在Oracle DataGuard部署过程中，如果操作不规范，可能遇到很多想不到的问题。有些问题是配置参数不到位，有些是操作不规范遗漏导致。
问题一
主库复制备库到备机时，rman远程登陆主库作为复制的目标库rman无法登陆备机备库，就是下面的命令执行报错：
rman target sys/oracle@dg_orclp auxiliary sys/oracle@dg_orcls
问题原始是从库的TNS配置不规范，缺少(UR=A)，示例配置
DG_ORCLS = (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 172.10.101.36)(PORT = 1521)) (LOAD_BALANCE = off) ) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME =DG_ORCLS) (UR=A) ) )
问题二
主库复制备库到备机时，rman执行duplicat的时，duplicat过程执行报错ORA-17629&ORA-17627：
RMAN> duplicate target database for standby from active database nofilenamecheck; Starting Duplicate Db at 2019-03-10 11:38:4 allocated channel: ORA_AUX_DISK_1 channel ORA_AUX_DISK_1: SID=1811 instance=orcl1 device type=DISK contents of Memory Script: { backup as copy reuse targetfile '/oracle/app/oracle/product/11.2.0/dbs/orapworcl1' auxiliary format '/oracle/app/oracle/product/11.2.0/dbs/orapworcl1' ; }
executing Memory Script Starting backup at 2019-03-10 11:38:43 allocated channel: ORA_DISK_1 channel ORA_DISK_1: SID=4533 instance=orcl1 device type=DISK RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of Duplicate Db command at 03/10/2019 11:38:45 RMAN-05501: aborting duplication of target database RMAN-03015: error occurred in stored script Memory Script RMAN-03009: failure of backup command on ORA_DISK_1 channel at 03/10/2019 11:38:45 ORA-17629: Cannot connect to the remote database server ORA-17627: ORA-12514: TNS:listener does not currently know of service requested in connect descriptor ORA-17629: Cannot connect to the remote database server RMAN>
这个问题比较有趣，配置好TNS后，通过ttnsping和sqlplus sys/oracle@to_orcl as sysdba都正常，就是rman的dumplicat进行从库的复制时报错。该问题的原因是备库的TNS配置中的服务名和主库备库中的log_archive_config='dg_config=()'参数中配置的服务名不一致导致，或者是主库以alter system方式修改了log_archive_config='dg_config'，数据库没有重启，因为log_archive_config参数是静态参数，需要重启数据库服务才能生效。
问题三
在备机通过rman复制主库的时，rman复制过程报错：RMAN-03009&ORA-17628：
Starting backup at 2019-03-10 12:56:20 using channel ORA_DISK_1 channel ORA_DISK_1: starting datafile copy input datafile file number=00003 name= DGSYSTEM/orcl/datafile/undotbs1.261.876856357 output file name= DGSYSTEM/orcl/datafile/undotbs1.340.1002545783 tag=TAG20190310T124734 channel ORA_DISK_1: datafile copy complete, elapsed time: 00:02:55 channel ORA_DISK_1: starting datafile copy input datafile file number=00004 name= DGSYSTEM/orcl/datafile/undotbs2.263.876856383 RMAN-03009: failure of backup command on ORA_DISK_1 channel at 03/10/2019 12:59:21 ORA-17628: Oracle error 19505 returned by remote Oracle server continuing other job steps, job failed will not be re-run
该问题十分严重，通过job failed will not be re-run可以得知，此次的DG复制完全失败了。此问题的原因是存放数据文件相关的ASM磁盘组空间耗尽导致的，因此，在DG主备库开始配置之前，一定要评估好备库的存储并规划好，避免这种因存储空间问题导致DG复制失败的发生。
问题四
DG备库复制完主库后，备库alert日志告警登陆主库被拒绝，主库告警日志提示登陆备库失败。
--备库告警日志 Thu Mar 14 06:51:40 2019 RFS[252]: Assigned to RFS process 3408762 RFS[252]: Opened log for thread 2 sequence 23863 dbid -2091533043 branch 876856333 Thu Mar 14 06:51:42 2019 2019-03-14 06:51:42 logon denied from 172.10.101.61 5964584 oracle with oracle@orcl01 (TNS V1-V3) ¨C oracle@orcl01 (TNS V1-V3) ===username= Thu Mar 14 06:51:42 2019 2019-03-14 06:51:42 logon denied from 172.10.101.61 13697046 oracle with oracle@orcl01 (TNS V1-V3) ¨C oracle@orcl01 (TNS V1-V3) ===username= Thu Mar 14 06:51:43 2019 2019-03-14 06:51:43 logon denied from 172.10.101.61 10486550 oracle with oracle@orcl01 (TNS V1-V3) ¨C oracle@orcl01 (TNS V1-V3) ===username= Thu Mar 14 06:51:43 2019 2019-03-14 06:51:43 logon denied from 172.10.101.61 7274758 oracle with oracle@orcl01 (TNS V1-V3) ¨C oracle@orcl01 (TNS V1-V3) ===username= Thu Mar 14 06:51:43 2019 2019-03-14 06:51:43 logon denied from 172.10.101.61 14156172 oracle with oracle@orcl01 (TNS V1-V3) ¨C oracle@orcl01 (TNS V1-V3) ===username=
--主库告警日志 Thu Mar 14 09:13:45 2019 Error 1017 received logging on to the standby ------------------------------------------------------------ Check that the primary and standby are using a password file and remote_login_passwordfile is set to SHARED or EXCLUSIVE, and that the SYS password is same in the password files. returning error ORA-16191 Error 16191 for archive log file 3 to 'TO_standby' Thu Mar 14 15:49:10 2019 Archived Log entry 203881 added for thread 2 sequence 59940 ID 0x53e28673 dest 1: Errors in file /oracle/app/oracle/diag/rdbms/orcl/orcl2/trace/orcl2_nsa2_2753334.trc: ORA-16191: Primary log shipping client not logged on standby Thu Mar 14 15:49:10 2019 ARCb: Archival destination is a Primary RAC instance: 'TO_standby'
该问题十分严重，会导致备库同步进程抓取归档日志失败。但是，导致该问题的原因是主备库的sys密码文件不一致导致，可能是搭建过程中有人修改了sys密码，处理该问题的方法比较简单，从集群主库任意节点同步sys密码文件即可。
问题五
另外，在DG搭建过程中，可能遇到grid或者oracle通过lsnrctl查看监听状态的时候看到很多服务名，其中有很多l类似：
SYS$SYS.KUPC$C_1_20170318000713.ORCL，sys登陆sqlplus，show parameter service可以发现： NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ service_names string SYS$SYS.KUPC$C_1_20170318000713.orcl.US.ORACLE.COM, SYS$SYS.KUPC$C_1_20170405000711.orcl.US.ORACLE.COM, SYS$SYS.KUPC$S_1_20170314000710.ORCL, SYS$SYS.KUPC$S_1_20170318000713.ORCL, SYS$SYS.KUPC$S_1_20170323000707.ORCL, SYS$SYS.KUPC$S_1_20170331000709.ORCL, SYS$SYS.KUPC$S_1_20170403000701.ORCL, SYS$SYS.KUPC$S_1_20170405000711.ORCL, SYS$SYS.KUPC$C_1_20170314000710.ORCL......
导致该问题的原因是expdp或者impdp被异常终端导致，可以重置service_names或者重启数据库服务加以解决。
