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Computers, Science, Technology, Xen Virtualization, Hosting, Photography, The Internet, Geekdom And More

Reliable, Available Or Highly Available?

Published on Sept. 29, 2007 at midnight by XC

I’ll probably get a bunch of hate mail over this one, but that’s nothing new Many people seem to be confused when I use the word reliable when talking about a cluster of computers, they seem to be used to the word available. In particular, they seem used to the phrase highly available. Aren’t clusters confusing enough without jargon and buzzwords?

All three words do adequately describe a few different kinds of cluster configurations. Lets go through them.

Available – This means, a computer is on-line running some kind of service that permits some kind of interaction from remote users (usually, via the Internet). Not much interesting there. Some engineers use the word available to indicate that something is not reliable. This simply means, whatever service that is running (or group of services) is prone to breaking under stress.
Highly Available – As described above, whatever it is that you hope to run breaks easily under stress. A highly available cluster of computers will balance incoming requests across a small ‘farm’ of computers that run services that are considered to be available. If one, two or sometimes even several of these computers fail, users are still able to access the remaining computers. Highly available clusters often use shared storage and some kind of program to watch over the members of the cluster (aka nodes), re-booting those that fail to respond. Not a very elegant approach, but its cheap and it works.

Category: Computing
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From Zero To Closed

Published on Sept. 29, 2007 at midnight by XC

Advertisement servers (all of them) are currently so bogged down that they slow down the entire Internet. Google has taken some proactive steps in curing this issue, not many others have done the same.If I can not view a page in 10 – 15 seconds, I close it, period. The delay just tells me that I’m about to deal with a web site that offers more ads than stuff to read, what fun is that?

I don’t discourage making a little money by blogging, in fact I do it. However, try some alternates. Make friends with “Mom and Pop” e-commerce businesses who will genuinally appreciate you promoting them and work with you to develop neat ways to integrate their stuff into your web properties.

I would not buy a newspaper that had more ads than text. Likewise, I’m not going to wait for your page to load to read an article, no matter how interesting it might be, there are 200+ more in my RSS reader to explore. I think, we’ve reached a point where ‘blogeters’ must be more creative or face giving their visitors to someone else. If you write neat stuff, please .. explore other means.

Category: Blogeting

Commercial Kids?

Published on Sept. 29, 2007 at midnight by XC

I make no big secret about my aversion to commercial culture. But, that’s just my aversion. We’ve been approached three times by poeple who wanted to put our two-year-old in commercials.

One commercial was for Pampers, the diaper people. The other two offers focused on more generic/stock use of our daughter’s photographs. We turned all three offers down, just because we felt indecisive. Our golden rule remains, “When in doubt, don’t”. I continue to wonder if we made the best decision.

If you get approached (like we did), I don’t think that there is a right or wrong decision. What remains is the best decsion, this is relative to what you plan to teach your kid. I hope that my daughter puts little value in vanity, becoming a commercial kid might be counterproductive. Yet, what if that’s not who she decides to be? Above all, my daughter is free. She’s free to be whoever she wants so long as my input as a parent has obviously been considered.

These are (and were) our issues:

Someone else has rights too our daughter’s photographs.
Someone else has rights to _sell_ our daughter’s photographs.
Our daughter might not like her baby pictures syndicated (and etched on the Internet forever) at various points in her life.
Being the object of admiration just might go to our daughter’s head.
We ( as parents ) are profiting from a kid who can’t yet fully speak.

Yet I can not help but wonder, what if everything went ‘well’ , am I going to face a future ‘Dad, How could you?!’, time will tell.

Category: Parenting

Web Hosts – Use Jfs Over Ext3

Published on Sept. 28, 2007 at midnight by XC

This is a quick note
Web hosts, try jfs over ext3. I can now report, over a year and counting, every time I clean up a disaster, computers ( virtual or dedicated ) using JFS nearly always recover. Those using ext3 typically suffer database corruption, /etc is missing or corrupted, or some other problem that requires an OS reload.

ext3 is a good file system, the problem is you need to tweak it for proper server usage. I’m not going to blog a tutorial on how to do that, as your idea of usage and mine are sure to differ.

When you order a new server, specify the following:

/boot - ext2 (512 MB should do) - no need to journal here.
/ - jfs (20 GB should do) - you want to journal here, sensibly.
/home - jfs (up to you) - you want to journal here, senisbly
/usr -ext3 (5 GB should do) - This usually remains pretty static, ext3 will do
/tmp -ext2 (2 GB should do) - no need to journal /tmp
/var -jfs (10 GB should do) - you want to journal here, sensibly. If your users are SQL hogs, increase this a bit. The same goes if your users get frequent brute force SPAM attacks.

