Follow the procedure in the Xsan 4 Migration Guide when upgrading an existing SAN to Xsan 4 on Yosemite. The following steps might also be required when upgrading your metadata controllers (MDCs).
- Your MDC should be using the latest versions of both OS X and OS X Server.
- Make sure you've configured your DNS properly.
- If you're replacing an old MDC with a new MDC (as described in the migration guide), check that your older MDC is offline. Then make sure your new MDC is configured with the same hostname and IP address as the old MDC. If your SAN uses a dedicated metadata network, the new MDC should have also have a network interface configured with the metadata IP address used by the old MDC.