Compaq ProLiant 6000 Software Manual page 15

ECG052.0897
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HITE APER
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4.5
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500 1000
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Figure 5. Exchange Disk Queue Length (Configuration B)
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Disk I/O Profiling
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An important technique in capacity and performance planning and analysis is I/O profiling. It is
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. . necessary to plan for the disk I/O capacity that your application will require in production. Once
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again, workload characterization is key to making this planning successful. With proper workload
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characterization and simulation, the I/O requirements for the disk subsystem can be observed, and
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the subsystem design can reflect those observations.
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Microsoft Exchange Server is, in a generic sense, a client/server transaction-based database
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application. As such, the disk I/O profile is much like that of a database engine such as Microsoft
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SQL Server. