Replacing stack cable live

[CSCO12063651]

Hi,

I have two 3750X switches in a stack. There are two stack cables used for redundancy.

Recently one of the stack connections has become unreliable (see output below) and I want to rule out a faulty cable by changing it. My question is can one of the cables be swapped live without causing any issues to the running switches? I am not sure if when plugging in the replacement cable it will cause any interruption. Is it best practice to power off in this situation? All the info I can find relates to removing or introducing another switch to the stack, but not just changing a redundant cable.

Logs showing faulty connection:

Sep 18 05:32:43.057 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
Sep 18 10:13:38.291 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
Sep 18 10:13:39.297 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
Sep 18 11:43:36.645 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
Sep 18 11:43:36.763 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 2 has changed to state DOWN
Sep 18 11:43:37.652 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state UP
Sep 18 11:43:37.761 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 2 has changed to state UP
Sep 18 11:47:46.417 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 2 Switch 1 has changed to state DOWN
Sep 18 11:47:46.702 BST: %STACKMGR-4-STACK_LINK_CHANGE: Stack Port 1 Switch 2 has changed to state DOWN

These go on and on

Thanks,
Ritchie

[Mark Malone · Accepted solution]

The fact you have 2 cables connected and only 2 switches your good to do it live , only 1 stack cable is required to keep the stack live in your instance so you can replace the suspect cable. A reseat of the cable may fix it as well if you don't have a spare handy

[CSCO12063651]

Thanks Mark for the response.