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Colin Charles: Amazon EC2 Linux AMIs

Fri, 2014-04-11 01:26

If you use Amazon Elastic Compute Cloud (EC2), you are always given choices of AMIs (by default; there are plenty of other AMIs available for your base-os): Amazon Linux AMI, Red Hat Enterprise Linux, SUSE Enterprise Server and Ubuntu. In terms of cost, the Amazon Linux AMI is the cheapest, followed by SUSE then RHEL. 

I use EC2 a lot for testing, and recently had to pay a “RHEL tax” as I needed to run a RHEL environment. For most uses I’m sure you can be satisfied by the Amazon Linux AMI. The last numbers suggest Amazon Linux is #2 in terms of usage on EC2.

Anyway, recently Amazon Linux AMI came out with the 2014.03 release (see release notes). You can install MySQL 5.1.73 or MySQL 5.5.36 (the latter makes the most sense today) easily without additional repositories.

The most interesting part of the release notes though? When the 2014.09 release comes out, it would mark 3 years since they’ve gone GA with the Amazon Linux AMI. They are likely to remove MySQL 5.1 (its old and deprecated upstream). And:

We are considering switching from MySQL to MariaDB.

This should be interesting going forward. MariaDB in the EC2 AMI would be a welcome addition naturally. I do wonder if the choice will be offered in RDS too. I will be watching the forums closely

Related posts:

  1. A Storage Engine for Amazon S3
  2. Some MariaDB related news from the Red Hat front
  3. MariaDB & distributions update, Dec 2013

Andrew Pollock: [life] Day 72: The Workshops, and zip lining into a pool

Thu, 2014-04-10 22:26

Today was jam packed, from the time Zoe got dropped off to the time she was picked up again.

I woke up early to go to my yoga class. It had moved from 6:15am to 6:00am, but was closer to home. I woke up a bunch of times overnight because I wanted to make sure I got up a little bit earlier (even though I had an alarm set) so I was a bit tired.

Sarah dropped Zoe off, and we quickly inspected our plaster fish from yesterday. Because the plaster had gotten fairly thick, it didn't end up filling the molds completely, so the fish weren't smooth. Zoe was thrilled with them nonetheless, and wanted to draw all over them.

After that, we jumped in the car to head out to The Workshops Rail Museum. We were meeting Megan there.

We arrived slightly after opening time. I bought an annual membership last time we were there, and I'm glad we did. The place is pretty good. It's all indoors, and it's only lightly patronised, even for school holidays, so it was nice and quiet.

Megan and her Dad and sister arrived about an hour later, which was good, because it gave Zoe and I a bit of time to ourselves. We had plenty of time on the diesel engine simulator without anyone else breathing down our neck wanting a turn.

The girls all had a good time. We lost Megan and Zoe for a little bit when they decided to take off and look at some trains on their own. Jason and I were frantically searching the place before I found them.

There was a puppet show at 11am, and the room it was in was packed, so we plonked all three kids down on the floor near the stage, and waited outside. That was really nice, because the kids were all totally engrossed, and didn't miss us at all.

After lunch and a miniature train ride we headed home. Surprisingly, Zoe didn't nap on the way home.

Jason was house sitting for some of his neighbours down the street, and he'd invited us to come over and use their pool, so we went around there once we got back home. The house was great. They also had a couple of chickens.

The pool was really well set up. It had a zip line that ran the length of the pool. Zoe was keen to give it a try, and she did really well, hanging on all the way. They also had a little plastic fort with a slippery slide that could be placed at the end of the pool, and the girls had a great time sliding into the pool that way.

We got back home from all of that fun and games about 15 minutes before Sarah arrived to pick Zoe up, so it was really non-stop day.

Andrew Pollock: [life] Day 71: Tumble Tastics trial, painting and plaster fun

Wed, 2014-04-09 21:26

Zoe slept in even later this morning. I'm liking this colder weather. We had nothing particular happening first thing today, so we just snuggled in bed for a bit before we got started.

