high-tech sorcery - technology indistinguishable from magic

Possible HTPC System

specialj — Sat, 27 Jun 2009 13:10:56 -0700

ASRock ION 330 ($400)
Hauppauge WinTV-HVR-950Q ($70)
nMEDIAPC HTPCKB-B Keyboard + Remote Combo ($80)

Total: $550

Trying a new firewall for Windows

specialj — Tue, 09 Jun 2009 16:32:39 -0700

I’ve recently been asked to recommend a Windows firewall and I really had no answer. I use Windows so rarely and within a protected virtual environment that a firewall is not really necessary. Still, since I support Windows machines from time to time it helps to have a go-to solution for anti-virus, anti-malware, and firewall. I decided to take a look at what was out there. I looked at what was being recommended and given high ratings. Then I eliminated choices due to bloat (such as ZoneAlarm 8 which is a 50MB+ download). The remaining candidates were:

Looking a routers for dual wan configuration

specialj — Fri, 05 Jun 2009 17:10:22 -0700

I wanted to stay under $250 and cam across theseL

Cisco Small Business RV042 - $153, no session tracking?, power and heat issues?
SYSWAN SW24 VPN - $190, rack mountable, 2 year warranty, upnp
Cisco Small Business RV082 - $250, same problems as RV042?, don’t need extra ports

The SYSWAN SW24 VPN looks like a winner.

RSRuby, Rails, and R documentation and articles

specialj — Tue, 02 Jun 2009 21:06:40 -0700

RSRuby

R

some reading from today

specialj — Tue, 02 Jun 2009 00:25:34 -0700

notebookreview.com has a first look at the Dell Studio 14z, an announcement about the MSI X-Slim X340, and a review of Quicken Deluxe 2009.
techreport.com has a review of the new 6-core AMD Opterons (Istanbul core)
I noticed that the Duty Calls xkcd comic is the first when searching google for “someone is wrong on the internet” (with or without quotes).
distantocean.com has a theory about why libertarianism appeals to nerds

Howto install the rsruby gem on Ubuntu 9/04

specialj — Wed, 27 May 2009 17:54:04 -0700

This took a few minutes of figuring out and I suspect these same steps might be common across Debian and Ubuntu variants and versions.

sudo aptitude install r-base-core
sudo gem install rsruby -- --with-R-dir=/usr/lib/R --with-R-include=/usr/share/R/include

Looking for an inexpensive switch which can perform port failover

specialj — Sat, 02 May 2009 13:16:59 -0700

While many networking setups would be better off with link aggregation and failover I have a networking configuration where I just need the failover. Specifically I have a GNU/Linux server that is performing traffic shaping for a bunch of other systems but I want to make sure that the server is not a single point of failure. I believe this can be accomplished with a switch that supports RSTP and where one links can be set to various costs. The best model I've found so far is the Netgear GS108T 8 port gigabit smart switch. I haven't purchased it yet but it looks like it would suite my needs and costs around $100.

Rails gems and plugins I use to accomplish specific tasks

specialj — Fri, 01 May 2009 13:25:25 -0700

I’ve been doing a bit of Rails development and I’ve been finding some new gems and plugins that I’ve really liked. I’m happy that a lot of developers are switching from plugins to gems which gives better version control then pulling from the development branch of the source code. I haven’t listed everything, just those that I feel comfortable recommending, which means those I’ve used in multiple projects and for some time with success. There are definitely some entries I can imagine replacing if I spent the time looking for something better.

Playing with Mozilla Songbird

specialj — Fri, 01 May 2009 12:51:23 -0700

I’ve been playing with Songbird today and I’ve bene liking it. I found my user experience was much improved after installing the add-ons FireTray and More Native (I also tried NativeBird and was not pleased). Now all I need is global hot keys and this could become my default music player. Perhaps support for Lala.com might be nice too.

Xen and KVM versions for various Debian and Ubuntu versions

specialj — Fri, 17 Apr 2009 04:44:47 -0700

I’ve had a had time keeping track of which versions of which virtualization systems are in each Debian and Ubuntu OS. This is important for picking your host OS. So I’ve made up a table with the various versions.

Exciting changes in the 2.6.30 Linux kernel

specialj — Thu, 16 Apr 2009 03:42:18 -0700

Every Linux kernel release has interesting changes but 2.6.30 really stands out to me as having a lot of features I would like to take advantage. In 2.6.29 the only really great feature to me was the inclusion of barrier support for simple DM devices. It’s only 1 change but an important one in my opinion as it will allow an increase in either performance or reliability for LVM and dm-crypt devices. But 2.6.30 has a lot of changes that I am likely to take advantage of such as:

Using virtio drivers under KVM

specialj — Sat, 11 Apr 2009 16:44:20 -0700

As I’ve been doing a lot more work with KVM I’ve come to prefer it over Xen from a management perspective. However, the performance sometimes not what I would like it to be. The KVM developers are working to improve performance through the creation of paravirtualized drivers. These drivers are included in Linux so I began testing them. Unfortunately I did not read the LibVirt VirtIO wiki page which recommends using Linux 2.6.25 or later. I can verify that the virtio-net driver in Ubuntu 8.04 which uses 2.6.24 is prone to crashing under load. And the virtio-disk driver has geometry problems. So, the lesson is to use a more recent kernel such as those in Debian 5.0 (Lenny) or Ubuntu 8.10 (Intrepid Ibex).

