Thread 1 cannot allocate new log, sequence 124825, All online logs needed archiving

Last week I faced some interesting issue due to archiver process.

I got connection refused alert from web server. I verified the logs, Application user connections were refused for around 10 minutes.
I verified the oracle database alert log file & we found below information alert.

ARCH: Connecting to console port…
Thread 1 cannot allocate new log, sequence 124825
All online logs needed archiving

In database, log_archive_max_processes value is 2 & redo log file size is 250 MB (3 Groups only).

Why it’s happened?

Due to huge transactions (lot of DML operations – happened unexpectedly in database), archiver not able to archive the online redo log files.

Solution:

1.Increase the log_archive_max_processes from 2 to 5.
2.Add the new online redo log groups (3 groups to 5 groups).
3.Increase the online redo log file size from 250MB TO 500MB.