Tumble Tastics were offering free trial classes this week, so I signed Zoe up for one today. She really enjoyed going to Gold Star Gymnastics in the US, and has asked me about finding a gym class over here every now and then.

Tumble Tastics is a much smaller affair than Gold Star, but at 300 metres from home on foot, it's awesomely convenient. Zoe scootered there this morning.

It seems to be physically part of what I'm guessing used to be the Church of Christ's church hall, so it's not big at all, but the room that Zoe had her class in still had plenty of equipment in it. There were 8 kids in her class, all about her size. I peeked around the door and watched.

Most of the class was instructor led and mainly mat work, but then part way through, the parents were invited in, and the teacher walked us all through a course around the room, using the various equipment, and the parents had to spot for their kids.

The one thing that cracked me up was when the kids were supposed to be tucking into a ball and rocking on their backs. Zoe instead did a Brazilian Jiu-Jitsu break-fall and fell backwards slapping the mat instead. It was good to see that some of what she learned in those classes has kicked in reflexively.

She really enjoyed the rope swing and hanging upside down on the uneven bars.

The class ran for 50 minutes (I was only expecting it to last 30 minutes) and Zoe did really well straight off. I think we'll make this her 4th term extra-curricular activity.

We scootered home the longer way, because we were in no particular hurry. Zoe did some painting when we got home, and then we had lunch.

After lunch we goofed off for a little bit, and then we did quiet time. Zoe napped for about two and a half hours, and then we did some plaster play.

I'd picked up a fish ice cube tray from IKEA on the weekend for 99 cents (queue Thrift Shop), and I bought a bag of plaster of Paris a while back, but haven't had a chance to do anything with it yet. I bribed Zoe into doing quiet time by telling her we'd do something new with the ice cube tray I'd bought.

We mixed up a few paper cups with plaster of Paris in them and then I squirted some paint in. I'm not sure if the paint caused a reaction, or the plaster was already starting to set by the time the paint got mixed in, but it became quite viscous as soon as the paint was mixed in. We did three different colours and used tongue depressers to jam it into the tray. Zoe seemed to twig that it was the same stuff as the impressions of her baby feet, which I thought was a pretty clever connection to make.

After that, there was barely enough time to watch a tiny bit of TV before Sarah arrived to pick Zoe up. I told her that her plaster would be set by the time she got dropped off in the morning.

I procrastinated past the point of no return and didn't go for a run. Instead I decided to go out to Officeworks and print out some photos to stick in the photo frame I bought from IKEA on the weekend.

Colin Charles: Book in Korean: Real MariaDB

Wed, 2014-04-09 21:26

For some months now, there have been some back & forth emails with Matt, one of the senior DBAs behind the popular messaging service, KakaoTalk (yes, they are powered by MariaDB). Today I got some positive information: the book published entirely in the Korean language, titled Real MariaDB is now available.

It covers MariaDB 10.0. Where appropriate, there are also notes on MySQL 5.6 (especially with regards to differences). This is Matt’s fourth MySQL-related book, and there’s a community around it as well. The foreword is written by Monty and I.

If you’re reading the Korean language, this is the manual to read. It should push MariaDB further in this market, and the content is relatively quite advanced covering a lot of optimization explanations, configuration options, etc. At 628 pages, it is much, much better than the Korean translation of the Knowledge base!

Related posts:

  1. Book: MariaDB Crash Course
  2. MariaDB 5.1.44 released
  3. MariaDB 5.1.42 released!

TasLUG: Hobart April Talk: The open-source graphics train wreck

Wed, 2014-04-09 18:26
Welcome to April already! Last month's talk on OpenDCP had a great reception, and I hope you're all not too busy getting new keys after that OpenSSL Heatbleed vulnerability.



NOTE: for this month only, TasLUG in will be meeting in the downstairs room at SoHo rather than upstairs.