Low power server platforms

specialj — Tue, 07 Apr 2009 16:56:08 -0700

I was doing some research on various energy efficient platforms for a server project. I decided to take notes on the 3 energy efficient server platforms that are currently available. To qualify the CPU had to have 4 cores and consume 60 watts or less. The motherboard had to use DDR2 or DDR3 and not FB-DIMM’s. I noted the approximate prices for comparison purposes.

Which SSD drive to buy

specialj — Tue, 07 Apr 2009 14:56:14 -0700

AnandTech had a nice series of articles about SSD’s recently:

I think the results can be summed up, for the purpose of purchasing, as follows:

Intel X25-E - highest cost, highest performance
Intel X25-M - high cost, high performance
OCZ Vertex - medium cost, medium performance
- This drive is based on an Indilinx controller and other drives based on the same controller should be comparable such as the SuperTalent UltraDrive ME or the G.Skill Falcon
everything else - low performance, not worth buying

Preventing a service from starting on Debian or Ubuntu

specialj — Tue, 07 Apr 2009 14:18:22 -0700

I have been tending to run MySQL on my computers for the purpose of Rails app development. However, for my laptop especially, I prefer if MySQL is not started by default. I prefer to start it manually if it’s needed. When I first started looking into changing the behavior I came across update-rc.d, as I suspect many people do. The man page makes it clear that update-rc.d is only intended for package installation and removal scripts. While there are programs such as sysv-rc-conf and bum I find those to be overkill if one only has to change one item. My solution is fairly simple.

Keeping time on KVM guests

specialj — Tue, 24 Mar 2009 01:32:27 -0700

I've been doing more work with KVM as of late. Though once a huge proponent of Xen I am finding myself increasingly rolling out KVM solutions. While it's a subject for larger article I am feeling that Linux as a hypervisor makes management easier for a number of tasks. However, one thing I've noticed is that with KVM the guest clocks are not kept in sync with the host. This is somewhat wasteful since the host inevitably uses NTP to keep its clock correct. Apparently in later guest linux kernels one can use the kvmclock clocksource which keeps the guests time synchronized to the host. But when is not using a newer kernel, or another operating system altogether, I cannot find any documentation on best practices. It seems clear that the tsc clocksource is problematic if used in either the host or the guest and there are also stories of problems with hpet on the host and mixed stories with using jiffies. I've had acpi_pm used in both the host and the guest and experienced time skewing. I'm not sure that changing the host clocksource would help, and I'm not sure I want a requirement of a certain clocksource for all guests. I suppose the guests could always simply run NTP. At least until all my guest systems run a newer Linux kernel. That seems like a suboptimal solution though.

Rails: Marshal vs YAML vs JSON for data serialization

specialj — Mon, 09 Mar 2009 01:15:30 -0700

I noticed a performance issue in an app that was using the ActiveRecord serialize method. It turns out that using the YAML library has known performance problems. Alternatives to using YAML are using JSON or using Marshal. Marshal is by far the fastest but it’s a binary format that may change over time which could lead to compatibility errors. JSON is much faster than YAML but slower than Marshal. I’ve also noticed that JSON does not seem to handle the nil case correctly. It’s hard to make a recommendation but I think JSON is probably the best way to go as long as the speed is acceptable and you’re willing to test for nil. It also may be a pretty easy to hack a fix for the nil case. For more speed at the possible expense of compatibility than Marshal would seem a better choice.

Testing out a new keyboard

specialj — Tue, 10 Feb 2009 19:47:45 -0800

I have been wanting a smaller keyboard for my desk for some time so I finally went ahead and ordered a BTC-6100C, largely due to more favorable ratings and reviews when compared with the Adesso MCK-91 which had also caught my eye. I am fairly happy with it as it is quieter and more responsive than the keyboard it replaced, and of course much smaller. The only issues I've had in adjusting are hitting the right shift key, the left alt key, and delete. But I'm getting there and would definitely count the keyboard as a step up. It's not for everyone but for people looking for a smaller keyboard it might be worth a look.

A slew of gem updates recently

specialj — Wed, 04 Feb 2009 20:17:10 -0800

I’ve noticed a lot of gems that I use have been updated recently. Here are some of the highlights:

authlogic 1.4.0 - I’ve been very excited about authlogic since finding it. I may even try to put it in an application tonight. I was never a fan of restful_authentication or acts_as_authenticated. Code generation can be useful for teaching but not for taking advantage of an improving codebase.
icalendar 1.1.0 - I was looking to switch an app to vpim_icalendar due to bugs I’ve found in icalendar. Now I’m interested to try the new version of icalendar and see if it clears up the problems I’ve been experiencing.
rdiscount 1.3.1.1 - I still haven’t settled on a markdown gem yet but rdiscount is still in the running.
httparty 0.3.0 - I haven’t used this one yet though I’ve considered it for interfacing with twitter. Its advantages compared to twitter specific gems (twitter, twitter4r) is that it is far more flexible and can be used to talk with other restful web services.
net-ssh, net-sftp, net-scp, net-ssh-gateway - This whole suite has gotten an update. So far my only use for the gems is capistrano.

Also (Update)

capistrano 2.5.4
thoughtbot-factory_girl 1.1.5

DDoS DNS attacks

specialj — Tue, 03 Feb 2009 01:01:58 -0800

Like many people I’ve seen the query (cache) './NS/IN' denied in my logs. It seems like most sysadmins, including myself, reacted by blocking traffic to the ip addresses in the logs at the firewall level. When these attacks first began there was very little information but I decided to take an extended look at the problem tonight. Using a firewall makes the most sense when you’re blocking the attackers but in this case the ip addresses were not the attackers but, rather, the victims.