Forum Discussion
tomma
Nimbostratus
NimbostratusInquiry on F5's Maintenance Mode Feature for Pool Members
Hello F5 Community, I'm looking for a way to smoothly transition specific pool members into maintenance mode without disrupting service. Can anyone share insights or best practices on how to impleme...
Both "disable" and "force offline" actions may answer the requirement as they both provide some level of smoothness
- When set to Disabled, a node or pool member continues to process persistent and active connections. It can accept new connections only if the connections belong to an existing persistence session.
- When set to Forced Offline, a node or pool member allows existing connections to time out, but no new connections are allowed
So, for the first you need to disable the node then wait for a sufficient time to make sure there is no active nor persistent connection related to that node. Typically, you will disable a node 30 minutes to a few hours before the maintenance schedule.
For the second, you set the node to forced offline and wait a few minutes until there is no active connection to this node. Note that persistence here is immediately lost and any client who is in the persistence table but who is not actively connected will load blance to the next member.
Amine_Kadimi
MVP
MVPBoth "disable" and "force offline" actions may answer the requirement as they both provide some level of smoothness
- When set to Disabled, a node or pool member continues to process persistent and active connections. It can accept new connections only if the connections belong to an existing persistence session.
- When set to Forced Offline, a node or pool member allows existing connections to time out, but no new connections are allowed
So, for the first you need to disable the node then wait for a sufficient time to make sure there is no active nor persistent connection related to that node. Typically, you will disable a node 30 minutes to a few hours before the maintenance schedule.
For the second, you set the node to forced offline and wait a few minutes until there is no active connection to this node. Note that persistence here is immediately lost and any client who is in the persistence table but who is not actively connected will load blance to the next member.
tommaNimbostratus
NimbostratusSo you're telling me that there is no other way than just to "force offline" a pool member and wait till all the old connections are no longer active? I was hoping there could be a way to move active connections to another pool member...
- P_Kueppers
You can kill those connections from CLI after you force offline it:
"tmsh delete /sys connection ss-server-addr 1.1.1.1"
where 1.1.1.1 is your poolmember
- tomma
Killing active connection would lead to interrupts in our service. I was talking about moving established connections to second pool member, but I guess F5 does not have a feature like that.
gersbahCirrostratus
Do your pool members share a connection table and/or application state? Or are you using a stateless protocol? Otherwise how would the second pool member know what to do with this already established connection that was just moved over?
If you are using UDP, you could look into datagram LB to force individual packet load balancing instead of virtual "UDP connections".
Other than that, yes, setting a member to forced offline and waiting for connections to time out is the smoothest transition you can hope for.
- Amine_Kadimi
Can you clarify your requirements? what do you mean by smoothly transitioning into maintenance mode, and what do you want to exactly achieve? If you don't want to affect end user experience, then depending on your application logic you may have to use either disable member or force offline, the first is less aggressive cause it will also wait for persistent sessions to expire, if persistence is not an issue for you then I don't see why "force offline" would be a problem
