Running PVCS and SLM in high availability

Question

Hi 
 We are planning to move our current PVCS (and SLM) install to new servers (RHEL 8) 
 We we are planning to have two servers which will both contain PVCS VM and SLM 
 The idea is to have active/passive high availability where one server will have the processes started (PVCS + SLM) while the other remains in standby 
 These two servers have a shared NFS filesystem where the PVCS projects will be stored 
 Projects will be accessed by clients via PVCS Fileserver 
 
 My question is regarding license rehosting/activation in this scenario: 
 How should we calculate the hostid for the license to be valid in both servers? 
 thanks!

Richard Gering · Answer

Hi Pedro, 
 SLM only supports high availability using a 3-server configuration, also known as a license triad. For details, see the following KB doc: 
 https://knowledgebase.serena.com/InfoCenter/index?page=content&id=S129439 
 For this to work you would need a 3rd machine, and this machine cannot go down if one of the active/passive machine is not operational, given 2 of the 3 machines need to be up. It is typically easier to pick 3 always-on servers, unrelated to any active/passive HA configuration, where one of those machines is allowed to go down. 
 For a 2-server configuration your choices are: 
 
 Split licenses between servers. Expensive if half of those licenses cannot be used because the machine is off during the passive phase. Doable if both machines remain operational, with clients pointing to both servers, each supporting 50% of the users. You would lose 50% capacity at the time of a failure, though. 
 Do not install licenses on passive HA machine, and only put those in place during a failure. At that point you would rehost your license, making all of them available on the previously passive machine. No loss of capacity, but not a fully automatic fail-over. 
 A combination of the previous two, where the 50% loss in capacity is solved post fail-over by rehosting the licenses assigned to the server that went offline to the then active server. 
 
 For future planning: the next PVCS VM release will use the AutoPass License Server (APLS), which does support 2-server High Availability using an external Postgres, Oracle, or MS SQL database . 
 Kind regards, 
 - Richard.

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Running PVCS and SLM in high availability

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