It would appear that the release of Coolstack 1.3.1 was a little more adventurous than previous versions, as the following timeline illustrates.
10 June 2008
Firstly, we had the launch of Coolstack 1.3 Release Candidate 1 which seemed to work fine on my 10u3 systems but was still technically only a candidate release.
11 July 2008
Then, around 4 weeks later, the official version of Coolstack 1.3 was released. This included a number of minor software revision enhancements but more importantly, included the addition of DTrace probes in applications such as MySQL, Ruby and Memcached. However, the addition of these probes required either the use of Solaris 10 U5 or the installation of a number of Solaris kernel patches, neither of which went down too well in the Coolstack community. As a result, this version 1.3 was withdrawn and 1.3RC1 became the official 1.3 release.
14 August 2008
In an effort to support Solaris versions prior to U5, the DTrace probes were backed out of the affected applications and Coolstack 1.3.1 was born. A number of other minor software enhancements were also added but in essence, 1.3.1 was all about satisfying the wider Coolstack community.
I did eventually get the opportunity to try out Coolstack 1.3.1 and did not encounter any major issues. We are planning a more comprehensive review of the reported MySQL performance gains though.