disk unmirror

Syntax

disk unmirror 
	name = "device_name" 
	[, side = {"primary" | secondary}] 
	[, mode = {retain | remove}]

Parameters

name – is the name of the database device to unmirror. The name must be enclosed in single or double quotes.
side – specifies whether to disable the primary device or the secondary device (the mirror). By default, the secondary device is unmirrored.
mode – determines whether the unmirroring is temporary (retain) or permanent (remove). By default, unmirroring is temporary.
Specify retain when you plan to remirror the database device later in the same configuration. This option mimics what happens when the primary device fails:
- I/O is directed only at the device not being unmirrored.
- The status column of sysdevices indicates that mirroring is deactivated. remove eliminates all sysdevices references to a mirror device.
- The status column indicates that the mirroring feature is ignored.
- The phyname column is replaced by the name of the secondary device in the mirrorname column if the primary device is the one being deactivated.
- The mirrorname column is set to NULL.

Examples

Example 1 – Suspends software mirroring for the database device user_disk:
```
disk unmirror 
name = "user_disk"
```
Example 2 – Suspends software mirroring for the database device user_disk on the secondary side:
```
disk unmirror name = "user_disk", side = secondary
```
Example 3 – Suspends software mirroring for the database device user_disk and removes all device references to the mirror device:
```
disk unmirror name = "user_disk", mode = remove
```

Usage

Disk mirroring creates a software mirror of a user database device, the master database device, or a database device used for user database transaction logs. If a database device fails, its mirror immediately takes over.

disk unmirror disables either the original database device or the mirror, either permanently or temporarily, so that the device is no longer available to the SAP ASE server for reads or writes. It does not remove the associated file from the operating system.
Disk unmirroring alters the sysdevices table in the master database. Back up the master database with the dump database command after each use of disk unmirror. This makes recovery easier and safer in case master is damaged.
You can unmirror a database device while it is in use.
You cannot unmirror any of a database’s devices while a dump database, load database, or load transaction is in progress. The SAP ASE server displays a message asking whether to abort the dump or load or to defer the disk unmirror until after the dump or load completes.
You cannot unmirror a database’s log device while a dump transaction is in progress. The SAP ASE server displays a message asking whether to abort the dump or defer the disk unmirror until after the dump completes.

Note: dump transaction with truncate_only and dump transaction with no_log are not affected when a log device is unmirrored.
Mirror all the default database devices so that you are still protected if a create or alter database command affects a database device in the default list.
When a read or write to a mirrored device is unsuccessful, the SAP ASE server automatically unmirrors the bad device and prints error messages. The SAP ASE server continues to run, unmirrored. A system administrator must restart mirroring with the disk remirror command.
For a report on all SAP ASE devices on your system (user database devices and their mirrors, as well as dump devices), execute sp_helpdevice.
Use disk remirror to reestablish mirroring after it is temporarily stopped with the mode = retain option of the disk unmirror command. If mirroring is permanently disabled with the mode = remove option, you must remove the operating system file that contains the mirror before using disk remirror.

Standards

ANSI SQL – Compliance level: Transact-SQL extension.

Permissions

The permission checks for disk unmirror differ based on your granular permissions settings. You must be using the master database to use disk unmirror.

Setting	Description
Enabled	With granular permissions enabled, you must be a user with `manage disk` privilege.
Disabled	With granular permissions disabled, you must be a user with sa_role. disk unmirror permission is not transferable.

Auditing

Values in event and extrainfo columns of sysaudits are:

Information	Values
Event	24
Audit option	disk
Command or access audited	disk unmirror
Information in `extrainfo`	Roles – current active roles Keywords or options – disk unmirror Previous value – NULL Current value – NULL Other information – name of the disk Proxy information – original login name, if set proxy is in effect