primary-secondary in an iRule

Priority works unless you really truly need traffic to go to only 1 pool member. With just priority, and with persistence of any kind enabled, when the higher prio nodes come back up after failing, you will see traffic distributed across multiple pool members until old connections/sessions die off.

Here's a really slick way to stick to one and only one server in a pool.

Apply to the VS a universal persistence profile using an iRule like this:

rule PriorityFailover {
  when CLIENT_ACCEPTED { persist uie 1 }
}

The first connection will create a single universal persistence record with a key of "1". All subsequent connections will look up persistence using "1" as the key, resulting in truly universal persistence for all connections. (Use 1 or any constant value. 0 will have the same affect as using 1. One of my customers uses "persist uie [TCP::local_port]"

When one node fails, the other is persisted to by all comers. When the 2nd node fails, the 1st again becomes the preferred node for all, ad infinitum.

Doesn't offer the capability of manual resume after failure, or true designation of a "primary" and "secondary" instance (sometimes required for db applications), but it sure does solve the problem of "only use one node at a time, I don't care which one, please" (You can use priority to gravitate towards the top of a list...)

HTH

/deb