Database Version : 11.2.0.2
Real Application Cluster — > ASM

How error look like in Database Alert log :

WARNING: Read Failed. group:1 disk:4 AU:11852 offset:892928 size:8192
WARNING: failed to read mirror side 1 of virtual extent 1722 logical extent 0 of file 285 in group [1.4277692974] from disk DATA01_0004  allocation unit 11852 reason error; if possible,will try another mirror side
Errors in file /home/app/oracle/diag/rdbms/absnl/ABSNL1/trace/ABSNL1_ora_24108.trc:
WARNING: Read Failed. group:1 disk:4 AU:11852 offset:892928 size:8192
WARNING: failed to read mirror side 1 of virtual extent 1722 logical extent 0 of file 285 in group [1.4277692974] from disk DATA01_0004  allocation unit 11852 reason error; if possible,will try another mirror side

 For the First time when I see this error i thought i had problem in my storage (ASM) But after checking And everything was Ok i start search at Http://Support.oracle.com

Yes it’s Bug , and the Bug Number is 10422126.

you can Check Some Notes related to this issue which You should download Patch and apply it or upgrade to 11.2.0.3

WARNING: Failed To Read Mirror Side 1 continuously reported in the alert log [ID 1289905.1]
WARNING: failed to read mirror side 1 of virtual extent ….. [ID 1274852.1]

Thank you
Osama Mustafa