Monday, June 1, 2015

CDOT Tip #2

Here’s a nugget that is relevant to anyone who does CDOT implementations and surprised me when I found it out last year.  Essentially, cluster ha modify should only be run on 2 node clusters, because cluster ha (high availability) is different than storage failover.

Storage failover modify –mode non-ha: This is for Single Node Clusters.
Cluster ha modify –configured true: This is for Two Node Clusters only.  This disables Epsilon (the system of tie-breaking for 4+ node clusters). 
Storage failover modify –mode ha: This controls what we normally understand as takeover/giveback (cf enable).  It is applicable for any 2+ node cluster.  This  must be configured correctly for “cluster ha modify” to work. 

Lastly, if you have a 2-node cluster and you have set cluster ha modify to true, you will need to manually set it to false when you add nodes to grow the cluster.

Bonus link: Here is a description of which ONTAP files (q, e, I, m) are compatible with each platform.  In general, the ‘q’ file is what you will use, in the form “814P1_q_image.tgz.”  The .zip is the older format, for use with upgrades from 7.x systems, while the .tgz is used for upgrades from 8.x systems.  Lastly, netboot is for booting systems from an image on your laptop/server. 

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