Reversion issues between release families

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 features introduced in a new release might be incompatible with features of the previous release.

If you need to revert to a previous release of Data ONTAP, call Network Appliance Technical Support for assistance. For more information, see Reverting to a previous release.

General guidelines for reverting from Data ONTAP 6.5

The following guidelines apply when reverting from Data ONTAP 6.5 to an earlier version:

You must disable any 6.5 features before reverting.
You cannot revert to a release earlier than Data ONTAP 6.3.
You cannot revert if an upgrade is in progress.

Upgrade must complete before any reversion is attempted

If you begin the upgrade procedure to Data ONTAP 6.5 and then decide that you want to revert to an earlier Data ONTAP release, you must complete the 6.5 upgrade before reverting.

Reversion with larger inodes

If you upgrade to Data ONTAP 6.5, your filer is upgraded to support larger inodes. There are two instances in which larger inodes can cause a reversion to an earlier release to fail:

While the inode upgrade is still in progress
When there is not enough disk space or there are not enough free inodes in a volume
Note
Reverting to an earlier release can take several hours, depending on the number of total inodes and inodes used on your system.

To determine whether an inode upgrade is still in progress, complete the following steps.

Step	Action
1	Enter the following command: priv set advanced Result The filer prompt now displays an asterisk (*) after the filer name to indicate that you are in advanced mode.
2	Enter the following command: wafl scan status Example If the upgrade is still in progress, the filer displays a message similar to the following: Volume vol1: Scan id Type of scan progress 2 inofile upgrade 849387 of 33554472 Note If an `inofile upgrade` scan type is not displayed, the inode upgrade is done.

Step

Action

Enter the following command:

priv set advanced

Result

The filer prompt now displays an asterisk (*) after the filer name to indicate that you are in advanced mode.

Enter the following command:

wafl scan status

Example

If the upgrade is still in progress, the filer displays a message similar to the following:

Volume vol1:

Scan id       Type of scan          progress

      2       inofile upgrade      849387 of 33554472

Note
If an inofile upgrade scan type is not displayed, the inode upgrade is done.

When more disk space or free inodes are needed for reverting, you see a message similar to the following:

Volume vol1: There are not enough free inodes to revert the ACLs 
with nlinks over 65535.

A minimum of ### inodes needed (maximum ###).

Minimum and maximum inodes needed depends on the number of nlinks over 65,355.

You can free up inodes in a volume by deleting files or by moving files to a volume that has free inodes.

To view the number of used and free inodes, complete the following step.

Step	Action
1	At the filer console, enter the following command: df -i

Excessive subdirectories and hard links

If you have more than 65,533 subdirectories or 65,535 hard links, you must move the extra subdirectories to another directory and delete the extra hard links before you revert. When too many hard links exist during a revert, you will see an error message similar to the following:

Scanning all inodes in volume "vol1" for non-ACL inodes with nlinks 
over 65535 0% done

inode 102, file has too high of an nlink (81519)

inode 101, file has too high of an nlink (90001)

0% done.

Large directories can be reverted but cannot be made larger

Data ONTAP 6.5 allows larger directories than in previous versions. If you have a directory larger than 65,535 KB, the directory will be accessible when you revert to a pre-6.5 version of Data ONTAP and will remain at its current size, but you cannot make it any larger.

Reverting entries in the /etc/exports file

When you upgrade to Data ONTAP 6.5, new access rules are applied to the /etc/exports file. If you revert to a pre-6.5 version of Data ONTAP, the /etc/exports file will be scanned to determine whether it conforms to the pre-6.5 format. If not, the reversion will not proceed until the file has been fixed.

To fix the file, you can edit it manually or use the exportfs -d command to revert the file. Using exportfs -d will fix most of the revert issues. However, some changes to the /etc/exports file are not fixed with the exportfs -d command and cause a message to be sent to the console during a reversion. If any of these issues are not fixed, that line in the /etc/exports file does not load and access is denied for that resource. This happens in the following circumstances:

Lines greater than 4,096 characters, excluding comments
Entries exceeding 256 characters in either the -rw or -root options
Too many entries in the -access option

Data ONTAP has no way to determine whether entries in an access list represent a netgroup or a host name; therefore, no checking is done on names during reversion. If netgroups exist in the -rw and -root options, you must manually edit the file to conform to the pre-6.5 format; otherwise, the export line containing the netgroup does not load and access is denied for that resource.

For more information about the /etc/exports file, see the NetApp exports(5) man page.

RAID-related errors

Updates made to RAID in Data ONTAP 6.5 can sometimes cause problems when you revert to an earlier version, and the reversion may fail. The following is a list of possible problems and the resulting error messages that are sent to the console:

RAID reversion issue	Message with required action
RAID DP volumes are present	There is a raid_dp volume present which cannot be reverted. Downgrade these volumes with `vol options <vol> raidtype raid 4'.
RAID label assimilation in progress	RAID label assimilation in progress. Wait for assimilation to complete before reverting.
Failed Disk Registry in process of being updated	Please wait one moment while RAID updates the Failed Disk Registry.
Sanitized disk present	There are sanitized disks present. Either remove them or issue a `disk sanitize release' to return sanitized disks to the spare pool.
Disk in process of being sanitized is present	There are sanitized disks present. Either wait for the sanitize to complete, or issue a `disk sanitize abort' to return sanitized disks to the spare pool.
Sparecore disk present	There is a sparecore disk present which cannot be reverted. Wait for the sparecore to complete before running revert.

Running a RAID label version that is too new

When you install a pre-6.5 version of Data ONTAP, you might get a message that the RAID label version you are running is either invalid or too new. This can happen when the filer contains disks that were previously upgraded with Data ONTAP 6.5, and were not reverted using the revert_to command. In cases where a disk has not been properly reverted, the following actions occur:

The disk is not assimilated.
The disk is moved to the broken disk pool with "bad label" given as the reason.
An Autosupport notice is sent to Network Appliance and the customer.

SnapLock volumes must be removed before reverting

Before reverting to a pre-6.5 release of Data ONTAP, SnapLock volumes must be removed. For more information about SnapLock, see the Storage Management Guide.

Stale file handles on vFilers

Data ONTAP 6.4 included a change in the Network File System (NFS) file handle format that is not backward compatible with vFiler^TM systems. If you have defined vFiler storage on your system, and you upgrade to 6.4 or later and then revert to an earlier version, 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.

Finding reversion issues for releases earlier than Data ONTAP 6.3

To find reversion issue information for releases earlier than Data ONTAP 6.3, go to the Information Library for Archived Documentation on the NOW site, at http://now.netapp.com/NOW/knowledge/docs/archive_docs.shtml, for a list of documentation for earlier releases of Data ONTAP.

Reversion with home directory paths in the cifs_homedir.cfg file

If you upgrade to Data ONTAP 6.3 or later and convert home directory path entries from the cifs.home_dir option to the cifs_homedir.cfg file, then if 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.