ORACLE ASM, 如果一个DiskGroup下面,创建了两个FailGroup,然后是normal 冗余,其中一个FailGroup损坏了会怎样.
这是ocp中的一道题, C 答案说,control1 FG坏了, 会把数据转移到另一个FG, 可是 都坏了,还怎么转移啊????
求解答
我不理解,很不理解, 求解答.
QUESTION 38
A database instance is using an Automatic Storage Management (ASM) instance, which has a diskgroup,
DGROUP1, created as follows:
SQL> CREATE DISKGROUP dgroup1 NORMAL REDUNDANCY
FAILGROUP controller1 DISK '/devices/diska1', '/devices/diska2'
FAILGROUP controller2 DISK '/devices/diskb1', '/devices/diskb2' ;
What happens when the whole CONTROLLER1 Failure group is damaged?
A. The transactions that use the diskgroup will halt.
B. The mirroring of allocation units occurs within the CONTROLLER2 failure group.
C. The data in the CONTROLLER1 failure group is shifted to the CONTROLLER2 failure group and implicit
rebalancing is triggered.
D. The ASM does not mirror any data and newly allocated primary allocation units (AU)are stored in the
CONTROLLER2 failure group.
Answer: C
------解决思路----------------------
C不对，应该选D
A 是错的，因为数据存在镜像，数据库不会因此宕掉
B 是错的，镜像发生在不同的failgroup之间，而不是同一个failgroup之内的asm_disk间进行镜像
C 是错的，CONTROLLER1整个损坏掉，数据库能正常运行，但数据只剩下CONTROLLER2中的一份。当CONTROLLER2中的一块asm_disk发生故障，才会从对应镜像的CONTROLLER1中将数据转移过来，并进行rebalance
D 正确。此时数据只剩下一份，不存在镜像。primary AU储存在CONTROLLER2中
How Oracle ASM Manages Disk Failures
Depending on the redundancy level of a disk group and how you define failure groups, the failure of one or more disks could result in either of the following:
■The disks are first taken offline and then automatically dropped. In this case, the disk group remains mounted and serviceable. In addition, because of mirroring, all of the disk group data remains accessible. After the disk drop operation, Oracle ASM performs a rebalance to restore full redundancy for the data on the failed disks.
■The entire disk group is automatically dismounted, which means loss of data accessibility.