Uptime is a slippery thing… If you want to calculate the availability of a service then it is simply amount of time service is available ———————————– x 100 amount of time that has passed If you have a cluster providing the service, then the likelyhood that the service becomes unavailable does down but the availability … Read more
We recently started researching GlusterFS for our own usage so this question was interesting to me. Gluster uses what are called ‘translators’ on the FUSE client to handle how you store data. There are several types of translators which are outlined here: http://www.gluster.com/community/documentation/index.php/GlusterFS_Translators_v1.3 The one you are asking about specifically is called the Automatic File … Read more
This is a slightly older question but the problem presented here is based on a misconception on how and when failover in clusters, especially two-node clusters, works. The gist is: You can not do failover testing by disabling communication between the two nodes. Doing so will result in exactly what you are seeing, a split-brain … Read more
Since it is writing to disk via binlog, I’d think you could do something similar to what MySQL admins typically do: heartbeat w/ DRBD (example here). The last time I tried to use heartbeat though, it didn’t support non-multicast checking between nodes, meaning that it was more or less impossible to run on cloud/VPS infrastructure … Read more
Sounds like you may be looking for a Global Server Load Balancing (GSLB) solution. GSLB usually uses “smart” DNS to direct users to different servers based on a number of parameters (i.e. server unavailable, high load, ip geolocation, etc). As an example, say you have two web servers, one out west (10.10.10.1/24) and one east … Read more
Believe the question has been very precisely answered by Willy Tarreau, the author of HAProxy, in http://www.formilux.org/archives/haproxy/1003/3259.html. Citation from the above link Heartbeat is not the best tool to get a redundant haproxy setup, it was designed to build clusters, which is a lot different from having two redundant stateless network equipments. Network oriented tools … Read more