Okay, I was silent for couple of months. I took a much needed break and back to work now. As few of you may already know, I am not a DBA (Certified), yet I have dealt with Oracle databases throughout my career & today was “another day” when I came across something new after restoring RMAN backup to a TEST environment.
Actually the entire “how to document” was provided by a APPS DBA friend (thanks to such geeks who are never bothered about someone else “learning the tricks” and challenging them! Geeks remain geeks) & without giving much attention to few elements, I “successfully” duplicated the 11g R2 database. Once after the database came online, I realized that the instance was pretty slow & immediately monitored the alert logs.
I started reading few entries like following:
Thread 1 cannot allocate new log, sequence 56 Private strand flush not complete Current log# 3 seq# 55 mem# 0: /u01/oratest/TEST/db/apps_st/data/redo03a.log Current log# 3 seq# 55 mem# 1: /u01/oratest/TEST/db/apps_st/data/redo03b.log Beginning log switch checkpoint up to RBA [0x38.2.10], SCN: 5986177240123 Thread 1 advanced to log sequence 56 (LGWR switch) Current log# 4 seq# 56 mem# 0: /u01/oratest/TEST/db/apps_st/data/redo04a.log Current log# 4 seq# 56 mem# 1: /u01/oratest/TEST/db/apps_st/data/redo04b.log Completed checkpoint up to RBA [0x38.2.10], SCN: 5986177240123 Thu Oct 04 12:14:14 2018 Beginning log switch checkpoint up to RBA [0x39.2.10], SCN: 5986177240998 Thread 1 advanced to log sequence 57 (LGWR switch) Current log# 1 seq# 57 mem# 0: /u01/oratest/TEST/db/apps_st/data/redo01a.log Current log# 1 seq# 57 mem# 1: /u01/oratest/TEST/db/apps_st/data/redo01b.log Thread 1 cannot allocate new log, sequence 58 Private strand flush not complete Current log# 1 seq# 57 mem# 0: /u01/oratest/TEST/db/apps_st/data/redo01a.log Current log# 1 seq# 57 mem# 1: /u01/oratest/TEST/db/apps_st/data/redo01b.log Thu Oct 04 12:14:25 2018 Beginning log switch checkpoint up to RBA [0x3a.2.10], SCN: 5986177241136 Thread 1 advanced to log sequence 58 (LGWR switch) Current log# 2 seq# 58 mem# 0: /u01/oratest/TEST/db/apps_st/data/redo02a.log Current log# 2 seq# 58 mem# 1: /u01/oratest/TEST/db/apps_st/data/redo02b.log Thu Oct 04 12:14:47 2018 Thread 1 cannot allocate new log, sequence 59
I landed over a discussion at https://community.oracle.com/thread/364032?start=0&tstart=0 & few others, and at many places I read suggestions towards the redo log files getting filled too fast because of the smaller sizes allocated. I check the production instance, the redo log files were of size 1000M when the TEST instance log files were of size 100M!
So my next requirement was to resize the redo log files without damaging the database.
I came across an excellent post here https://uhesse.com/2010/01/20/how-to-change-the-size-of-online-redologs/ that explains how to create new redo log files and to drop the old ones without affecting the database (or users). The best part is, you don’t even have to take the database offline for any of the suggested activities.
So if you ever face such a situation, give it a try. You would be happy like me :)