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How Many Front-End servers can I reboot – “Pool” Quorum?

How Many Front-End servers can I reboot – “Pool” Quorum?

With the presence of Windows fabric used in Skype for Business server 2015 in relation to pool quorum and the existence of routing group quorums, we have to be careful about how many Front-End servers are rebooted at the same time as to not affect the quorum on any of them. Here we’ll take a look at both Pool and Routing Group quorum and areas to take into consideration when reboots are requested or required.

Pool Quorum

This area is straight forward with the manner of servers that you can reboot and not lose quorum. We can see in figure 1 below that as long as we have “more” than the majority of the servers in the pool up and running then its fine for us to reboot.

Note: You define “up and running” by having all the Skype services running, to be more specific the RTCsrv service needs to be running on the Front – End Server.

Fig 1: Pool Quorum to be established at start up.

Total number of servers in the pool Number of servers that must be running for the pool to be started the first time
2 1
3 3
4 3
5 4
6 5
7 5
8 6
9 7
10 8
11 9
12 10

 

 

Fig 2: Pool Quorum to be maintained once the pool is operational

Total number of servers in the pool Number of servers that must be running for the pool to remain with pool quorum
2 (Do not advise to have just two servers in the Front-End Pool) 1
3 2
4 2 (As long as SQL Mirror is on the primary)
5 3
6 3 (As long as SQL Mirror is on the primary)
7 4
8 4 (As long as SQL Mirror is on the primary)
9 5
10 5 (As long as SQL Mirror is on the primary)
11 6
12 6 (As long as SQL Mirror is on the primary)

 

 

So, for the sake of arguments I will illustrate one more example of how this would look with the answer of Yes or No,  if should do a reboot on a particular pool.

Note: This is to protect pool quorum and not routing group quorum; Each bold item represents that server being rebooted out of the pool.

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = Yes

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = Yes

FE 1 | FE 2 | F 3 | F4 | F5 | F6 | F7 | F8 = Yes

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = Yes (As long as SQL Mirror is on the primary)

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = No

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = No

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = No

FE 1 | FE 2 | F3 | F4 | F5 | F6 | F7 | F8 = No

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