Checkpoint not complete

Checkpoint not complete
  Current log# 2 seq# 876 mem# 0: +DATA/tykfdb/onlinelog/group_2.258.983586883
  Current log# 2 seq# 876 mem# 1: +ARCH/tykfdb/onlinelog/group_2.258.983586883
Mon Nov 19 23:16:48 GMT+08:00 2018Thread 1 advanced to log sequence 877 (LGWR switch)
  Current log# 1 seq# 877 mem# 0: +DATA/tykfdb/onlinelog/group_1.257.983586883
  Current log# 1 seq# 877 mem# 1: +ARCH/tykfdb/onlinelog/group_1.257.983586883
 Mon Nov 19 23:17:28 GMT+08:00 2018Thread 1 cannot allocate new log, sequence 878
Checkpoint not complete
  Current log# 1 seq# 877 mem# 0: +DATA/tykfdb/onlinelog/group_1.257.983586883
  Current log# 1 seq# 877 mem# 1: +ARCH/tykfdb/onlinelog/group_1.257.983586883

　　

SQL> select * from v$log;

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIM
------------- ---------
         1          1        871   52428800          2 YES ACTIVE
     20377896 19-NOV-18

         2          1        872   52428800          2 NO  CURRENT
     20383814 19-NOV-18

         3          2        321   52428800          2 YES ACTIVE
     20352997 19-NOV-18

    GROUP#    THREAD#  SEQUENCE#      BYTES    MEMBERS ARC STATUS
---------- ---------- ---------- ---------- ---------- --- ----------------
FIRST_CHANGE# FIRST_TIM
------------- ---------
         4          2        322   52428800          2 NO  CURRENT
     20373660 19-NOV-18

　　

SQL>  select * from v$logfile;

    GROUP# STATUS  TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
IS_
---
         1         ONLINE
+DATA/tykfdb/onlinelog/group_1.257.983586883
NO

         1         ONLINE
+ARCH/tykfdb/onlinelog/group_1.257.983586883
YES

    GROUP# STATUS  TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
IS_
---

         2         ONLINE
+DATA/tykfdb/onlinelog/group_2.258.983586883
NO

         2         ONLINE
+ARCH/tykfdb/onlinelog/group_2.258.983586883

    GROUP# STATUS  TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
IS_
---
YES

         3         ONLINE
+DATA/tykfdb/onlinelog/group_3.265.983587923
NO

         3         ONLINE

    GROUP# STATUS  TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
IS_
---
+ARCH/tykfdb/onlinelog/group_3.259.983587923
YES

         4         ONLINE
+DATA/tykfdb/onlinelog/group_4.266.983587923
NO

    GROUP# STATUS  TYPE
---------- ------- -------
MEMBER
--------------------------------------------------------------------------------
IS_
---
         4         ONLINE
+ARCH/tykfdb/onlinelog/group_4.260.983587923
YES

8 rows selected.

　　

SQL> alter database add logfile group 7 '+DATA/tykfdb/onlinelog/group_7.log' size 200m;

Database altered.

　　

SQL> alter system switch logfile;

System altered.