我在执行日志备份的时候遇到了加上alter system archive log current; oracle提示log 4 sequence# 697 not archived, no available destinations，导致整个归档进程全部停止，数据库也停止运行了。这是什么原因导致的？

官方对 对 archive log current 的解释是 Specify CURRENT to manually archive the current redo log file group of the specified thread, forcing a log switch. If you omit the THREAD parameter, then Oracle Database archives all redo log file groups from all enabled threads, including logs previous to current logs. You can specify CURRENT only when the database is open. 对 SWITCH LOGFILE的解释 The SWITCH LOGFILE clause lets you explicitly force Oracle Database to begin writing to a new redo log file group, regardless of whether the files in the current redo log file group are full. When you force a log switch, Oracle Database begins to perform a checkpoint but returns control to you immediately rather than when the checkpoint is complete. To use this clause, your instance must have the database open. 这样看，是否用SWITCH LOGFILE更安全一些，避免归档没有完成导致的卡死？

如果你能保留备份前后的归档，不会有其它问题。