Most data centers are partition stupid, mostly because requesting something other than / being lumped into one big ext3 piece of junk costs them more on setup. Big data centers use a provisioning system that ‘pushes’ the OS to your machine and sets it up a certain way. Usually, this way is whatever way is ‘default’ for the operating system, typically just one partition.

Category: Rants
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The Blog Capacitor

Published on Sept. 28, 2007 at midnight by XC

How would you like a free service that let you easily show all revisions and edits (versions) of your blog posts? I would. Blogging software (even the all mighty WordPress) does not come ‘out of the box’ with extensive version control. How would you like to never worry about losing your database ever again? Read on
I use the ext3cow file system for many things. The ‘cow’ stands for copy on write, simply put, ext3cow lets you store and access your files ‘as they were’ at some point in history. You do this by accessing your file by its name, then ‘@’, then the date stamp that you want. An example would be something like file.txt@123456789 , as opposed to just file.txt. The @ is fondly called the ‘flux capacitor’ by those who write time traveling tools to manage these types of files.

Lets say you were writing a book. We’ll aptly call this book ‘book.txt’, because, well, its a book and you are using a computer to write it. Lets say, you did a cut and paste operation and completely screwed up chapter 3, not realizing your mistake you hit ‘save’. If you were using ext3cow, you could very easily travel back in time, grab the file just prior to your mistake and copy the un-screwed version of book.txt into the present. Neat, yes?
I fondly refer to anything that changes often, but not obviously as ‘rose red’. The network of blogs active today is one very, very big ‘rose red’. I’ll post (usually) 3 – 5 articles per day, then continue to edit and refine them over the course of a week.

Category: Blogeting
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Pretty, Pretty Good, Or Both?

Published on Sept. 28, 2007 at midnight by XC

There is a common and festering misconception that has existed in users of computer programs ever since there were computers and programs to run on them. “If it is aesthetically pleasing, it must be a good program“. I can not tell you how much you short-change yourself if you have this mentality.

Put simply, aesthetically pleasing just means ‘pretty’. Most of us have gotten used to software that works as a service, something we use with our web browser instead of downloading and running locally. Google Apps is a perfect example of ‘pretty’ and ‘pretty good’ at the same time.

The design and ease of a program’s user interface (what you use to interact with the program) is critical, at no point can anyone dispute this. The program must make its features and functionality easy for the user to command in an intuitive fashion. This, however, is just one critical component. Many people forget, the program must also work
I’ve been working quite a bit on the GNUPanel project, a free software project that aims to produce a free control panel system for web hosts to offer you cheaper web hosting with more reliable features. As I’ve been approaching other developers to see if they would be interested in working on GNUPanel, I’ve been surprised to see that other developers (not just users, developers) have also succumbed to this crazy ‘pretty is always good’ mentality.

Category: Rants
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Xen 3.1.1 Release Candidate 2 Is Out :)

Published on Sept. 28, 2007 at midnight by XC

Oh come, all ye Xenn-ers get the latest rrrr-c. (Ok, I’ll shut up)

Keir has finished assimilating the patch queue into the new release candidate for Xen (3.1.1). There are a plethora of improvements best witnessed by viewing the change log.

I know that many of you prefer to yum or apt-get your way into Xenhood. There’s nothing really wrong with this, however, you should take note of a few things:

You get your OS packager’s version of Xen, not the latest and greatest from XenSource. Every OS packager takes Xen, ‘cherry picks’ patches then does their own voodoo. This is great, but you might want to consider letting your flavor follow the course of development.
Many of the gurus who blog tutorials, tips and tricks for Xen build Xen from source. If you use your OS packager’s version, these resources might not work for you. Debian and Ubuntu do a pretty good job staying ‘close’ to XenSource, others get really picky about including patches from xen-unstable.

At this point, I really recommend having Mercurial installed prior to messing with Xen. 3.1.1 pulls in a slightly different version of the 2.6.18 kernel, see this repository to understand the difference from a stock kernel.org kernel (how it used to work). When you run ‘make’, Xen will want to use Mercurial to pull in that kernel tree then apply the stuff in the sparse tree against it, thus producing your xen-0 and xen-u kernels.

From what I understand, because Xen’s paravirt_ops is now in mainstream Linux (2.6.23-rc8 is a good example), the sparse tree will soon be eliminated. Any kernel.org kernel can easily adapt for the Xen hypervisor, just like VMI ops.

