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农业银行总行1998年以来正式推广了新版网络版综合业务统计信息系统,该系统是基于WindowsNT4.0平台,采用客户/服务器模式,以Microsoft SQL Server为基础建立起来的大型数据库应用程序,系统界面友好、操作简便,计算、分析、检索功能非常强大,为保证农业银行系统及时进行纵向和横向业务数据采集、按照不同要求生成统计报表,进行全面业务活动分析提供了强有力的保障。但在这套程序的推广、维护中笔者发现系统有时运行速度较慢,特别是在Win95客户端操作时尤为严重,经过排除网线连接等硬件可能带来的影响后上述问题仍然存在。笔者经过仔细摸索,发现系统对硬、软件的要求较高,为充分发挥设计效能,达到最佳运作效果,需要对计算机硬、软件系统进行较为完备的性能测试与最佳配置,特别是内存配置的好坏对系统的运行速度具有决定性的作用。下面,笔者就如何优化SQLServer数据库服务器的内存配置提出一些认识和看法。
一、有关内存的基本概念
1?物理内存与虚拟内存
WindowsNT使用两类内存:物理内存与虚拟内存。
物理内存:作为RAM芯片安装在计算机内部的存储器。
虚拟内存:用于模拟RAM芯片功能的磁盘(硬盘)空间,其实质是通过将内存中当前没有使用的部分内容临时存储到磁盘上,使系统可以使用到比机器物理内存更多的内存。
2?分页和分页文件
WindowsNT系统通过使用磁盘空间使得对内存的需求得到部分缓解,从而使用到比物理内存更多内存的技术就称为“交换”或分页,也就是通常所说的虚拟内存技术。通常Windows NT 4.0系统安装时将在引导驱动器上设置一个大小为16MB的交换(分页)文件(pagefile.sys)。
二、优化Windows NT 4.0系统内存配置
在大多数情况下,为了充分发挥Windows NT 4.0系统效能,内存的作用比起处理器的处理能力更具有影响力,特别是在客户/服务器模式环境下更是如此,因为通常在这种环境下并不十分强调处理器的能力,相反却十分注重是否采用足够的内存来满足各个客户的应用需要。此外,为了获得容错功能和保护应用程序,保证应用程序高速运行、充分发挥设计功能都需要有足够多的内存,特别是工业绘图设计和各种工程应用程序更需要占用大量的内存来进行复杂的计算。
物理内存(RAM)方便快速的优点显而易见,但由于其价格昂贵,也就不可能做到多多益善了,因此通过合理优化内存配置、扩充虚拟内存提高计算机运算速度也就成了一项很重要的应用技术手段。
1?保证Windows NT系统基本内存需求
Windows NT 4.0系统至小应配置12MB内存,16MB内存基本够用,正常情况下保证NT系统有32MB内存就可以了,因为并不是所有的16MB基本内存在任何时候都被同时使用。如果添加一些服务和应用程序,则对内存的需求就会急剧增大。如:
(1)添加网络服务需要4MB内存空间;
(2)容错功能和系统保护功能需要8MB内存(如磁盘镜像和分条功能);
(3)进行图形图象处理需要增加16MB内存空间;
(4)安装VC、VB开发系统需要增加16MB内存空间;
另外,如在Windows NT上构建大型数据库如SYBASE、Microsoft SQL Server等,对内存的需求就更多了。
2?优化内存性能
为了使WindowsNT不至于过分占用较多的内存或者浪费处理器的时间用于换页,可以采用以下方法优化内存性能。
(1)减少显示颜色的数量;
(2)降低显示分辨率;
(3)尽可能不使用或使用位宽度较小的墙纸;
(4)关闭不需要的服务程序或驱动程序,尽量不要在服务器上使用其它应用程序。
停用服务或驱动程序的操作步骤如下:
①确定需要停用的服务或驱动程序的名称;
②从“控制面板”中双击“服务”或“设备”图标;
③在列表中选择想要停用的服务或设备驱动程
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