今天我们来讨论的话题是关于Oracle 28500的。Oracle 28500是一个系统级错误码，表示数据库启动过程中遇到问题。该错误码较为常见，有很多原因可以导致它的出现，下面我们将通过举例来讲述这些原因。

错误原因1：数据库配置错误。常见的配置错误包括错误的监听器名称，错误的启动参数等。例如，如果监听器名称与数据库实例名称不匹配，那么就会导致28500错误。

LSNRCTL>start
Starting /u01/app/oracle/product/10.2.0/db_1/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.1.0 - Production
System parameter file is /u01/app/oracle/product/10.2.0/db_1/network/admin/listener.ora
Log messages written to /u01/app/oracle/product/10.2.0/db_1/network/log/listener.log
Error listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))
TNS-12545: Connect failed because target host or object does not exist
 TNS-12560: TNS:protocol adapter error
TNS-00515: Connect failed because target host or object does not exist
Linux Error: 111: Connection refused
Listener failed to start. See the error message(s) above...

错误原因2：Oracle实例不可用。实例可能因为各种原因无法启动，例如数据文件丢失，控制文件损坏，或者由于网络问题而无法在节点之间进行通信等。

WARNING: Oracle instance running on a system with low open file descriptor limit. Tune your system to increase this limit to avoid severe performance degradation.
ORACLE_HOME = /usr/lib/oracle/xe/app/oracle/product/10.2.0/server
System name:	Linux
Node name:	docker
Release:	4.4.0-145-generic
Version:	#171-Ubuntu SMP Tue Mar 26 12:43:40 UTC 2019
Machine:	x86_64
Instance name: XE
Redo thread mounted by this instance: 0
Oracle process number: 7
Unix process pid: 129, image: oracleXE (LOCAL=NO)
*** 2019-08-30 07:40:59.008
*** SERVICE NAME:() 2019-08-30 07:40:59.008
*** SESSION ID:(37.1) 2019-08-30 07:40:59.007
*** 2019-08-30 07:40:59.007
ksvcreate: Process(ora_xe) creation failed
krm_create: unable to create process
ORA-27102: out of memory
Linux-x86_64 Error: 12: Cannot allocate memory
Additional information: 1418
Additional information: 32776
ORA-10997: another startup/shutdown operation of this instance inprogress

错误原因3：数据库管理员错误。例如，尝试启动不正确的数据库版本，或者没有root或oracle用户权限来执行必要的操作。

oracle@oracle-vm:~$ svcadm enable svc:/application/database/oraclead1:default
svcadm: Pattern 'svc:/application/database/oraclead1:default' doesn't match any instances
oracle@oracle-vm:~$ svcadm enable svc:/application/database/orapmc1:default
svcadm: svc:/application/database/orapmc1:default: The instance "orapmc1" does not exist.

错误原因4：主机或操作系统错误。例如，主机资源不足，缺失必要的库文件，或者操作系统与数据库不兼容等问题。

Oracle High Availability Services on the local node is not running
CRS-4000: Command Status failed, or completed with errors.
CRS-4639: Could not contact Oracle High Availability Services
CRS-4000: Command Status failed, or completed with errors.
CRS-4639: Could not contact Oracle High Availability Services

在发现Oracle 28500错误时，我们必须立即采取必要的措施来解决这个问题。如果我们能够快速解决问题，将有助于提高数据库的可靠性和稳定性。