The Treehouse Blog » Technology

Upgrade Fedora 15 to Fedora 16

balleman — Fri, 30 Dec 2011 01:29:44 +0000

The desktop upgrade from Fedora 15 to Fedora 16 was about on par with the upgrade from 14 to 15. Instead of the disaster that is Gnome 3, we’re instead greeted with GRUB 2 and new systemd quirks.

The main portion of the upgrade itself went smoothly. No unexpected surprises from anaconda until the notice that the bootloader didn’t install right.

GRUB 2

So apparently Fedora 16 incorporates GRUB 2. While its error messages seem far friendlier than GRUB classic, I really did not delve into all of its supposed benefits. One downside is that when built with RAID support (which I seem to need since my /boot partition is mirrored), the core.img file ends up >32KiB, and thus does not fit in the post-MBR gap present on my drives.

To address this, I used a gparted live CD and resized and moved the first partition of each drive (which happen to be NTFS drives for my Windows 7 install, one of which was the system volume). This provided a 2MiB gap between the MBR and first partition. Booting back into the Fedora 16 rescue mode and using grub2-install on both drives successfully installed GRUB2 and, following a reboot, allowed Fedora 16 to load.

Unfortunately, these partition table and file system hijinks left Windows 7 with a bit of a problem, seeing as it would not boot. The recommended method of using the Windows 7 installer’s “Startup Repair” feature was unsuccessful. The “bootrec /fixboot” would not fix it, giving an “unsupported filesystem” error. Using diskpart to set the Windows partition to active appears to resolve this, and the fixboot succeeds. Naturally, I ran fixmbr at some point, which wiped out GRUB again, and thus it had to be reinstalled. Success with booting both Windows 7 and Fedora 16 was then achieved.

NFS mount

The machine has one NFS share mounted via /etc/fstab. After the upgrade, this would fail to mount during boot, but would have no difficulty being manually mounted after boot. After researching a variety of wrong paths with various systemctl changes, the one I found to resolve this was “systemctl enable NetworkManager-wait-online.service”.

Update 1/8:

The upgrade of my HTPC wasn’t too painful. Mucked with partitions to make room for GRUB2 ahead of time, had to change my lirc init script to not confuse systemd, disable screensaver in gnome 3 (yes, shouldn’t be using gnome to run mythtv – need to add that to the list), re-enabling services that weren’t automatically figured out from existing init scripts, switched mounts from /dev/md* to UUID-based to get the ordering right in the new boot sequence, mythtv ownership changes, etc, etc.

GraphViz

balleman — Fri, 13 Aug 2010 01:31:12 +0000

A while back I had to diagram interactions between components in a KRB5+LDAP+NFS4 system. Instead of laying this out by hand, I went with GraphViz. I think I had known of its existence, but when I forget what the name of it is, I tend to look up this diagram of Ender stories from Wikipedia. The diagram I made is below, if you happen to have a Celerra laying around. Recently, I’ve started playing with GraphViz again to do some stuff for my current job, but have found out that one thing it doesn’t really do are the directory-tree type layouts one expects to find in most file managers today. Maybe they’ll add that as a different layout engine at some point.

DNSSEC at home

balleman — Sun, 18 Jul 2010 02:26:47 +0000

Since the root zone was signed this week, I spent a bit of time today setting up DNSSEC validation on my home recursive server. It was relatively painless (so far). I did opt to not enable DLV though – not fond of it receiving every host name I resolve.

Resources:

RHEL RPMs from http://people.redhat.com/atkac/bind/5.6-test/ – if someone finds a better source for BIND 9.7+ RHEL RPMs, I’d like to know. I had no luck building from the Fedora SRPMs.
http://www.isc.org/community/blog/201007/using-root-dnssec-key-bind-9-resolvers – instructions for setting up BIND to use the root key.
http://fanf.livejournal.com/107310.html – A more thorough walk-through of setup.

One resource I would have liked to find and could not was a deliberately unvalidatable non-root zone/record that could be used to see a validation failure. If anyone knows of or finds such a thing, please pass it along. Now we get to wait for .com, .net, etc, to catch up to .bg and .uk in the publishing of DS glue for deeper validation.

UPDATE 7/22/10: Just found the following site which makes available bad records for testing purposes: http://dnssec-tools.org/testzone/index.html

Device Convergence: GPS

balleman — Wed, 02 Jun 2010 01:37:25 +0000

Are cell phones yet to the point where they can replace a hand-held hiking GPS? Up until recently, I’ve been quick to dismiss this notion. The announcement of Garmin’s latest hand-helds that appear to be moving closer to their cell phone brethren has me wondering. Reports of the new touch-screen interface are about as bad as one would expect.

So, what are the issues? I tried my G1 running OruxMaps on a 3.5hr / 10 mile hike in the mountains on Monday to get a better perspective.

Battery Life. It barely survived. I would probably expect twice the battery life from my Garmin GPSMap 76S with a constantly running display. Can the battery life issues be solved with an external AA-based battery pack to keep the cell phone charged? I have no experience with these things. Reviews indicate that ones without regulators aren’t worth much. I might have to try one.

