We're planning to migrate from an ONTAP 8.2 7-mode FAS 3240 HA pair to a ONTAP 9.1 cluster system. I created an new SVM as a destination. The filer is used for NFS/CIFS user homes and shares which are mounted by about 2000 client systems (workstations, notebooks, but mostly development servers running Linux, Solairs and AIX).
I plan to take over the IP addresses, NFS and CIFS shares from the old filer, so that the migration appears to be transparent from the client's point of view.
In the copy-based transition guide I read that migration is disruptive to clients. No more details. What does this exactly mean? Will clients with open files on NFS shares just freeze for a few seconds/minutes during cutover? Or will they point to nonexisting filehandles after migration and end up all with "stale NFS handle" errors and require a unmount/reboot? We had this every time we had to migrate from an older ONTAP 7-mode system to a newer 7-mode system, which was every time a pain.
Does the 7-mode transition tool (version 3.2) also migrate all the open file handles to the new system?
Or do we really have to shut down about 2000 clients before storage cutover and boot them after the migration is finished?