Sybase数据库：日志过大导致不能启动

　2008-03-27 15:09:07　来源：WEB开发网　　　

核心提示：问：有个问题问一下，关于SYBASE的：我打开数据库总是提醒：cannot open transaction log file-cannot use log file "hms2000.log" since it is shorter than experted，Sybase数据库：日志过大导致不能

问：有个问题问一下，关于SYBASE的：我打开数据库总是提醒：cannot open transaction log file-----cannot use log file "hms2000.log" since it is shorter than experted。我直接删除了日志，也不能正常启动，说找不到文件。请问这是怎么回事啊？附上出错的日志记录：

I. 10/09 09:58:38. Sybase Adaptive Server Anywhere Network Server Version 7.0.2.1402 I. 10/09 09:58:38. This software contains confidential and trade secret information of I. 10/09 09:58:38. Sybase, Inc.　Use, duplication or disclosure of the software and I. 10/09 09:58:38. documentation by the U.S. Government is subject to restrictions set forth I. 10/09 09:58:38. in a license agreement between the Government and Sybase, Inc. or other I. 10/09 09:58:38. written agreement specifying the Government's rights to use the software I. 10/09 09:58:38. and any applicable FAR provisions, for example, FAR 52.227-19. I. 10/09 09:58:38.　 I. 10/09 09:58:38. Copyright 1989-2000 Sybase, Inc.　All rights reserved. I. 10/09 09:58:38. All unpublished rights reserved. I. 10/09 09:58:38.　 I. 10/09 09:58:38. Sybase, Inc. 6475 Christie Avenue, Emeryville, CA 94608, USA I. 10/09 09:58:38. Networked Seat (per-seat) model. Access to the server is limited to 99 seat(s). I. 10/09 09:58:38. This server is licensed to: I. 10/09 09:58:38.　　lb I. 10/09 09:58:38.　　 I. 10/09 09:58:38. 10240K of memory used for caching I. 10/09 09:58:38. Minimum cache size: 10240K, maximum cache size: 230848K I. 10/09 09:58:38. Using a maximum page size of 1024 bytes I. 10/09 09:58:38. Starting database "XXXXXXX" (C:Program Filessybase数据服务器XXXXXXX.db) at Sun Oct 09 2005 09:58 I. 10/09 09:58:38. Database recovery in progress I. 10/09 09:58:38.　　Last checkpoint at Sat Oct 08 2005 19:15 I. 10/09 09:58:38.　　Checkpoint log... I. 10/09 09:59:03.　　Transaction log: XXXXXXX.LOG... E. 10/09 09:59:03. Error: Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected I. 10/09 09:59:03. Error: Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected E. 10/09 09:59:03. Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected I. 10/09 09:59:04. Database server stopped at Sun Oct 09 2005 09:59 I. 10/09 10:58:33. Sybase Adaptive Server Anywhere Network Server Version 7.0.2.1402 I. 10/09 10:58:33. This software contains confidential and trade secret information of I. 10/09 10:58:33. Sybase, Inc.　Use, duplication or disclosure of the software and I. 10/09 10:58:33. documentation by the U.S. Government is subject to restrictions set forth I. 10/09 10:58:33. in a license agreement between the Government and Sybase, Inc. or other I. 10/09 10:58:33. written agreement specifying the Government's rights to use the software I. 10/09 10:58:33. and any applicable FAR provisions, for example, FAR 52.227-19. I. 10/09 10:58:33.　 I. 10/09 10:58:33. Copyright 1989-2000 Sybase, Inc.　All rights reserved. I. 10/09 10:58:33. All unpublished rights reserved. I. 10/09 10:58:33.　 I. 10/09 10:58:33. Sybase, Inc. 6475 Christie Avenue, Emeryville, CA 94608, USA I. 10/09 10:58:33. Networked Seat (per-seat) model. Access to the server is limited to 99 seat(s). I. 10/09 10:58:33. This server is licensed to: I. 10/09 10:58:33.　　lb I. 10/09 10:58:33.　　 I. 10/09 10:58:33. 10240K of memory used for caching I. 10/09 10:58:33. Minimum cache size: 10240K, maximum cache size: 230848K I. 10/09 10:58:33. Using a maximum page size of 1024 bytes I. 10/09 10:58:33. Starting database "XXXXXXX" (C:Program Filessybase数据服务器XXXXXXX.db) at Sun Oct 09 2005 10:58 I. 10/09 10:58:33. Database recovery in progress I. 10/09 10:58:33.　　Last checkpoint at Sat Oct 08 2005 19:15 I. 10/09 10:58:33.　　Checkpoint log... I. 10/09 10:58:55.　　Transaction log: XXXXXXX.LOG... E. 10/09 10:58:55. Error: Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected I. 10/09 10:58:55. Error: Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected E. 10/09 10:58:55. Cannot open transaction log file -- Can't use log file "XXXXXXX.LOG" since it is shorter than expected I. 10/09 10:58:57. Database server stopped at Sun Oct 09 2005 10:58

答：首先要确定的一点：直接删除日志的方法是不可取的。您的这个问题，是因为日志没有及时整理导致自身过大，使数据库不能正常启动。

我们知道，SYBASE　SQL Server用事务（Transaction）来跟踪所有数据库的变化。事务是SQL　Server的工作单元。一个事务包含一条或多条作为整体执行的T-SQL语句。每个数据库都有自己的事务日志（Transaction　Log），即系统表（Syslogs）。事务日志自动记录每个用户发出的每个事务。日志对于数据库的数据安全性、完整性至关重要，我们进行数据库开发和维护必须熟知日志的相关知识。

一、SYBASE　SQL Server 如何记录和读取日志信息

SYBASE　SQL Server是先记Log的机制。每当用户执行将修改数据库的语句时，SQL　Server就会自动地把变化写入日志。一条语句所产生的所有变化都被记录到日志后，它们就被写到数据页在缓冲区的拷贝里。该数据页保存在缓冲区中，直到别的数据页需要该内存时，该数据页才被写到磁盘上。若事务中的某条语句没能完成，SQL　Server将回滚事务产生的所有变化。这样就保证了整个数据库系统的一致性和完整性。

二、日志设备

Log和数据库的Data一样，需要存放在数据库设备上，可以将Log和Data存放在同一设备上，也可以分开存放。一般来说，应该将一个数据库的Data和Log存放在不同的数据库设备上。这样做有如下好处：一是可以单独地备份Backup　事务日志；二是防止数据库溢满；三是可以看到Log的空间使用情况。

所建Log设备的大小，没有十分精确的方法来确定。一般来说，对于新建的数据库，Log的大小应为数据库大小的30%左右。Log的大小还取决于数据库修改的频繁程度。如果数据库修改频繁，则Log的增长十分迅速。所以说Log空间大小依赖于用户是如何使用数据库的。此外，还有其它因素影响Log大小，我们应该根据实际操作情况估计Log大小，并间隔一段时间就对Log进行备份和清除。

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