When: Thursday, April 17th, 18:00 for an 18:30 start

Where: DOWNSTAIRS, Hotel Soho, 124 Davey St, Hobart. (Map)



Agenda:



  • 18:00 - early mingle, chin wagging, etc
  • 18:30 - Question and answer session, News of Note.


  • 19:00 - Mathew Oakes - The open-source graphics train wreck



    train wreck

    1.

    a chaotic or disastrous situation that holds a peculiar fascination for observers.

    "his train wreck of a private life guaranteed front-page treatment"



  • 20:00 - Meeting end. Dinner and drinks are available at the venue during the meeting.




We will probably get to a discussion on the Hobart LCA 2017 bid, ideas for upcoming Software Freedom Day in September, the Statewide meetup, Committee nomination and voting, so our pre-talk discussion should be packed full of jam.

Note for May: There will be no Hobart meeting next month in May - instead we should all be heading to our statewide meetup at Ross! If you need a lift, contact one of us on the mailing list or IRC so many of us can get along and bring your open source stuff to show off!





Also in April:

26th - Launceston meeting

May:

24th - Statewide Meet-up - Ross Town Hall

June:

19th - Hobart: No talk scheduled, idea being thrown about to make it an OpenStack short talk night.

July:

11-13th - Gov Hack 2014 - There's at least a Hobart venue for this event.

September:

20th - Software Freedom Day - events in Hobart and Launceston

Andrew Pollock: [life] Day 70: Visiting relatives and home visiting doctors

Tue, 2014-04-08 22:26

Zoe did indeed sleep in this morning, by a whole 30 minutes. It was nice. She seemed no worse for wear for her lip injury, and it was looking better this morning.

Wow, "bimonthly" is ambiguous. I had my "every two month" in person co-parenting sync up lunch with Sarah today. Phew, that was a mouthful. Anyway, I had that today, and normally that would fall on a Kindergarten day, but it's school holidays. So we paid grandma and grandpa a visit, and they looked after Zoe for me so I could make the meeting.

Mum and Dad have been away on a driving holiday, so Zoe hasn't seen them for a while, and it's been even longer since we've been to their house. She really loves going to their house because it's big, with a big back yard with a swing set. There's all sorts of exciting things like grandpa's worm farm, a sand pit, a china tea set, a piano, a tricycle and remote controlled cars. Zoe basically just works her way around the house entertaining herself. It's great. I usually get to put my feet up and read the newspaper.

After I got back from my lunch meeting, we headed over to Greenslopes Private Hospital to visit my cousin, who's just had major surgery. On the way, Zoe napped in the car. I made a brief side trip to clear my post office box along the way.

Amusingly, Zoe wakes up from short naps in the car way better than at Kindergarten. I don't know if it has anything to do with the quality of sleep she's getting or what it is, but I easily woke her up and extracted her from the car when we arrived at the hospital. No meltdowns. And that's pretty typical of car naps.

I've had a discomfort in my right ear for the last couple of days, and it grew into increasing pain throughout the day today. It got to the point where, while I was driving home, that I deciding to get it looked at by a doctor, ASAP. One of my favourite things about being back in Australia is the availability of home visiting doctors.

It was actually faster and cheaper for me to get a home doctor out to look at me tonight than it was to get an appointment with my regular doctor. I wouldn't have gotten an appointment until some time tomorrow at the earliest (assuming he had appointments available), because I made the decision to see a doctor after 5pm, when they'd closed. Instead, I had a doctor at my door in a little more than 2 hours of making the request. It also worked out cheaper, because the home doctor bulk bills Medicare, whereas my regular doctor does not.

Add in the massive convenience of not having to lug a small child anywhere while I get seen by a doctor, and it's a major convenience. I love socialised healthcare.

It turned out I have an outer ear infection. So all we had to do after the doctor came was find a pharmacy that was still open after 7pm to get my ear drop prescription filled.

All of that mucking around meant that Zoe got to bed a little later than usual. It's another cool night tonight, so I'm hoping she'll sleep well and have another sleep in.

