SysDig for Docker & Kubernetes

28 Jan

The first thing the name “Sysdig” reminded me of was that of ht://Dig, for those of us who ever needed to implement some full text search on their website two decades ago, ht://Dig was the way to go. Now I am not sure if Sysdig guys had any inspiration from ht://Dig for the name, but I am sure it’s got some very interesting features that may well cause it to become something of a first choice for monitoring your containers.

So about a month ago, we had a demo by the SysDig guys over a conference call and I must say that I was impressed by the level of detail captured by this new monitoring solution. To sum it up in one line, it captures the type of system calls done by Docker containers (and hence your apps running in them) and Kubernetes clusters if you think on a broader scale: and lets you know precisely when things deviate from the learned or expected norms. I plan to run an evaluation soon and will share further experiences.

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Memcached plugin with XTRADB Cluster / Galera

23 Mar

Having used memcached plugin for InnoDB in single node installations in the past with satisfacroty results, I wondered if it was possible to create a clustered setup which allows better scaling and provided replication of keys & values from one Memcached to another one, thus allowing more concurrent reads and prevention of the cold cache problem in the event of a restart that’s usual in a sharded cluster. I have been using Couchbase for a while with great results, but wanted to find something that could be made available to legacy applications for instance running versions of PHP that can’t do a native Couchbase client. (No doubt Couchbase does Memcache, but still wanted to check if Galera was up to the task) So I was wondering if it is possible to put something together using XTRADB Cluster / Galera as a back end for Memcached. I found some documentation that explained how to setup such an arrangement for NDB cluster but that makes use of a special memcached plugin for NDB. Couldn’t find a mention of the InnoDB Memached plugin being usable with Galera / XTRADB anywhere, so I decided to try it out myself.

I started up my dev cluster and setup the innodb memcached plugin using the script included with the XTRADB cluster. This creates a InnoDB Memcache config database and creates a test mapping to a table in the test schema called demo_test.


So, the above script caused the database and mapping to be created on all three XTRADB nodes I had in the cluster. I tested a few reads of the test data from all the nodes using memcached port 11211 and they all seemed to respond fairly well. So, I decided to send some SET requests and check if those replicate. So, I ran a SET operation on one of the nodes and the demo_test table got the data, but to my disappointment the other nodes didn’t get it. It appeared as if the Galera layer didn’t know that Memcached plugin had inserted some data into InnoDB. I remembered that there is a variable  innodb_api_enable_binlog that controls if the Memcached updates will be written to MySQL Binary log, that defaults to off and I didn’t change it to on.

So, i changed the value of that variable to on, restarted the cluster to make the value effective. Tested reads with memcached and they were fine. Then I ran some writes through memcached and it was still the same. So, I concluded that memcached plugin writing to InnoDB goes unnoticed by the Galera library. I’ll dig into the code to see why that doesn’t work. I wonder if anyone else has had the same experience?

I also intend to upgrade my cluster to a newer version and repeat the tests. I am currently testing on XTRADB cluster 5.6.25 on CentOS 6.7 32 -bit.


Couchbase server 3 Beta 2

22 Sep

I have been eagerly looking forward to Couchbase server version 3’s final edition to come out. Looks like we just came a bit closer to that as Couchbase have announced beta 2 for version 3. I am going to give it a go.

Please use the link below to download and test it out.

Download Couchbase version 3 Beta 2


Watch “Mod-09 Lec-02 MOSFET : Device Structures and Char…” on YouTube

04 Sep

Mod-09 Lec-02 MOSFET : Device Structures and Char…:


Watch “Logstash Presentation” on YouTube

13 Jul

Logstash Presentation:


cNet Top 5 : Best features in Apple iOS 8

25 Jun

Donald Bell explains the best features in upcoming iOS8. The better keyboard is something that might make me think about considering an iPhone for my next phone upgrade 🙂

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Posted in iOS, OS


Android Headlines: Designer Google Glass Frames And Shades From Diane Von Furstenberg Now Available

24 Jun

Android Headlines: Designer Google Glass Frames And Shades From Diane Von Furstenberg Now Available.


Google Glass on sale in the UK for £1,000

24 Jun

The Guardian: Google Glass on sale in the UK for £1,000.


Watch “Introduction to Docker” on YouTube

23 Jun

Introduction to Docker:


Introduction to Angular.js in 50 Examples (part 1)

20 Jun

Quite an enjoyable video, one of the best introductions to Angular.JS

Introduction to Angular.js in 50 Examples (part 1):