Uncompressing Cisco X2000 firmware images

I got a refurbed Cisco X2000 [amzn] ADSL router / wireless access point for cheap from Adorama, hoping to combine 2 networking boxes, and reduce clutter and power a bit.  It comes in at 3-4W, and has an efficiency Level V wall wart, so that part’s all good.

Edit: Everything else is bad!  Don’t get this device.  Really.  It’s the buggiest piece of junk I’ve had the misfortune of trying to run on my network.  I’ll leave the rest of this post here for posterity.

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Spinning down a WD20EARS “Green” drive

Ok, this is a pretty utilitarian post.  I did finally get my 18W Server up and running; in fact, it’s serving this post!  But I can’t really get to 18W unless the 2x 2T WD20EARS [amzn] drives I have in it for media storage spin down when not in use.

And I had a heck of a time making that work.  hdparm -y would quickly spin them down, but using hdparm -S to set an idle timeout seemed to have no effect; I had been trying to use hdparm -S 241 to set a 30 minute spindown time, and I had no luck whatsoever.  With the drives spinning, the server used more like 30W.

Mostly through trial and error, I found out that if you set a lower spindown timeout, i.e. hdparm -S 3, the drive will spin down in 10 minutes. Continue reading

Heating with a Mini-Split? Looking at costs & emissions.

My previous post was about our Mini-Split A/C unit, purchased to get us through the few weeks of >100F weather we had this summer in the Twin Cities.  But the post also alluded to the ability of these units to heat.  Now that it’s cooling off, let’s take a look at that.

What these units do is move heat.  Amazingly, they can move it in either direction!  In the summer, they move heat out of the house, obviously enough, just like any A/C.  But in the colder months, they can move heat into the house as well.  Even when it’s cold outisde, you ask?  Yep!  How is that possible? Continue reading

Comparing PVWatts Estimates to Actual Solar Production

Click to enlarge

PVWatts is a website run by the National Renewable Energy Lab (NREL) which can be used to estimate how much energy a given solar array might produce, based on historical mesurements of insolation.  If you ever have a site analysis done, the installer will probably use it to estimate your potential for annual production, and you might wonder how close the the mark it’ll be.  Now that I’ve had solar PV for almost 2 years, it’s interesting to look at how close the estimates were for my situation. Continue reading

Linux Filesystems LOC Update

I did a post last year about how lines of code for some of the primary Linux filesystems were evolving.  It seemed to spark people’s interest, so here’s an update through v3.4-rc4:

(Click to see full size).

I added regression lines this time – btrfs should catch xfs around kernel version 3.8 or so.  :)

Again, I draw no strong conclusions from this – I just think it’s interesting to see how things are moving as these filesystems evolve.

I used CLOC to count lines; the numbers on the graph reflect no blank lines & no comments.  For ext3 & ext4 I included jbd[2] and some of the peripheral files they use; code snippet from the script:

ext3lines=`cloc fs/ext3/*.[ch] include/linux/ext3*.h  fs/jbd/*.[ch] \
           include/linux/jbd.h fs/mbcache.c include/linux/mbcache.h \
           | grep SUM | awk '{print $5}'`;
ext4lines=`cloc fs/ext4/*.[ch] include/linux/ext4*.h  fs/jbd2/*.[ch] \
           include/linux/jbd2.h fs/mbcache.c include/linux/mbcache.h \
           | grep SUM | awk '{print $5}'`;
xfslines=`cloc fs/xfs/*.[ch] fs/xfs/*/*.[ch] include/linux/dqblk_xfs.h \
           | grep SUM | awk '{print $5}'`;
btrfslines=`cloc fs/btrfs/*.[ch] | grep SUM | awk '{print $5}'`;
gfs2lines=`cloc fs/gfs2/*.[ch] include/linux/gfs2* \
           | grep SUM | awk '{print $5}'`;

(Some of the files above no longer exist, but I used the same script to iterate over all the kernel versions.)

Opower goes social

I wrote about Opower almost 2 years ago, a company which is working to reduce energy use by simply making people more aware of what they use in comparison with others.  At the time of that post, they seemed mostly focused on working directly with utilities, and sending out reports to customers showing them how their energy use compared to similar homes in their area.  The idea seems to be that if you are at all conservation & efficiency minded, seeing where you are in relation to others may actually encourage you to do even better.  They track the results, and apparently, it works.  However, that method works only if the utility is on board to provide the data. Continue reading