I create a tablespace based on an Oracle ASM disk group with two physical disks, and create a table with 499999 rows to make sure the data distributed on two disks evenly.
SQL> select disk_number, name,path from v$asm_disk;
DISK_NUMBER NAME PATH
----------- ---------------- ------------------------------
0 TEST_0000 D:\ORACLEASM\FILE01.ASM
1 TEST_0001 D:\ORACLEASM\FILE02.ASM
SQL> create table emp_asm tablespace asmdemo as
2 select * from emp_bak where rownum < 500000;
In the first case, we don't lost any disk, so we should get exactly 499999 rows back, take the following steps in AUL for Oracle ASM to read the Oracle data file out of ASM disk group.
ASM> disk disk.txt
2 ASM disks opened.
---- -----------------------------------
0 d:\oracleasm\file01.asm
1 d:\oracleasm\file02.asm
ASM> scan
RFN File Size Blocks
---- --------------- ----- --------
5 aulasm_0005.dbf 25 3079
ASM> create file aulasm_0005.dbf size 26
ASM> open rfn 5 file aulasm_0005.dbf
RFN File
---- ---------------------------------------------------------
5 aulasm_0005.dbf
ASM> restore
Restore by ASM extent map file.
The we recover the data with AUL utility, we can see that all rows are recovered, no data loss!
AUL> unload object 13456 to 13456.txt;
2011-04-18 14:52:45
Sucessfully unload 499999 rows ...
2011-04-18 14:53:05
In the second case, we supposed to lost the second disk. Take the following steps in AUL for Oracle ASM to read the Oracle data file out of ASM disk group.
ASM> disk disk.txt
1 ASM disks opened.
---- -----------------------------------
0 d:\oracleasm\file01.asm
ASM> scan
RFN File Size Blocks
---- --------------- ----- --------
5 aulasm_0005.dbf 25 3079
ASM> create file aulasm_0005.dbf size 26
ASM> open rfn 5 file aulasm_0005.dbf
RFN File
---- ---------------------------------------------------------
5 aulasm_0005.dbf
ASM> restore
Restore by ASM extent map file.
The we recover the data with AUL utility, we can see that about half of the rows are recovered as expected.
AUL> unload object 13456 to 13456.txt;
2011-04-18 14:55:09
Sucessfully unload 257375 rows ...
2011-04-18 14:55:20
In the third case, we supposed to lost the first disk. Take the following steps in AUL for Oracle ASM to read the Oracle data file out of ASM disk group.
ASM> disk disk.txt
1 ASM disks opened.
---- -----------------------------------
0 d:\oracleasm\file02.asm
ASM> scan
RFN File Size Blocks
---- --------------- ----- --------
5 aulasm_0005.dbf 24 3071
ASM> create file aulasm_0005.dbf size 26
ASM> open rfn 5 file aulasm_0005.dbf
RFN File
---- ---------------------------------------------------------
5 aulasm_0005.dbf
ASM> restore
Restore by ASM extent map file.
The we recover the data with AUL utility, we can see that another half of the rows are recovered as expected.
AUL> unload object 13456 to 13456.txt;
2011-04-18 14:57:30
Sucessfully unload 242624 rows ...
2011-04-18 14:57:40
We summarised the rows of the incomplete recovery cases, it's exactly matched with the rows of the complete recovery, we can see that it works fine on Oracle ASM data recovery.