t know why the functionality changed, I do know what tunable to modify in order to make 4.2 behave like 4.1. The tunable is “check_external_cart_when_recycling“. Setting this tunable to “Yes” has restored the 4.1 behavior, allowing us to make full use of all archive media capacity by only requesting new media when all the existing media in the media pool has been filled.

I believe we only faced this problem because we use standalone archive tape drives that do not have an autoloader or robot nor an “inventory” of online tape. Each tape must be manually loaded. I suspect that if we had an autoloader for our tape drives, that 4.2 would have made the correct/expected selection of media.

I doubt that anyone else is going to face this problem but it took about 3 weeks with Atempo’s R&D department to figure out the problem so I figure if posting here can save anyone that amount of time, then I’ll have done my part!

iPod Touch Woes – Part Deux

The problems with my iPod Touch haven’t gone away just yet.

I was able to replace the headphone jack without too much trouble, in fact I would say it was a pretty easy fix. The old ribbon cable stub left from the snapping of the old ribbon cable came off the PCB without too much trouble at all. Just applied a bit of heat and up she came. Soldering the new ribbon cable+headphone jack assembly was very straight forward as well. I just made sure to clean the four pads off nicely, add a tiny bit of solder to each pad then put the ribbon cable down on top and apply some heat. From there I added a bit more solder to the top because the ribbon cable pads have little holes in them to allow the solder to flow through from the back to the front. All said and done, I think I did a really good job.

But, and here’s the kicker, I think ruined ANOTHER battery! Arg! These things must be ultra sensitive to shorting out or otherwise because I can’t figure out what else might have caused my THIRD battery to die on me. Yes, I’ve accidentally shorted it momentarily while fixing the headphone jack AGAIN.

Alas, perhaps it was not meant to be. First battery died because I tore the casing by accident, second battery because I got the damn thing wet. And now the third battery because I appearently cannot keep the red and black leads apart at all times…

At this point I’m not sure what to do. Give another battery a short? These things are cheap, so why not?