Blog Planet

We don’t yet officially support running the KnowledgeTree server on Macs due to complications around getting all of KnowledgeTree’s dependancies working on OS X. In particular, OpenOffice.org’s dependancy on X11 (and not native Aqua) makes putting together an easy to install, commercially supported stack quite complicated. (A native Aqua port of OpenOffice.org is ostensibly on the way but there hasn’t been a development release since July 2007 )-: ) 

There are however two routes to getting the KnowledgeTree server working on the Mac:

•  installing from source code: installing and enabling Apache, PHP5, MySQL, Java, X11 and OpenOffice for your Mac and then following the KnowledgeTree “Source Only” install instructions (this is the harder install route);
• using BitRock’s very cool BitNami stack for KnowledgeTree, an easy to use “one-click” install of KnowledgeTree (and most of its dependencies) for a variety of platform’s, including the Mac (this is the easy way to install KnowledgeTree).

The BitNami KnowledgeTree stack is currently based on KnowledgeTree 3.5.2 Beta 1 but should be updated to a newer version sometime in the near future. Whilst this is a really slick and easy way to install most of KnowledgeTree’s dependancies BitNami still doesn’t ship with Java (J2SE), the Lucene Indexer enabled and OpenOffice installed. As a result, you will still need to follow the Source Only instructions mentioned above (and tailor appropriately for Mac OS X) to get document full-text indexing and KnowledgeTree’s powerful search capabilities working properly across document contents (metadata should still be indexed as it is database-bound).  

BitRock, the guys who provide KnowledgeTree’s certified stack technology, have also added a number of other stacks to their BitNami portal, covering popular CMS’s, blog applications, bug trackers and the like. Well worth a look.

BitNami’s KnowledgeTree installer running on OS X 10.5.2 Leopard:

And the welcome page (note that BitNami’s Apache runs on port 8080 to avoid conflict with OS X’s own Apache instance):

As mentioned above, the BitNami installer doesn’t install all dependancies and KnowledgeTree notifies you of this on the Administrator’s dashboard:

  And the BitNami stack’s PHP Info: 

Amazon’s Simple Storage Service (S3) experienced an outage earlier today, which affected KnowledgeTreeLive and its users. The outage was quite widely reported. 

KnowledgeTreeLive is in beta and so this was a great way to learn about our contingency planning, both from a technology perspective but also process and communication.

The pundits appear to be pointing to major holes in the cloud computing model which I think is somewhat exaggerating the impact and significance of today. All systems have issues, and this is not entirely unexpected. To provide some context here, we recently experienced outages with our (expensive) hosting provider, RackSpace, who are supposed to be best in the business (and we were by no means the only parties affected). Amazon has had a really great track-record of keeping S3 up and running for the last few years (over 99.993% of the time) and one or two small, isolated outages are acceptable and indeed, expected.

There are however some learnings suggested by others that I do hope Amazon will take to heart.

This is all well and good but it is up to us companies who leverage cloud computing technologies to provide our customers with a innovative (and reasonably priced) services, to ensure that we engineer our systems appropriately to gracefully deal with these situations.

  What this outage meant for KnowledgeTreeLive users

• During the period of the outage, all documents stored in Amazon S3 were safe and unaffected.
• We experienced problems with the creation of new KnowledgeTreeLive accounts, particularly if you asked for demo data to be placed into your repository. Our support guys picked up on these pretty quickly and contacted the users affected by this.
• Users weren’t able to upload new documents, not a great state but what we think is an appropriate behavior - we want users to be certain that their documents are stored safely in persistent storage.
• Users weren’t able to download documents they had previously stored. This is certainly not an ideal situation and we’ll be investigating how we can implement a cache of documents within our cluster, probably utilizing the distributed filesystem between the various front-end web server appliances.
• We couldn’t start up new Amazon Elastic Compute Cloud AMI’s and if we needed to due to a significant increase in load we would have had to take the entire system into maintenance mode. Maintenance Mode and other fail-safes are managed from outside of the Amazon cloud.

Some learnings for KnowledgeTreeLive 

• We need to investigate a “Hot Cache” for documents uploaded to KnowledgeTreeLive, most likely leveraging a distributed filesystem running between our web server appliances. This will allow our customers to continue to have access to their documents during an S3 outage.
• We need to be better at keeping users informed about what’s going on. We have a KnowledgeTreeLive Beta blog and send an RSS feed of the blog to the KnowledgeTreeLive dashboard, but didn’t do it fast enough this time around.

We’re meeting early this coming week to discuss how we can plug these technology and process holes and I’m likely to blog about the outcomes.

Earlier today we experienced intermittent failures reading from, and writing to, the Amazon Simple Storage Service. This would have affected some account creations and the reading of writing of documents to KnowledgeTreeLive. KnowledgeTreeLive does attempt to retry writes to the S3 repository and, if it fails, will notify the user of the failed upload of a document.

It is understood that Amazon has resolved the issue and service has stabilized.

We appear to have sorted out our JIRA issue tracker for now. We are encountering issues with it periodically and hope to have a more permanent fix in place soon.

We’re having intermittent issues communicating with our ticketing system from within KnowledgeTreeLive. This will only affect access to the ticketing system for bug reporting.

We’re working on the problem and hope to resolve it shortly.