1.错误描述

在日常Oracle数据库巡检时，发现主机上 /u01 分区空间写满，查看Oracle 数据库的日志发现：

Errors in file /u01/app/oracle/diag/rdbms/sljj/sljj2/trace/sljj2_ora_55991.trc:
ORA-01115: IO error reading block from file 221 (block # 1991486)
ORA-15055: unable to connect to ASM instance
ORA-15055: unable to connect to ASM instance
ORA-01115: IO error reading block from file 221 (block # 1991486)
ORA-15055: unable to connect to ASM instance
ORA-15055: unable to connect to ASM instance
Errors in file /u01/app/oracle/diag/rdbms/sljj/sljj2/trace/sljj2_ora_50157.trc:
ORA-01115: IO error reading block from file 217 (block # 453196)
ORA-15055: unable to connect to ASM instance
ORA-15055: unable to connect to ASM instance
ORA-01115: IO error reading block from file 217 (block # 453196)
ORA-15055: unable to connect to ASM instance
ORA-15055: unable to connect to ASM instance

此前发现日志写满，手工删除了日志。但未重启数据库。

2.错误分析

根据以上日志，一开始认为是数据库出现了问题。但是冷静分析，发现手工删除的数据库日志，磁盘空间并未全部释放。

3.解决方法

重启该节点的数据库实例；
发现磁盘空间释放；

该问题得到解决。

记录改故障的处理过程。