GPS Hardware. Cell phones may have GPS receivers, but it is not their primary function. Most Android phones I’ve looked at seem to use the Qualcomm gpsOne chipset instead of a dedicated chipset such as the oft-mentioned SiRFstar III. This is a cause for concern, since gpsOne currently seems to lack support for WAAS and likely is not as sensitive as the SiRFstar. The upside of gpsOne is that AGPS will provide a faster lock when within range of the cell network.

Usability. Another major hurdle is the availability of high quality GPS software for the phone. I’ve tried Maverick Lite, OruxMaps, and My Tracks and found them all to be lacking the necessary features of a hand-held GPS. My Tracks is the Google-sponsored outdoor activity tracking app that was very recently open-sourced. Maverick and Orux both provide offline map access (another must), but they seem to accomplish this with saved graphic tiles and not vector data as would be desired. Any new GPS solution I get should have high-resolution topo maps included.

Durability. Hand-held GPS receivers tend to be waterproof and a bit rugged. I’ve dropped my GPSmap 76s a number of times – and it once fell off my bike at 15+ mph. There’s no way any phone I’ve owned would be happy with that kind of treatment.

Bottom line? Not sure yet. I do think the concept of a hand-held GPS is already starting to fade. I’m not ready just yet to give mine up in favor of the cell phone. I hope the newly open-sourced My Tracks starts gaining some useful hand-held features.

Tales of X10

balleman — Sat, 29 May 2010 00:40:06 +0000

A few years ago, I decided to improve the light switch situation in my garage. The garage had lights at either end controlled by pull strings. It was a frequent hassle to walk from one end to the other, often tripping over a variety of obstacles, to get both of them on or off. Having already deployed X10 to control a few things around the house, it seemed like a reasonable and economical idea to use X10 here as well. I used two LM15As for load switching, two SS13As for control near both doors in the garage, and an RR501 to tie everything together. Initially, the project seemed to be a great success.

Then it becomes apparent that the SS13As are not that great. The adhesive backing would refuse to stick to the garage wall for extended periods of time, necessitating the addition of some screws to provide a slight ledge for them to sit upon. They are also battery powered, and the stock batteries were nearly useless in cold weather. Naturally, the colder times of year require the use of lights in the garage more often, and it became incredibly annoying to have to warm the switch with your hand and make multiple attempts to turn on the light… when the pullstring that otherwise would work is in reach. My suggestion is to never use SS13As in anything but warm environments, and probably just avoid them altogether. The one I had used inside would “forget” its code assignments and the coldness of the window sill was enough to keep it from working well.

To fix these issues, I revisited the idea of wiring regular three-way switches in the garage. With the layout of the existing wiring, even the most creative ideas would require two new wires run the length of the garage, with one of them likely needing to be a 3-conductor that I don’t happen to have laying around. And copper isn’t really cheap right now. So, X10 was again looked at for a solution.

I decided to go with hard-wired X10 controllers, specifically the XPT4-W. I installed these near existing wire locations with a minimal of effort – maybe 3 hours total. So, now I have fully functional control of my garage lights (probably even in cold weather), and didn’t need to run crazy amounts of cable for three-way switches.

Isn’t AMPS dead yet?

balleman — Tue, 11 May 2010 01:21:33 +0000

It was with some great fanfare that AMPS met its death on February 18th, 2008. But did it really die? As far as I can tell, all that happened on that date was that the FCC no longer required cellular providers to make AMPS available, and many did eagerly turn it off. But, unlike the conversion to digital television, there appears to be no requirement at this point for providers to abandon AMPS if it is still making them money. That being the case, are there any AMPS providers still out there? Public filings (available here) concerning AMPS status were made prior to the sunset date and reveal that some companies had a lot of AMPS customers still and had no plans to turn the service off.

Why do I care? Because I loathe 47 CFR 15.121 and would like to see it abolished. This is the section of FCC regulations that forbids the manufacture of devices that can receive, or be easily modified to receive, cellular frequencies. This requirement only covers the Part 22 Cellular Service (824-849, 869-894 MHz) and not the all-digital PCS and AWS bands that cell service has expanded into. With AMPS, conversations were transmitted using FM, and so could be easily decoded by any FM receiver that could tune to the appropriate frequencies. With the digital services, more sophisticated handling of the signal (and even decryption) would be required, which apparently made it unnecessary to have the same kind of regulation. As far as I know, this is the only restriction placed on what frequencies can be tuned by a receiver. On freedom grounds alone, I have a big problem with that. If AMPS does finally die – and I hope it does – I hope that 47 CFR 15.121 can die with it.

Missing L3 Hut Found (demolished)

balleman — Sun, 11 Apr 2010 19:31:11 +0000

While hiking this weekend partly along the suspected area of the long-since-defunct Bedford-Harrisburg L3 cable, I found the apparent demolished remains of one of the repeater huts that had eluded me up to this point. As they all are, it was not far off the road, near the top of the mountain at Upper Strasburg. Guard rails have since been erected in front of what would have been it’s very small level parking area. Nearby there were also portions of exposed L3 cable that had apparently been covered in rocks instead of buried below grade. Really awesome, though unintentional, finds!

The map has been updated.

Demolished L3 Repeater Hut

Exposed L3 cable

Power vs. Energy

balleman — Fri, 09 Apr 2010 02:03:32 +0000

I’m trying to catch up on some reading, and am working through a number of articles concerning energy sources, the power grid, and so forth. One almost constant source of annoyance I find in these articles is that the difference between power and energy are either ignored, misused, or left hopelessly ambiguous. The writers are not totally to blame, since our vocabulary for discussing these concepts is weak and it takes a lot of effort to clearly convey the correct meaning. Consider the following example:

The U.S. electric system has 2.5 gigawatts of pumped hydro storage capacity.

“Capacity” when used to discuss an energy storage apparatus can have two meanings. It could mean the power capacity of the system, which is the amount of energy that can be released from storage and converted to electricity instantaneously. For pumped hydro storage, this would be determined to a large degree by the size of the turbines, generators, and penstocks. This quantity represents, for instance, the number of lights a plant could handle without dimming – it says nothing about how long it could keep them lit. A common unit of power capacity is gigawatts.

The other type of “capacity” is the energy storage capacity of the system. For pumped hydro storage, this is the value related to the size of the water reservoir. This is the quantity that represents how long a plant could keep a given number of lights lit, for instance. A common unit of energy capacity is gigawatt-hours.

Assuming the author chose the units correctly, this quote tells us that the power capacity of US pumped hydro is 2.5 GW. Unfortunately, something isn’t right, because the Energy Information Administration says the number is actually 20 GW.

Consider another example:

The Norton project could store 2.7 gigawatts of power in an abandoned limestone mine.

I’m afraid this one is beyond redemption. You don’t store power, you store energy. But the units given are for power, and from further research in other articles, the power capacity of the plant is expected to be 2.7 gigawatts. I was not able to find a source that estimated the plant’s energy storage potential.

Any time you read the words “power,” “energy,” or “gigawatt” in an article, read it very critically. The commonly cited statistics for power plants are always their power capacity, and even for energy storage plants, storage capacity is seldom stated. One likely reason is that power capacity is relatively easy to determine – it is likely written on a nameplate on the generator somewhere. Calculating the energy capacity of a storage facility would be more challenging, and might not be a number required by regulators – and hence one that is seldom available.

Both quotes are from this wired.com article, but many articles discussing energy storage have the same problem.

TM-D710A Transmit Inhibit

balleman — Wed, 07 Apr 2010 03:20:48 +0000

I did recently get a TM-D710A and have been playing around with it. I have found one missing feature that would be nice, and a workaround for it. Suppose you want to add an amateur frequency as a memory channel for listening/scanning purposes only, but don’t want to ever accidentally transmit on that channel. I think it would make sense to have a flag that could be set on a per-channel basis to inhibit transmission on that channel, but unfortunately there is not. I have come up with a viable workaround though. It is possible to configure a memory channel as “split” – with a receive frequency and a separate transmit frequency. It is required that both frequencies be on the same band… though I’m not sure why – this would be a useful feature as well, so that one does not need to tie up both sides of the radio for half-duplex cross-band applications. Anyway, it is possible to configure the transmit frequency to be within the same band and still outside of the portion of the band which the radio can transmit on. This results in a beep and no transmission when PTT is pressed – which would be exactly the desired behavior of a transmit inhibit flag.

G1/Linksys Wifi Problems

balleman — Sun, 14 Mar 2010 00:54:22 +0000

Awhile ago I finally upgraded my home wireless network (a single WAP54G v2) from TKIP to AES. This has been something on the to-do list since I got rid of the Axim (which wouldn’t support AES). I tested my two wireless client devices – a laptop and my G1, and they seemed fine at the time. All was well.

Later I noticed that the G1 was not functioning on my home network, yet worked on other similarly secured networks I connect to. It would connect, obtain an IP address, but not pass traffic – which is a pretty bad scenario since the G1 wouldn’t automatically fail back to its GSM data connection. I did the typical troubleshooting with “forget”-ing the network and reconnecting, etc, but this was unsuccessful. More detailed analysis showed that almost immediately after DHCP completed successfully, the G1 would see no traffic generated from the network, and the network would see no traffic generated by the G1. With the laptop working fine through all of this, it really seemed to be a problem with the G1.

After essentially exhausting other options, I turned my attention to the WAP. I tried changing the SSID which didn’t help, and reverting back to TKIP, which worked fine. I then decided to upgrade the WAP’s firmware, from 2.07 (2004 era) to 3.04 (2005 era – still 5 years old!). The wireless security settings are more granular than the former version – and after reconfiguring – the G1 works on AES.

Hopefully this time it will keep working.