Tridge on UAVs: APM:Plane 3.0.0 released

Tue, 2014-04-08 11:14

The ardupilot development team is proud to announce the release of version 3.0.0 of APM:Plane. This is a major release with a lot of new features.

For each release I try to highlight the two or 3 key new features that have gone in since the last release. That is a more difficult task this time around because there are just so many new things. Still, I think the most important ones are the new Extended Kalman Filter (EKF) for attitude/position estimation, the extensive dual sensors support and the new AP_Mission library.

We have also managed to still keep support for the APM1 and APM2, although quite a few of the new features are not available on those boards. We don't yet know for how long we'll be able to keep going on supporting these old boards, so if you are thinking of getting a new board then you should get a Pixhawk, and if you want the best performance from the APM:Plane code then you should swap to a Pixhawk now. It really is a big improvement.

New Extended Kalman Filter

The biggest change for the 3.0.0 release (and in fact the major reason why we are calling it 3.0.0) is the new Extended Kalman Filter from Paul Riseborough. Using an EKF for attitude and position estimation was never an option on the APM2 as it didn't have the CPU power or memory to handle it. The Pixhawk does have plenty of floating point performance, and Paul has done a fantastic job of taking full advantage of the faster board.

As this is the first stable release with the EKF code we have decided to not enable it by default. It does however run all the time in parallel with the existing DCM code, and both attitude/position solutions are logged both to the on-board SD card and over MAVLink. You can enable the EKF code using the parameter AHRS_EKF_USE=1, which can be set and unset while flying, allowing you to experiment with using the EKF either by examining your logs with the EKF disabled to see how it would have done or by enabling it while flying.

The main thing you will notice with the EKF enabled is more accurate attitude estimation and better handling of sensor glitches. A Kalman filter has an internal estimate of the reliability of each of its sensor inputs, and is able to weight them accordingly. This means that if your accelerometers start giving data that is inconsistent with your other sensors then it can cope in a much more graceful way than our old DCM code.

The result is more accurate flying, particularly in turns. It also makes it possible to use higher tuning gains, as the increased accuracy of the attitude estimation means that you can push the airframe harder without it becoming unstable. You may find you can use a smaller value for NAVL1_PERIOD, giving tighter turns, and higher gains on your roll and pitch attitude controllers.

Paul has written up a more technical description of the new EKF code here:

http://plane.ardupilot.com/wiki/common-apm-navigation-extended-kalman-filter-overview/

Dual Sensors

The second really big change for this release is support for dual-sensors. We now take full advantage of the dual accelerometers and dual gyros in the Pixhawk, and can use dual-GPS for GPS failover. We already had dual compass support, so the only main sensors we don't support two of now are the barometer and the airspeed sensor. I fully expect we will support dual baro and dual airspeed in a future release.

You might wonder why dual sensors is useful, so let me give you an example. I fly a lot of nitro and petrol planes, and one of my planes (a BigStik 60) had a strange problem where it would be flying perfectly in AUTO mode, then when the throttle reached a very specific level the pitch solution would go crazy (sometimes off by 90 degrees). I managed to recover in MANUAL each time, but it certainly was exciting!

A careful analysis of the logs showed that the culprit was accelerometer aliasing. At a very specific throttle level the Z

accelerometer got a DC offset of 11 m/s/s. So when the plane was flying along nice and level the Z accelerometer would change from -10 m/s/s to +1 m/s/s. That resulted in massive errors in the attitude solution.

This sort of error happens because of the way the accelerometer is sampled. In the APM code the MPU6000 (used on both the APM2 and Pixhawk) samples the acceleration at 1kHz. So if you have a strong vibrational mode that is right on 1kHz then you are sampling the "top of the sine wave", and get a DC offset.

The normal way to fix this issue is to improve the physical anti-vibration mounting in the aircraft, but I don't like to fix

problems like this by making changes to my aircraft, as if I fix my aircraft it does nothing for the thousands of other people running the same code. As the lead APM developer I instead like to fix things in software, so that everyone benefits.

