Essential software part 1 Browsers

Browsers

Your browser is your portal to the internet and it is an emotive subject for some the choice of which to use. Some applications work better with some browsers than other browsers then there are some legacy applications that only work with old versions of Internet Explorer. In my professional opinion and my experience you should use something new and keep it updated.

On my computer at work I keep the following browsers installed

Why upgrade

Note If you are running Windows XP or older I would strongly recommend you to install Chrome or Firefox and update Explorer to the latest that you can. Earlier versions of Explorer are buggy and exploitable by criminals. Please note all browsers have weaknesses and exploits are found regularly in all of them but old versions of Internet Explorer are the biggest target.

Then there are positive reasons to change browser

Chrome

The auto updater works well and in the background keeping your install of chrome up to date without the hastle. Mos the other others are following suit and implimenting their own updates.

Google services integrate well into Chrome indcluding the excellent bookmarks sync and the tab sync between devices. See this page for more info.

Hidden hint – For an advanced look at a page composition hold down the ctl shift and I keys then reload a page for some really cool info.

Firefox

Well known and mature. Firefox has been about for over a decade and has come along way. The length of time that firefox has been about means that it has had the most exposure to web developers other than Internet Explorer. The add ons for firefox are a huge asset and I know many web developers who swear by Firebug add on.

The new tabbing system in Firefox is pretty awesome too.
Hidden hint – In the URL bar enter about:config to get into the hidden configuration options for your browser. Be careful though you can break things.

Opera

A  secure browser which is pretty easy to use and has a big following of devoted supporters. Opera have been about for a long time and they are the most prevelent mobile browser in the world. I like the way the tabs work and I think it is second in performance only to chrome.
Hidden hint – Type /. in the URL bar to short cut direct to slashdot.com

Internet Explorer

Most people use it by default. It does have some great integration into modern graphics hardware if you find a site that needs it. And it is installed by default on all windows machines (except N versions). Looks pretty when the Areo theme is running.
Hidden hint – ? If you know one let me know ?

Everybody out!

The mars rover started me (as I am certain it did for many people) thinking about the universe.

Then I came across a funny article on XKCD what if called Everybody Out which is part of the new What If collection from Randle Munroe which throws in a bit of humor while trying to answer pretty silly questions such as “Is there enough energy to move the entire current human population off-planet?”

I wont spoil the answer…..

Cassandra cluster

It’s live and it’s quick!

I helped to implement a Cassandra cluster inside an Amazon VPC earlier this year. It worked fine if a bit slow. We tried increasing the number of nodes (Scale out) and we tried larger nodes (Scale up) along with tuning Cassandra and the application. In the end we could make the application go a bit faster but the connection to the Cassandra cluster seemed to be the limiting factor. The decision was made for speed reasons to get the Cassandra nodes into our rack so that we had a fast link between the application server and the Cassandra Cluster.

We had loads of fun testing configuration options to get a well balanced specification of server while fitting inside the power and financial budget.

We had a specialist from Acunu for a quick training session with us to ensure we have a good grasp of the pretty specialist requirements of Cassandra; its tuning; Maintenance and the underlying technology. This helped us to come to understand the magic triad that needs to be balanced to run a node effectively.

The Triad of per node balance.

Memory – Minimum of 8GB of RAM, 4GB for Java heap and 4 GB of Cache. The Maximum (not a hard limit as you will see) is 16GB of RAM, 8GB for the Java heap and 8GB for the Cache. The Maximum is 16GB because if the heap is too large then the full Java Garbage Collection which pauses the all process will take too long and the node will fall out of the cluster. In our experience a Dual socket Quad core system (8 Hardware threads) can pause for upwards of 10 seconds in a production machine doing a full garbage collection of 8GB of RAM.

Processor – Quad core is a minimum. It mainly effects the garbage collection and SSTables compaction times but these are what will cause your cluster to do funny things like drop a node for a few minutes.

Disk – Disks are a must not SSD’s. Under the hood Cassandra does all of its writing to disk in a serial fashion which is optimized for traditional spinning media. The commit log should have its own disk as it is effectively being written to continuously and this is why an SSD will not last long. The data disk needs high throughput as well as fast access this will allow the Memtables to be flushed to disk as quickly as possible reducing the impact on other actions.

In the end we bought systems with the following specs

  •  1 * 6 core (12 including hyper threadding) Xeon processor running at 2.0 Ghz
  • 16GB of Ram (Quad channel DDR3)
  • 1 OS disk 7,200 RPM
  • 1 Commit log 10,000 RPM disk
  • 3 Data disks in a hardware stripe 10,000 RPM disks

Each node runs at less than 300watts peak and Cassandra shows an avg write latency of 2.2ms!

The performance increase of moving the cluster closer to the application has been huge. One report that would take a minute upwards in AWS (Returning a couple of hundred megabytes of data) now runs in under 10 seconds when the Cassandra system is cold and under 2 when the Cassandra cluster has had time to warm up the Cache.

The one thing that is most important to remember with Cassandra is that Cassandra is a write bias data store. This means that Writes are very fast, generally faster than retrieval so you have to think differently when writing an application that uses Cassandra. It is better to write a new value that overwrites an old one than it is to load an old value then update it with the new value. Get the data model right and the use case for Cassandra will guide you to a new world of highly available fast data storage. If your workload is read biased then Cassandra may not be for you.

 

Deneb rebranding

Hi All,

After a hiatus in the Deneb website I have found the time to reboot Deneb and re-brand the website.

Previously Deneb was focused on selling products and services through the traditional sales pattern of pitching what Deneb can offer your business; However I have been working for a new company that has helped me to understand the power of social networking and newer technologies and techniques.

To that end here is the new Deneb site, a blog that will be a home for all the new information that I have gathered and a place to show you all how great Deneb is!

Enjoy; Regards Sam