Possible upgrade issues

Reversion issues

Why there might be issues

You might encounter issues if you upgrade and then decide to revert to a previous version of Data ONTAP, because new features introduced in a release might not allow reversion to a previous release. If you need to revert to a previous release of Data ONTAP, call Network Appliance Technical Support for assistance.

Qtree information might be lost

If you revert to a pre-5.1 release, you might lose qtree information.

Caution
To preserve qtree information, make a backup of your data before you upgrade.

NVRAM data might be lost

Starting with version 5.3.4, Data ONTAP supports a new NVRAM format to offer better protection to data logged to the NVRAM.

Because of the new NVRAM format, if you want to revert to a version of Data ONTAP earlier than 5.3.4, you must perform an orderly shutdown of the filer first. A dirty shutdown before booting the filer with a version prior to 5.3.4 causes data stored in the NVRAM to be lost.

Reversion with 520-bps disks

If you upgrade and you have 520-bps disks attached to the filer, the earliest version of Data ONTAP that you can revert to is Data ONTAP 6.1.1.

File security might be lost in a reversion

Because Data ONTAP 6.1.1 or later uses Windows 2000 access control list (ACL) inheritance, if you upgrade and then revert to a pre-6.1 release, you might lose some security information on files.

Reversion with expanded RAID group

If you upgrade and expand the size of any redundant array of independent disks (RAID) group other than the last RAID group you created, you cannot revert to a version earlier than Data ONTAP 6.2.

Reversion with mirrored volumes

If you upgrade and create mirrored volumes, you cannot revert to a version earlier than Data ONTAP 6.2, unless you first unmirror the mirrored volumes.

Users might not be able to log in after reversion

Data ONTAP 6.2 allows longer passwords than previous versions. If you upgrade and create any non-root user passwords, and then revert to a version earlier than 6.2, those users will not be able to log in. To enable those users to log in, you must delete their accounts and then add them back in to the reverted system.

Reversion with home directory paths in the cifs_homedir.cfg file

If you upgrade to Data ONTAP 6.3 and convert home directory path entries from the cifs.home_dir option to the cifs_homedir.cfg file, when you revert to a pre-6.3 release, the filer will attempt to write as many of the paths as possible back to the registry for the cifs.home_dir option. If some of the paths fail to be written to the registry, you might need to manually transfer the paths from the cifs_homedir.cfg file to the cifs.home_dir option. The cifs_homedir.cfg file remains intact during reversion.

Stale file handles on vfilers

Data ONTAP 6.4 includes a change in the Network File System (NFS) file handle format that is not backward compatible. If you have defined vfilers on your system, and you upgrade to 6.4 and then revert to 6.2x or 6.3x, NFS clients might report stale file handles on the vfilers. To prevent this problem, unmount any NFS clients that are mounted on vfilers. You can remount them after reverting.