The solution was to take advantage of the fact that the Pixhawk has two accelerometers, one is a MPU6000, and the 2nd is a LSM303D. The LSM303D is sampled at 800Hz, whereas the MPU6000 is sampled at 1kHz. It would be extremely unusual to have a vibration mode with aliasing at both frequencies at once, which means that all we needed

to do was work out which accelerometer is accurate at any point in time. For the DCM code that involved matching each accelerometer at each time step to the combination of the GPS velocity vector and current attitude, and for the EKF it was a matter of producing a weighting for the two accelerometers based on the covariance matrix.

The result is that the plane flew perfectly with the new dual accelerometer code, automatically switching between accelerometers as aliasing occurred.

Since adding that code I have been on the lookout for signs of aliasing in other logs that people send me, and it looks like it is more common than we expected. It is rarely so dramatic as seen on my BigStik, but often results in some pitch error in turns. I am hopeful that with a Pixhawk and the 3.0 release of APM:Plane that these types of problems will now be greatly reduced.

For the dual gyro support we went with a much simpler solution and just average the two gyros when both are healthy. That reduces noise, and works well, but doesn't produce the dramatic improvements that the dual accelerometer code resulted in.

Dual GPS was also quite a large development effort. We now support connecting a 2nd GPS to the serial4/5 port on the Pixhawk. This allows you to protect against GPS glitches, and has also allowed us to get a lot of logs showing that even with two identical GPS modules it is quite common for one of the GPS modules to get a significant error

during a flight. The new code currently switches between the two GPS modules based on the lock status and number of satellites, but we are working on a more sophisticated switching mechanism.

Supporting dual GPS has also made it easier to test new GPS modules. This has enabled us to do more direct comparisons between the Lea6 and the Neo7 for example, and found the Neo7 performs very well. It also helps with developing completely new GPS drivers, such as the Piksi driver (see notes below).

New AP_Mission library

Many months ago Brandon Jones re-worked our mission handling code to be a library, making it much cleaner and fixing a number of long term annoyances with the behaviour. For this release Randy built upon the work that Brandon did and created the new AP_Mission library.

The main feature of this library from the point of view of the developers is that it has a much cleaner interface, but it also has some new user-visible features. The one that many users will be glad to hear is that it no longer needs a "dummy waypoint" after a jump. That was always an annoyance when creating complex missions.

The real advantage of AP_Mission will come in future releases though, as it has the ability to look ahead in the mission to see what is coming, allowing for more sophisticated navigation. The copter code already takes advantage of this with the new spline waypoint feature, and we expect to take similar advantage of this in APM:Plane in future releases.

New Piksi GPS driver

One of the most exciting things to happen in the world of GPS modules in the last couple of years is the announcement by SwiftNav that they would be producing a RTK capable GPS module called the Piksi at a price that (while certainly expensive!) is within reach of more dedicated hobbyists. It offers the possibility of decimeter and possibly even centimetre level relative positioning, which has a lot of potential for small aircraft, particularly for landing control and more precise aerial mapping.

This release of APM:Plane has the first driver for the Piksi. The new driver is written by Niels Joubert, and he has done a great job. It is only a start though, as this is a single point positioning driver. It will allow you to use your new Piksi if you were part of the kickstarter, but it doesn't yet let you use it in RTK mode. Niels and the SwiftNav team are working on a full RTK driver which we hope will be in the next release.

Support for more RC channels

This release is the first to allow use of more than 8 RC input channels. We now support up to 18 input channels on  SBus on Pixhawk, with up to 14 of them able to be assigned to functions using the RCn_FUNCTION settings. For my own flying I now use a FrSky Taranis with X8R and X6R receivers and they work very nicely. Many thanks to the PX4 team, and especially to Holger and Lorenz for their great work on improving the SBus code.

Flaperon Support

This release is the first to have integrated flaperon support, and also includes much improved flaps support in general. You can now set a FLAP_IN_CHANNEL parameter to give an RC channel for manual flap control, and setup a  FLAPERON_OUTPUT to allow you to setup your ailerons for both manual and automatic flaperon control.

