OCP 1Z0 053 124

124.You are managing Oracle Database 11g with an ASM storage with high redundancy. The following 
command was issued to drop the disks from the dga disk group after five hours: 
ALTER DISKGROUP dga OFFLINE DISKS IN FAILGROUP f2 DROP AFTER 5H; 
Which statement is true in this scenario? 
A. It starts the ASM fast mirror resync. 
B. All the disks in the dga disk group would be OFFLINE and the DISK_REPAIR_TIME disk attribute 
would be set to 5 hours. 
C. It drops all disk paths from the dga disk group. 
D. All the disks in the dga disk group in failure group f2 would be OFFLINE and the DISK_REPAIR_TIME 
disk attribute would be set to 5 hours. 
Answer: D 

http://docs.oracle.com/cd/E11882_01/server.112/e10803/config_storage.htm#HABPT4818

4.4.5 Set the DISK_REPAIR_TIME Disk Group Attribute Appropriately

The DISK_REPAIR_TIME disk group attribute specifies how long a disk remains offline before Oracle ASM drops the disk. If a disk is made available before the DISK_REPAIR_TIME parameter has expired, the storage administrator can issue the ONLINE DISK command and Oracle ASM resynchronizes the stale data from the mirror side. In Oracle Database 11g, the online disk operation does not restart if there is a failure of the instance on which the disk is running. You must reissue the command manually to bring the disk online.

You can set a disk repair time attribute on your disk group to specify how long disks remain offline before being dropped. The appropriate setting for your environment depends on how long you expect a typical transient type of failure to persist.

Set the DISK_REPAIR_TIME disk group attribute to the maximum amount of time before a disk is definitely considered to be out of service.

http://docs.oracle.com/cd/E11882_01/server.112/e18951/asmdiskgrps.htm#OSTMG10044

By default, Oracle ASM drops a disk in 3.6 hours after it is taken offline. You can set the DISK_REPAIR_TIME disk group attribute to delay the drop operation by specifying a time interval to repair the disk and bring it back online. The time can be specified in units of minutes (m or M) or hours (h or H). If you omit the unit, then the default unit is hours. TheDISK_REPAIR_TIME disk group attribute can only be set with the ALTER DISKGROUP SQL statement.

ALTER DISKGROUP data SET ATTRIBUTE 'disk_repair_time' = '4.5h'ALTER DISKGROUP data SET ATTRIBUTE 'disk_repair_time' = '270m'

The following example takes disk DATA_001 offline and drops it after five minutes.

ALTER DISKGROUP data OFFLINE DISK DATA_001 DROP AFTER 5m;