Completing the migration to a new level of IBM Spectrum Scale

You should operate the cluster with the new level of the IBM Spectrum Scale™ until you are sure that you want to permanently migrate to the new level.

When you are ready to migrate the cluster permanently to the new level, you must complete the migration of both the cluster configuration data and all the file systems. If you decide not to migrate to the new level, you can revert to the previous level. For more information, see Reverting to the previous level of GPFS.

After you have migrated all nodes to the latest licensed version of IBM Spectrum Scale, follow these steps to complete the migration:

Verify that the cipherList configuration variable and the SHA message digest are set to valid values. The cipherList variable specifies the security mode for communications among nodes in the cluster and with nodes in other clusters. The SHA message digest is a hash result generated by a cryptographic hash function. Follow these steps:
1. On the command line, enter the command mmauth show . to display the current values. The following listing shows the command and example output:
```
# mmauth show .
Cluster name:        zounds.cluster (this cluster)
Cipher list:         (none specified)
SHA digest:          (undefined)
File system access:  (all rw)
```
2. If the value for the SHA digest is (undefined), enter the following command to generate a public/private key pair and a SHA message digest:
```
mmauth genkey new
```
  Enter mmauth show . again as before and verify that the value for SHA digest is no longer (undefined).
3. If the value for Cipher list is (none specified), enter the following command to set it to AUTHONLY:
```
mmauth update . -l AUTHONLY
```
  Enter mmauth show . again as before and verify that the value for Cipher list is no longer (none specified).
Enter the following command to migrate the cluster configuration data and enable new functionality throughout the cluster:
```
mmchconfig release=LATEST
```
The mmchconfig command lists the names of any nodes that are not available or cannot be reached. If any such nodes are listed, correct the problem and run the command again until it verifies all the nodes and completes successfully.
Important: The command fails if Cipher list is set to a security level lower than AUTHONLY. The only lower security level is EMPTY. If you want to stay at this level, run the following command:
```
 mmchconfig release=LATEST --accept-empty-cipherlist-security
```
If you have not already done so, assign an appropriate GPFS license to each of the nodes in the cluster. See IBM Spectrum Scale license designation for a detailed description of the GPFS license types. To see what the minimum required GPFS license is for each of the nodes in the cluster, enter the following command:
```
mmlslicense -L
```
To assign a GPFS server license to the nodes that require it, enter the following command:
```
mmchlicense server -N NodeList
```
To assign a GPFS client license to the nodes that require it, issue:
```
mmchlicense client -N NodeList
```
Enable backward-compatible format changes or migrate all file systems to the latest metadata format changes.
Attention: Before continuing with this step, it is important to understand the differences between mmchfs -V compat and mmchfs -V full:
- If you issue mmchfs -V compat, only changes that are backward compatible with GPFS 3.5 will be enabled. Nodes in remote clusters that are running GPFS 3.5 will still be able to mount the file system. Nodes running GPFS 3.4 or earlier will no longer be able to mount the file system.
- If you issue mmchfs -V full, all new functions that require different on-disk data structures will be enabled. Nodes in remote clusters running an older GPFS version will no longer be able to mount the file system. If there are any nodes running an older GPFS version that have the file system mounted at the time this command is issued, the mmchfs command will fail.
To enable backward-compatible format changes, issue the following command:
```
mmchfs FileSystem -V compat
```
To migrate all file systems to the latest metadata format changes, issue the following command:
```
mmchfs FileSystem -V full
```
Certain new file system features may require additional processing that cannot be handled by the mmchfs -V command alone. To fully activate such features, in addition to mmchfs -V, you will also have to run the mmmigratefs command. An example of such a feature is enabling fast extended attributes for file systems older than GPFS 3.4.

Note: The first mount of a file system after running mmchfs -V might fail with a no-disk-space error. This might occur if the file system is relatively low on metadata disk space (10% or less free). The user should be able to mount the file system without problem after the initial failed mount.
To activate fast extended attributes, issue the following command:
```
mmmigratefs FileSystem --fastea
```
If you use the mmbackup command to back up your file system, a full backup may be required if a full backup has never been performed with GPFS 3.3 or later. For more information, see File systems backed up using GPFS 3.2 or earlier versions of mmbackup in IBM Spectrum Scale: Administration and Programming Reference.