We don't yet have a full wiki page on setting up flaperons, but you can read about the parameters here:

http://plane.ardupilot.com/wiki/arduplane-parameters/#Flap_input_channel_ArduPlaneFLAP_IN_CHANNEL

Geofence improvements

Michael Day has made an number of significant improvements to the geo-fencing support for this release. It is now possible to enable/disable the geofence via MAVLink, allowing ground stations to control the fence.

There are also three new fence control parameters. One is FENCE_RET_RALLY which when enabled tells APM to fly back to the closest rally point on a fence breach, instead of flying to the centre of the fence area. That can be very useful for more precise control of fence breach handling.

The second new parameter is FENCE_AUTOENABLE, which allows you to automatically enable a geofence on takeoff, and disable when doing an automatic landing. That is very useful for fully automated missions.

The third new geofence parameter is FENCE_RETALT, which allows you to specify a return altitude on fence breach. This can be used to override the default (half way between min and max fence altitude).

Automatic Landing improvements

Michael has also been busy on the automatic landing code, with improvements to the TECS speed/height control when landing and new TECS_LAND_ARSPD and TECS_LAND_THR parameters to control airspeed and throttle when landing. This is much simpler to setup than DO_CHANGE_SPEED commands in a mission.

Michael is also working on automatic path planning for landing, based on the rally points code. We hope that will get into a release soon.

Detailed Pixhawk Power Logging

One of the most common causes of issues with autopilots is power handling, with poor power supplies leading to brownouts or sensor malfunction. For this release we have enabled detailed logging of the information available from the on-board power management system of the Pixhawk, allowing us to log the status of 3 different power sources (brick input, servo rail and USB) and log the voltage level of the servo rail separately from the 5v peripheral rail on the FMU.

This new logging should make it much easier for us to diagnose power issues that users may run into.

New SERIAL_CONTROL protocol

This release adds a new SERIAL_CONTROL MAVLink message which makes it possible to remotely control a serial port on a Pixhawk from a ground station. This makes it possible to do things like upgrade the firmware on a 3DR radio without removing it from an aircraft, and will also make it possible to attach to and control a GPS without removing it from the plane.

There is still work to be done in the ground station code to take full advantage of this new feature and we hope to provide documentation soon on how to use u-Blox uCenter to talk to and configure a GPS in an aircraft and to offer an easy 3DR radio upgrade button via the Pixhawk USB port.

Lots of other changes!

There have been a lot of other improvements in the code, but to stop this turning into a book instead of a set of release notes I'll stop the detailed description there. Instead here is a list of the more important changes not mentioned above:

  • added LOG_WHEN_DISARMED flag in LOG_BITMASK
  • raised default LIM_PITCH_MAX to 20 degrees
  • support a separate steering channel from the rudder channel
  • faster mission upload on USB
  • new mavlink API for reduced memory usage
  • fixes for the APM_OBC Outback Challenge module
  • fixed accelerometer launch detection with no airspeed sensor
  • greatly improved UART flow control on Pixhawk
  • added BRD_SAFETYENABLE option to auto-enable the safety switch on PX4 and Pixhawk on boot
  • fixed pitot tube ordering bug and added ARSPD_TUBE_ORDER parameter
  • fixed log corruption bug on PX4 and Pixhawk
  • fixed repeated log download bug on PX4 and Pixhawk
  • new Replay tool for detailed log replay and analysis
  • flymaple updates from Mike McCauley
  • fixed zero logs display in MAVLink log download
  • fixed norm_input for cruise mode attitude control
  • added RADIO_STATUS logging in aircraft logs
  • added UBX monitor messages for detailed hardware logging of u-Blox status
  • added MS4525 I2C airspeed sensor voltage compensation

I hope that everyone enjoys flying this new APM:Plane release as much as we enjoyed producing it! It is a major milestone in the development of the fixed wing code for APM, and I think puts us in a great position for future development.

Happy flying!