ALTER GRIDDISK

Purpose

The ALTER GRIDDISK command changes the attributes of all grid disks or specified grid disks.

Caution:

Before changing the name of a grid disk that belongs to an Oracle ASM disk group, ensure that the Oracle ASM disk group is offline.

Syntax

ALTER GRIDDISK { ALL [[ CAPACITYOPTIMIZED | PERFORMANCEOPTIMIZED ] FLASHDISK | HARDDISK ] | gdisk_name1 [,gdisk_name2] ... }
      { [ attribute_filters ] [ ACTIVE | INACTIVE ] [ FLUSH [NOWAIT] | CANCEL FLUSH ] } |
        attribute_name = attribute_value [, attribute_name = attribute_value] ...
              [ attribute_filters ] [NOWAIT] }

Command Options

Starting with Oracle Exadata System Software release 24.1.0, you can optionally specify CAPACITYOPTIMIZED or PERFORMANCEOPTIMIZED before FLASHDISK to alter grid disks on cell disks associated with the specified flash media type.

If you do not fully specify the flash media type, ALL FLASHDISK is equivalent to ALL CAPACITYOPTIMIZED FLASHDISK on Extreme Flash (EF) storage servers containing capacity-optimized flash devices. On all other storage servers, ALL FLASHDISK is equivalent to ALL PERFORMANCEOPTIMIZED FLASHDISK.
If the ALL option is specified with a media type qualifier (FLASHDISK or HARDDISK), the command only alters grid disks on cell disks associated with the specified media type.

Starting with Oracle Exadata System Software release 24.1.0, if you specify the ALL option without a media type qualifier (FLASHDISK or HARDDISK), then the command alters grid disks on the cell disks associated with the primary storage media on the storage server. Specifically:
- On Extreme Flash (EF) storage servers containing capacity-optimized flash devices, ALL with no media type qualifier is equivalent to ALL CAPACITYOPTIMIZED FLASHDISK.
- On Extreme Flash (EF) storage servers containing only performance-optimized flash devices, ALL with no media type qualifier is equivalent to ALL PERFORMANCEOPTIMIZED FLASHDISK.
- On all storage servers containing hard disk drives (HDDs), ALL with no media type qualifier is equivalent to ALL HARDDISK.
Before Oracle Exadata System Software release 24.1.0, if the ALL option is specified without a media type qualifier, the command alters all matching grid disks regardless of media type.
The ACTIVE option notifies CELLSRV to accept I/O as normal for the specified grid disks. The grid disks are visible to the database clients.
The INACTIVE option makes the grid disks visible to the cell administrator, but not visible to the database clients. CELLSRV treats the grid disks as if they were offline. This mode allows management operations on the grid disks. You can do upgrading and testing on the grid disks before making the grid disks visible to database users. This functionality is similar to starting up a database in RESTRICTED mode.

Note:
If the grid disk is used by Oracle ASM and is made INACTIVE when currently in use by a database client, Oracle ASM takes the corresponding Oracle ASM disk offline when I/Os to the disk fail. To make the disk usable again, make the grid disk ACTIVE in the cell, and then bring the corresponding Oracle ASM disk back online in Oracle ASM.
The FLUSH option synchronizes dirty data from the flash cache to the grid disks. Dirty data is data that has not been synchronized with the grid disk.

Synchronization of dirty data can be a lengthy process, depending on the number of bytes to be synchronized. Use the following command to check the progress:
```
LIST GRIDDISK ATTRIBUTES name, flushstatus
```
The CANCEL FLUSH option terminates an earlier flush operation.
The NOWAIT option allows the ALTER command to complete while a resize or flush operation continues, for example:
Starting with Oracle Exadata System Software release 20.1.0, the ALTER GRIDDISK command accepts a WHERE clause, which allows for a specific subset of grid disks to be altered. For example, if you have two sets of grid disks, one for DATA and the other for RECO, you can use the WHERE clause to resize the grid disks from one disk group only, for example:
```
ALTER GRIDDISK size=5T WHERE name like 'RECO.*' 
```
You can use the WHERE clause with either a list of grid disks or with the ALL {FLASHDISK|HARDDISK} option. If you use the WHERE clause and do not specify either a list of grid disks or the ALL {FLASHDISK|HARDDISK} option, then the WHERE clause acts against all disks. Some examples of this syntax are:
```
ALTER GRIDDISK WHERE name like 'DATA.*' INACTIVE

ALTER GRIDDISK ALL FLASHDISK FLUSH NOWAIT
```

Usage Notes

The attributes that can be changed with the ALTER GRIDDISK command are shown as modifiable in Example 7-104.

The length of a grid disk name is limited to 30 characters.
The FLUSH option stops new data from being cached on the specified grid disks until CELLSRV restarts, or the flush operation is canceled.
The FLUSH option is valid for write back disks, not write through disks.
The size attribute can be specified to expand or reduce space allocated to a grid disk.

The size attribute is specified as a number in bytes, unless the suffix M (megabytes) or G (gigabytes) is included with the number value. Grid disk space is allocated in 16 MB units, referred to as allocation units. The actual size allocated is the size of the largest multiple of allocation units less than or equal to the specified size. The minimum value is 16 MB. Values less than 16 MB are rounded up to 16 MB.

If the grid disk is used by Oracle ASM, the corresponding Oracle ASM disk must be resized separately.
A grid disk should not be renamed when the grid disk is being accessed.

If you try to rename a grid disk when it is being accessed, then the operation fails. If the grid disk is used by Oracle ASM, you can make the grid disk inactive or dismount the Oracle ASM disk group to stop access to the grid disk before renaming it.
When an interleaved grid disk is resized, the contents of the grid disk are moved to achieve the interleaved space allocation across the cell disk. The resizing operation can take a few minutes. You can choose to have the data movement proceed as a background process by using the NOWAIT option. Use the LIST GRIDDISK command to check the status.

Note:
Interleaved grid disks are deprecated in Oracle Exadata System Software release 19.1.0.
The cachingPolicy attribute specifies the flash caching policy for the grid disk.

Flash cache is effectively disabled for database files located in a disk group composed of grid disks having cachingPolicy set to none. You may choose this because:
- You want specific database files persisted directly to disk instead of utilizing flash cache.
- You want to dedicate flash cache resources to objects in other database files.
Use the following commands to set the cachingPolicy attribute to none:
```
ALTER GRIDDISK grid_disk_name CACHINGPOLICY="none"
ALTER GRIDDISK grid_disk_name FLUSH
-- Wait for the FLUSH to complete.
ALTER GRIDDISK grid_disk_name CANCEL FLUSH
```
To re-enable caching on the grid disk:
```
ALTER GRIDDISK grid_disk_name CACHINGPOLICY="default"
```