Most of the major changes that I see are for HVM (fully virtualized) guests, plus some stuff to add more BSD compatability and the elimination of a bunch of work arounds. If you have time, give it a try, the Xen developers are looking for feedback.

Category: Xen

Wash Your Ass, Or Was That Watch?

Published on Sept. 28, 2007 at midnight by XC

Toto wants you to do both. No, not Toto the cute little dog, Toto the toilet company.

Sometimes I just chuckle. Toto (A manufacturer of toilets and such other necessities) has made a breakthrough in the ancient art of keeping one’s derrier nice and shiny. Apparently, they have embedded a shower in a toilet seat, but not just ANY shower. In fact, they have launched a bandwidth intense full video / flash site to let us all know that we’re missing out on a more ‘enlightened’ bathroom experience.

Where I come from, rigging a toilet to squirt is a dirty, nasty trick. Many people that I know would agree with me. Then, I moved to Asia (I’ve been here 3+ years). Bidet use is quite common here. Toilet paper is sometimes scarce, why would you need TP when there is a Bidet? I, friends argued with that logic as vehemently as you would.

Let me tell you a story. One day, I had to go. Needing to ‘go’ in south east Asia can be dangerous.
When you gotta go, you gotta go. I found a bathroom, enjoyed my 20 minutes of introspection, then … bah! no toilet paper. To my right I saw a hose, connected to the water supply of the toilet with something that looked like a garden nozzle attached to the top. Oh, dear, I thought as I scrambled to look around the rest room for something that looked like paper, while attempting to keep my ass planted on the toilet. I found myself wishing for three sea shells, if you ever saw “Demolition Man”, you’d get that joke.

Category: Humor
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Hyperactive, Or .. Bored?

Published on Sept. 26, 2007 at midnight by XC

Reflexes are good. Reflexes enable us to do things without thinking, such as pulling our hand away from something that is too hot to touch. Instinct is good, instinct helps us to do things that are good for us (besides the whole business of reproduction, that’s for another post) such as eating and sleeping.

The above, instinct and reflex are known as ‘knee-jerk’ reactions. Think about a doctor hitting your kneecap in just the right place with a rubber hammer. Your leg kicks, neat huh?

When we can afford thought to our reactions, we should spend thought on them, its free. This is why we’re on the top of the food chain. I want to take a moment and call into question anyone who prescribes medicine for ‘hyperactivity’ or ‘attention deficit disorder’ in children as a knee-jerk reaction. I was reading some things that alarmed me on some of the on-line parenting communities that I subscribe to.

Depending on your health insurance, you will go to whatever clinical psychologist or psychiatrist that your ‘health network’ permits. Likely, you’ll be seeing someone who has a waiting room full of people with very little time to spare. Be kind, ensure that you don’t take up too much of this person’s time, here’s how to help:
Don’t come in with a pre-diagnosed kid, especially if you are the one who did the diagnosing. What you’ll do is convince your doctor that your child has a certain problem and out the door with meds you’ll go.

Category: Parenting
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Linux 2.6.23-Rc8 Looks Good!

Published on Sept. 26, 2007 at midnight by XC

I grabbed a copy of 2.6.23-rc8 today and spent a couple hours configuring the build. There has been quite a few grumbles about the Linux kernel leaving ‘old’ hardware in the dust. So what, to my wondering eyes did appear to my old Pentium 4 and 8 tiny reindeer?

Kconfig (aka make menuconfig) seems a bit more organized. The last trees I was working with were 2.6.18 and 2.6.20.3 – I breezed through the configuration after a make defconfig rather quickly.
Less latency overall using the default scheduler.
Several needed improvements to ocfs2 (YAY)
Lots, and lots of ACPI fixes, suspend/resume on my machine seems to work without a hitch now. This was really annoying, every time my machine woke up, it woke up angry.
Lots and lots of virtualization options with much better help in kconfig, this is not news we all knew it was coming, but its neat to see Xen paravirt_ops in a kernel.org release.
Boot time was literally cut in half from my previous 2.6.20.3 (I use that tree often because its the one officially supported by ext3cow)

Now, on to the gripes :

Its too damn stable. No fun.
Either udev, or the kernel have some sort of issue. 2.6.23 gives me warnings that no buffer space is available, only during udev events. I’m inclined to think its not udev. I made this go away in 2.6.20.3 by taking out all of the debug and noisy stuff, then I got to see my udev warnings again. This has been reported with many newer kernels, in particular with Ubuntu’s udev package.

Category: Linux
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