Percona Clustercheck Improved Error Handling Patch

Here’s my Github pull request for improved error handling in Percona’s clustercheck utility, used by haproxy for health-checking a Percona XtraDB Cluster.

It adds two features:

  1. 401 Unauthorized response for failed authentication
  2. 404 Not Found response if the mysql program can’t be found

The error detection is done in a low-latency manner using PIPESTATUS, without an additional database connection. Here is colored diff output.

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Lessons from “Gear-Up Mishap Was Botched Go-Around”

Hitting the runway on a go-around is not the greatest airmanship, but the Aerostar pilot did one thing right: he didn’t panic and continued flying the airplane.

Aerostar with curled props after ground contact.

It is interesting to see that a plane can fly 80 miles with both prop tips curled back 6″, but then it was a light load.

Most pilots would argue that he should have returned for landing despite not having on-airport repair facilities, but crating the plane up and shipping it back home becomes a pressing factor when you’re the owner.

(When I did my commercial training in Florida, the owner specifically requested that instructors and renters return home for repairs instead of landing at nearby Cape Canaveral, which had a much longer runway. We ignored him, as a matter of safety, of course, but we weren’t paying for potential crating/shipping of broken airplanes.)

“Q-tip” prop design increases efficiency with less span-wise airflow (“air fence”) and reduces noise (smaller blade diameter means lower tip velocity, which approaches speed of sound.) It also increases ground clearance. :) Gear-Up Mishap Was Botched Go-Around When An Airplane Has A Q-Tip Propeller
W: Propeller

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GNU Parted Alignment Check Option

GNU Parted 2.1 (available in Redhat 6+) has a very interesting option for storage engineers, sysadmins and DBAs:

2.4.1 align-check

Command: align-check align-type n

    Determine whether the starting sector of partition n meets the
disk’s selected alignment criteria. align-type must be ‘minimal’,
‘optimal’ or an abbreviation. When in script mode, if the partition
does not meet the alignment requirement, exit with status 1;
otherwise (including on older kernels for which alignment data
is not available), continue processing any remaining commands.
Without --script, print either ‘N aligned’ or ‘N not aligned’.


    (parted) align-check minimal 1
    1 aligned


Script to automatically partition a new disk and create LVM PV

1) fdisk can be used in scripts. people do that every day.
2) parted -a just reports if alignment is optimal, it doesn't align.
So you need a loop or something to attempt an optimal alignment.

Create partition aligned using parted

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O’Reilly: Managing Mission-Critical Domains and DNS

It’s been a while since I looked forward to a book, but this one by Mark Jeftovic of looks pretty interesting:

What’s amusing is that Amazon lists it as #1 in “Hot New Releases in Unix DNS & Bind.” Unsurprisingly, it’s also the only title in that category. :) Managing Mission-Critical Domains and DNS Managing Mission-Critical Domains and DNS

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Drones and ADS-B

DJI Phantom Drone

AvWeb has a very interesting article on possible Google involvement with drones and ADS-B.

For those new to ADS-B, at a high level it is digital beacon that must be installed on all airliners world-wide, and in the USA all airplanes by 2020. The cost is borne by the airplane operator, and ranges from $5,000 for a small plane to $1 million or more for an airliner, including avionics and installation costs.

“ADS-B out” is the digital transmitter, and “ADS-B in” is the digital reception of weather and ATC data.

Since $5,000+ is a lot of money for something that doesn’t make you fly better, if the FAA decides to impose ADS-B on drones, then a big outside player like Google or Amazon will have to design/manufacture low cost versions to make drones cost-effective. Like an order of magnitude cheaper, or even two.

One of the commenters has an interesting question, “Just how many airborne ADS-B devices can the FAA’s ground-bound infrastructure handle at one time? The answer to that question may frame the response that we can expect from the agency… Seriously.”

FAA allows AIG to use drones for insurance inspections
DJI: A Chinese firm has taken the lead in commercial drones

wikipedia: Traffic collision avoidance system

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