We're in the process of upgrading 3750 switch stacks in our organization. The stack varies from 2 to 5 switches. We have upgraded about 15 stacks so far. But 2 out of 15 stacks, however, have failed during reload. We had to disconnect the switches from the stack, boot them one at a time then reconnect.
It doesn't seem like the IOS is the issue. I'm guessing the issue may have something to do with the priority settings on the switches. All switches in the stack have a priority of 1. However, the other stacks that have successfully reloaded after the IOS upgarde have the same priority 1 on the switches as well.
We have several stacks left to upgrade and we feel that we may run in to the same issue again with one of more of the stacks. Has anyone run in to this issue before? Should we set the priority number of the switches (ex: 15, 14, 13, etc.), instead of leaving the default setting of 1. Or is the issue caused by something else?
Any comment is appreciated. Thanks.