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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。
更多 Oracle 相关信息见 Oracle 专题页面 https://www.linuxidc.com/topicnews.aspx?tid=12
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