ASM ab_+ASM.dat hc_+ASM.dat

ab_+ASM.dat : This file generated when asm instance startup. this file  is used by the RDBMS instance to determine the appropriate enviornment information whenever the RDBMS instance connects to the asm instance. If this file is removed, RDBMS instance can not able to connect to ASM

For Example :

[oracle@asmoracle ~]$ cd /u01/app/oracle/11.2.0/grid/dbhome_1/dbs/
[oracle@asmoracle dbs]$ ls
ab_+ASM.dat hc_+ASM.dat initasm.ora init.ora orapw+ASM spfile+ASM.ora

Removed this file or rename this file and then try to startup the RDBMS instance

[oracle@asmoracle dbs]$ mv ab_+ASM.dat ab_+ASM.dat_new

SQL> startup
ORA-01078: failure in processing system parameters
ORA-01565: error in identifying file ‘+DATA/asmoracle/spfileasmoracle.ora’
ORA-17503: ksfdopn:2 Failed to open file +DATA/asmoracle/spfileasmoracle.ora
ORA-27300: OS system dependent operation:open failed with status: 2
ORA-27301: OS failure message: No such file or directory
ORA-27302: failure occurred at: sskgmsmr_7

So I can not able to start the database instance.

After I revert back these file, I can able to connect.

[oracle@asmoracle dbs]$ mv ab_+ASM.dat_new ab_+ASM.dat

SQL> startup
ORACLE instance started.

Total System Global Area 839282688 bytes
Fixed Size 2217992 bytes
Variable Size 524290040 bytes
Database Buffers 310378496 bytes
Redo Buffers 2396160 bytes
Database mounted.
Database opened.

Note that the authentication for the connection is not based on the information in the *.dat file.

But I renamed that file and done some transaction and also I try to create tablespace,  it showing end of file communication error. Again i revert back these file and started the database and again i renamed that file and done some transaction and also created tablespace, now its okay even these file not available. then Why this below error occured before? I want to know more detail, I will share this details once my investigate done.

[oracle@asmoracle dbs]$ mv ab_+ASM.dat  ab_+ASM.dat_new

SQL> conn test/test
Connected.
SQL> create table test(empno number,city varchar2(20));

Table created.

SQL> insert into test values(001, ‘dubai’);

1 row created.

SQL> commit;

Commit complete.

SQL> insert into test values(002, ‘trichy’);

1 row created.

SQL> commit;

Commit complete.

SQL> select count(*) from tab;

COUNT(*)
———-
1

SQL> select * from test;

EMPNO CITY
———- ——————–
1 dubai
2 trichy

 

SQL> conn / as sysdba
Connected.
SQL> create tablespace testtbs datafile ‘+DATA’ size 1m;
create tablespace testtbs datafile ‘+DATA’ size 1m
*
ERROR at line 1:
ORA-03113: end-of-file on communication channel
Process ID: 4644
Session ID: 1 Serial number: 17

 

Again I revert back these file and started the database and then renamed that file but now i done many activities nothing happen. So want to investigate this details

[oracle@asmoracle dbs]$ mv ab_+ASM.dat_new ab_+ASM.dat

SQL> startup
ORACLE instance started.

Total System Global Area 839282688 bytes
Fixed Size 2217992 bytes
Variable Size 524290040 bytes
Database Buffers 310378496 bytes
Redo Buffers 2396160 bytes
Database mounted.
Database opened.

[oracle@asmoracle dbs]$ mv ab_+ASM.dat  ab_+ASM.dat_new

SQL> create tablespace testtbs datafile ‘+DATA’ size 1m;

Tablespace created.

 

hc_+ASM.dat :

EM uses this file for instance health-check monitoring. If this file is removed, the health check information for the instance

will be inaccurate.

Note : Don’t remove these files