SUNDB工具gsyncher说明

1. 定义
   gsyncher为SUNDB提供的同步shared memory的Log与磁盘的logfile的工具。
   SUNDB通过共享内存管理进程之间的数据，gamster管理其内存，如果gmaster死机，就无法访问已上传在共享内存中的数据。无法进行logging, data flush等操作，由gsyncher来代替其作用。

2. gsyncher特点
   ● 数据库运行的过程中无法执行gsyncher。
   ● 可执行gsyncher的服务器STARTUP阶段为OPEN阶段。
   ● 执行gsyncher时，关闭访问shared memory的其他所有应用程序。
   ● gsyncher执行过程中可能发生logfile切换，此时，编写controlfile。
   ● gsyncher提前备份controlfile与写入log的logfile。
   ● 复原已损坏的controlfile之后才能执行gsyncher。

3. 用法
   gsyncher [options]
   主要选项
   -l, --log: 执行时输出log信息到屏幕上。输出的log信息保存在默认存储位置$SUNDB_DATA/trc/gsyncher.trc。
   -h, --home: 设置home目录
   -b, --backup-path: 设置备份目录

4. 例子
   默认设置在gmaster非正常终止时被gmon utility自动执行，所以可以手动确认gsyncher的运行状态。手动执行需终止gmon后重启gmon。

shell> gmon –stop

 Copyright (C) 2010 SUNJESOFT Inc. All rights reserved.
 Release Venus.3.1.22 revision(27014)

gmon is stopped.


在SUNDB运行状态下使用KILL -9命令强制结束gmaster后运行gsyncher。
gmon is stopped.
$ gsyncher -l

 Copyright (C) 2010 SUNJESOFT Inc. All rights reserved.
 Release Venus.3.1.22 revision(27014)


[SHARED MEM] Attached to shm - Name(_STATIC), Key(542311)
[CLEAR PROCESS] Process 'gsql' is cleared.
[CLEAR PROCESS] Process 'gbalancer' is cleared.
[CLEAR PROCESS] Process 'gdispatcher' is cleared.
[CLEAR PROCESS] Process 'gdispatcher' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.
[CLEAR PROCESS] Process 'gserver' is cleared.

[CONTROLFILE] backup controlfile done - directory '/home/Sundb_data/backup'

[FLUSH] Log buffer flushed - Log group from id (0) to (0), lsn from (172380) to (172382), total buffer (512) bytes

[SHARED MEM] Detached from shm.

[FINI] Log sync complete.

删除共享内存段后重启SUNDB。