Virtual Memory; Disk Subsystem Planning; Array Accelerator: Its Function And Benefit In A Sybase Sql Server Environment; Checkpoints, Housekeeper And Transaction Log Writes - Compaq 117755-003 - ProSignia - 740 Configuration Manual

Page 4 Configuration and Tuning of Sybase System 11 for Microsoft Windows NT on Compaq Servers
Memory requirements are environment-specific. In the "Memory Utilization, Monitoring, and
Optimization" section found later in this document, we provide suggestions on how to detect and
correct low memory situations.

Virtual Memory

During the initial installation of Windows NT, a paging file is setup automatically on the default
boot drive with a size of physical memory + approximately 64 megabytes. In a properly
configured and tuned Sybase SQL Server environment, no paging should occur after the initial
startup of the dataserver. Leave the paging file at its recommended default size.
Sybase System 11 now uses the Windows NT paging file in place of its' own kernel memory
region file. The paging file is accessed by Sybase SQL Server during the initialization and
startup of the database. After the database is online there should be little or no i/o activity to the
Windows NT paging file.
Refer to the Microsoft Windows NT Server, Concepts and Planning Guide for a more in-depth
discussion of the paging file.

Disk Subsystem Planning

The objective of this section is to provide information on the benefits of the Compaq SMART and
SMART-2 SCSI Array Controller Array Accelerator, the pros and cons of various fault tolerance
methods, the selection of the file system, and how disk space is consumed by the combination of
Sybase and Windows NT system level files.
Additional information on disk subsystem configuration and Compaq drive array technology can
be found:
Configuring Compaq RAID Technology for Database Servers ,
Compaq TechNote, P/N 184206-001
Microsoft Windows NT Server, System Guide
Microsoft Windows NT Server, Concepts and Planning Guide
Sybase SQL Server, System Administration Guide

Array Accelerator: Its Function and Benefit in a Sybase SQL Server Environment

The main function of the Array Accelerator is to boost performance of write operations by storing
data in cache memory on the controller. The drive controller informs the host that the write
operation has completed, and writes the data to the hard drives at a more convenient time. The
onboard rechargeable battery pack and mirrored memory banks guarantee data integrity at all
times.
Without the Array Accelerator, the application must wait until each write request is written out to
the disk. Writing to a disk device can be slower than posting the write request in the Array
Accelerator, thus resulting in very different performance characteristics.

Checkpoints, Housekeeper and Transaction Log Writes

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5 megabytes for database kernel and data structures
+ (2% * total data and index space)
+ (51 kilobytes * number of users)
The 51 kilobytes for each user includes 10 kilobytes for
procedures. Make appropriate calculations to determine the
percentage value of procedure cache to total memory using the
result for the "procedure cache" value of sp_configure.
Doc No 143A/0596