ASM communication error & ORA-21561 : OID generation failed

I have faced an issue which had following db alert log snippet,

WARNING: ASM communication error: op 0 state 0x0 (15055)
ERROR: direct connection failure with ASM
WARNING: ASM communication error: op 0 state 0x0 (15055)
ERROR: direct connection failure with ASM
WARNING: ASM communication error: op 0 state 0x0 (15055)
ERROR: direct connection failure with ASM
WARNING: ASM communication error: op 0 state 0x0 (15055)
ERROR: direct connection failure with ASM

Firstly I thougt that it was ASM crash issue or anything about ASM instance.I was not able to connect ASM instance with sqlplus / as sysasm and there was no entry in ASM alert log related with this issue,and also ASM pmon process was alive.

But "sqlplus system/<PASS>" gave me the following error,

ORA-21561 : OID generation failed

According to Metalink and Google search , the problem was likely client hosts file."/ect/hosts" file had machine fully qualified  hostname and shortname. But i have realized that for some reason machine hostname has been changed :) 

After changing to true name of host , trouble has gone.