Basic Downgrade Steps

Learn the basic steps for downgrading from Adaptive Server 15.5 Cluster Edition to a 15.0.1 Cluster Edition, 15.0.1 Cluster Edition ESDs, and 15.0.3 Cluster Edition. Additional actions are required if you used 15.5 Cluster Edition features. Follow the steps in the Additional Steps If You Used 15.5 Cluster Edition Features Before Downgrading topic.

Adaptive Server 15.5 Cluster Edition provides a procedure called sp_downgrade that is used to help with the downgrade process. This procedure requires “sybase_ts_ role” to be on. The “sa_role” or “sso_role” permissions are required to run this procedure. For detailed information on this system procedure and its syntax see “The New System Procedures” section in the ‘System Changes” chapter of the Adaptive Server New Feature Guide for 15.0.2.

If you have used Pluggable Component Interface (PCI) functionality, and are downgrading to a version of the15.0.1 Cluster Edition or a 15.0.1 Cluster Edition ESD, drop the sybpcidb and restart the old server binary.
If you are downgrading to version 15.0.3 Cluster Edition, rerun installpcidb and restart the old server binary.
Start the 15.5 Cluster Edition server in single user mode, with only one instance running, using dataserver -m option to guarantee that no other user can access Adaptive Server while you are performing the downgrade. See Utility Guide for more details on starting the server in single user mode.
Make sure Adaptive Server 15.5 Cluster Edition is prepared for downgrade by executing sp_downgrade from the master database:
```
sp_downgrade 'prepare', @toversion=<'version'>
, @override = 1
```
The value of “version” may be written as"15.0.1.5","15015","15.0.3.5" or "15035". However, the version entered should be the version you want to downgrade to. sp_downgrade 'prepare' validates the readiness of Adaptive Server 15.5 Cluster Edition for downgrade. This means that sp_downgrade 'prepare' may print messages regarding manual changes required before the downgrade can be completed. Errors reported must be corrected and implications of warnings reported must be understood before you can proceed with further downgrade steps. Refer to the Additional Steps If You Used 15.0.3 Cluster Edition Features Before Downgrading topic for more information on correcting the issues reported by sp_downgrade 'prepare'.
Repeat step 3 until sp_downgrade 'prepare' reports no errors. Your system is now ready to downgrade.
Begin the downgrade process by executing sp_downgrade from the master database:
```
sp_downgrade 'downgrade', @toversion = '15015', @override = 1
```
The version number should be "15.0.1.5","15015","15.0.3.5" or "15035". Once the above command completes successfully there can be no more activity on the 15.5 Cluster Edition server. You must immediately shutdown the 15.5 Cluster Edition server. sp_downgrade 'downgrade' may report that the password for sa and other login accounts has been reset and that the account is locked. In this case, the new password shown by sp_downgrade is used as the password for sa after the downgrade. Any other affected login accounts should be unlocked after the downgrade is complete.
Run - checkpoint and shutdown the old server.
Copy the RUN_SERVER file to the release are of the version to which you are downgrading. Modify the RUN_SERVER file to use the dataserver binary from the release area of the version to which you are downgrading. Remove the -m option when you modify the RUN_SERVER file or ensure the server is not running in single user mode.
Extract the quorum device using:
```
qrmutil --quorum-dev=<dev> --extract-config=quorum.out 
```
1. If you are downgrading to a Cluster Edition version 15.0.1 or a Cluster Edition 15.0.1 ESD, comment these two lines in quorum.out:
```
#installation mode=shared
#membership mode=
```
Rebuild the new quorum device with the old quorum device backup you created by adding this to the dataserver parameters:
```
--buildquorum=force --cluster-input=quorum.out
```
Restart the old server using the modified RUN_SERVER file.
Note: If a downgraded server is booted using the 15.5 configuration file, the new options will cause the message ‘Unknown parameter ‘. The unknown option will be reported only the first time the server is booted. When downgrading to a 15.0.1 Cluster Edition server, user passwords may be reset and printed on the console. Save the output of sp_downgrade 'downgrade', <version> into a file so that the passwords are not lost. The old passwords do not work. Otherwise, you must restart the downgraded server with -psa to regenerate the sa password.
Depending upon whether you are starting from a fresh installation or from a previously upgraded 15.x installation, run previously saved restore_msgs.ebf or instmsgs.ebf from 15.0.1 Cluster Edition or 15.0.3 Cluster Edition if none were saved, before running installmaster for the Cluster Edition.
Restart all instances of the cluster.