Tag Archives: Deep inside

ARC and LGWR(TT) processes depending

It seems we depend each other more that we think.

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Chicken-and-egg problem

You might wonder how CSSD, which is required to start the clustered ASM instance, can be started if voting disks are stored in ASM? This sound like a chicken-and-egg problem. Without access to the voting disks there is no CSS, hence the node can’t join the cluster. But without begin part of the cluster, CSSD can’t start the ASM instance. To solve this problem the ASM disk headers have metadata since 11.2. You can use kfed to read the headers of ASM disks containing a voting disk. The kfdhdb.vfstart and kfdhdb.vfend fields tell CSS where to find the voting file. This does not require the ASM instance to be up. Once the voting disks are located, CSS can access them and joins the cluster.

ORA-15074: diskgroup requires rebalance completion

Sometimes when you add or remove disks in ASM diskgroup without rebalancing, you can stumbled upon this error.

SQL> alter diskgroup SOMEGROUP add failgroup FG1 disk 'ORCL:DISK10[0-9]','ORCL:DISK11[0-9]','ORCL:DISK12[0-2]' rebalance power 10;
alter diskgroup SOMEGROUP add failgroup FG1 disk 'ORCL:DISK10[0-9]','ORCL:DISK11[0-9]','ORCL:DISK12[0-2]' rebalance power 10
ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15074: diskgroup SOMEGROUP requires rebalance completion

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