Tuesday November 15, 2005

Pedal your way to a cheaper lunch? A new chain of restaurants in the Bay area has proposed that they will give discounts to customers who are willing to ride stationary bicycles connected to a generator, helping to power the restaurant. Hmm, I am not seeing a downside to this. Burn calories + help the environment = get cheaper food. That's awesome!

It still irritates me, when I go to the gym, that I am wasting my energy on meaningless units of work. If the technology was feasible, it would be great to start a gym that could harnesses most of the energy expended by the patrons and sell it to other businesses. Then, you could give discounts to the people who generate the most joules:)
(2005-11-15 09:06:38.0) Permalink Comments [3]

Tuesday October 25, 2005

How-to for Zones If you have never used Zones and would like to start playing with them, I really liked this how-to article. Although the article is targeted towards Apache users, the majority of the topics cover general information about administering Zones. Thus, it would be useful as a beginners guide or as a quick reference for Zones.


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Technorati Tag: Solaris (2005-10-25 08:48:56.0) Permalink Comments [0]

Friday August 26, 2005

My tipping point I finished reading "The Tipping Point" by Malcolm Gladwell last week. Although, I found some of the topics in the book interesting, in general I felt frustrated with what I perceived to be a lack of completeness with some of the author's theories. My tipping point from frustration to flat out irritation came with the following example. In this example the author attempts to reference research by Leda Cosmides into human cognition and the effects of context.

     Suppose four people are drinking in a bar.  One is drinking Coke. One is sixteen. One is drinking beer and one is twenty-five. 
     Given the rule that no one under twenty-one is allowed to drink beer, which of those people's IDs do we have to check to make
     sure the law is being observed? ("The Tipping Point", MG, pg159)

Hmm, well, assuming that the one who is drinking Coke is only drinking coke, then I would have to go with the one who is drinking beer, as they are the only individual drinking beer, whose age is unknown. But, wait..there's more! Lets see what Mr. Gladwell's answer is:

     Now the answer is easy. In fact, I'm sure that almost everyone will get it right: the beer drinker and the sixteen-year-
     old. ("The Tipping Point", MG, pg160)

Wow, don't I feel like an addlepated infant! The sixteen-year-old? Are you sure? But don't we already know how old they are? How would it be useful to check their ID? Wouldn't it be more constructive to check what they are drinking?
*sigh*
If an author doesn't feel like paying attention to details, then it would be nice if they could at least refrain from using statements like "Now the answer is easy" or "almost everyone will get it right". (2005-08-26 10:50:13.0) Permalink Comments [8]

Wednesday August 17, 2005

1st frosug meeting The first Front Range OpenSolaris User Group(frosug) meeting was held here in Broomfield, CO last Thursday. Jim Walker and Stephen O'Grady did a nice job of covering the meeting in their blog entries. There were ~20 developers from Sun that attended the meeting. I was pretty excited about the overwhelmingly enthusiastic response from Solaris developers, which seems to bode well for the success of OpenSolaris:-)

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Friday August 05, 2005

Fun with state database replicas (Part 1) As I mentioned in my last entry, information about SVM metadevices is stored in state database replicas(mddbs). The data structures used in state database replicas are defined in: usr/src/uts/common/sys/lvm/md_mddb.h
The following is a drawing of diskset mddb:

1) The Master Block

The master block contains two important pieces of information, a unique device identifier(devid) and the offset for the locator block.* The devid is used by SVM to track the drives that are in a set--so that SVM can handle changes in their physical location. The master block contains the mapping from a logical block 0 to the physical offset for the mddb's locator block. If there are two mddbs on the same slice, they will each have a different master block--the location of the first metadb will be at 0 and the second at 8192. The master block and locator block are the only two parts of an mddb who's location always remains constant. All drives in a diskset either contain a mddb or a dummy master block. The dummy master block is primarily used to store the devid for the drive.

* In replicated disksets, the master block does not have a devid for the drive it is on, rather it contains a copy of the devid for the original drive.

OpenSolaris
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Tuesday June 14, 2005

A new entry Soo apparently...a blog is suppose to contain multiple entries! Well, at least now, my blog has two entries--even if they are separated by about a year;-)
Since, I neglected to mention it in my first post, I will start with a bit of background on myself. I have been working as a developer with the Solaris Volume Manager(SVM) team for the last 1.5 years. My first assignment involved assisting with testing for the metaimport project. After the project was completed and backported to Solaris 9, I helped the other SVM engineers stabilize the SVM codebase for the Solaris 10 launch--i.e. fixed bugs. I am currently working on a project to extend some of the current functionality in SVM.

For those of you who are interested in learning more about SVM, I recommend that you at least scan the SVM documentation for system administrators. Since, I will be mentioning terms from the Solaris Volume Manager in my blog, I thought it might be helpful to briefly cover some of the concepts and the terms that we use internally to describe them.

• Logical Volumes
  • Logical volumes are used to manage physical devices and the associated data. These are also referred to as virtual disks or metadevices. SVM supports the following types of logical volumes(metadevices): stripes/concats, mirrors, soft partitions, hotspares, and raid5.
• Disksets
  • Disksets are used to group metadevices. Sets have their own state database replicas that contain information about all of the metadevices within the set. By default metadevices are placed in the local diskset, unless a specific set is specified. Specific sets are also called traditional disksets or shared disksets. There are also multi-owner(or multi-node) disksets, which are the only type of diskset that can be accessed by multiple hosts at the same time and are typically used with the Sun Cluster product.
• State database replicas
  • Information about all SVM metadevices is stored in state database replicas. These are also referred to as metadatabases or mddbs. These state database replicas(mddbs) typically exist in two places: on disk and in the kernel. In order to use SVM you must have created at least one mddb for the local set. The kernel keeps a copy of all active mddbs. These are referred to as the incore mddbs. The maximum size, which also happens to be the default size for a mddb(traditional or local set) is 4MB. The namespace for a diskset supports metadevice entries from d0 through d8191(not including hotspare pools).

OpenSolaris
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Friday July 16, 2004

extinction? Fiercely clever paleontologists have been predicting Sun's demise for several years. When I first joined Sun as a new college grad, I was advised, "it is nie unto the end of the Cretaceous period!" But hey, I figured that given the times just having a job put me ahead of the curve. In the past six months, however, I have come to realize that Sun, as a company, possesses an incredibly rare ability--that of adaptation. So although, the field of computer technology may indeed be entering the Palaeogene period, Sun can and "is" evolving to meet the new challenges! This evolution is evident in the soon-to-be shipping product, Solaris 10. Many of the new technologies in Solaris 10 are redefining the function and abilities of an Operating System. Some examples are Dtrace, Zones, and Predictive Self-Healing. There are interesting times ahead, so buckle your seatbelt and hang on. (2004-07-16 15:00:48.0) Permalink