why the archived log of thread 1 was sometimes generated under the archive destination of thread 2 ?

Sep 18, 2015 7:24AM

Our environment is a 2-node RAC, sometimes I find that the information of archiving redolog of thread 1 is recorded in alert.log of thread 2.

For example,following information can be seen from the thread 2's alert.log :

Tue Aug 18 03:28:17 2015

Archived Log entry 343061 added for thread 1 sequence 202057 ID 0x24c8e4e9 dest 1

And the archived log which has sequence #202057 is created under the archive destination of thread 2.

---query on v$archived_log : thread#!=ARCHIVAL_THREAD#

select sequence#,thread#,archival_thread# from v$archived_log where creator='FGRD' and thread#=1

SEQUENCE# THREAD# ARCHIVAL_THREAD#

--------------- -------- --------------------

202057 1 2

Any document or URLs which can explain this behaviour？ I have spent much time to search on the web but did not get any valueable findings.

Database - RAC/Scalability (MOSC)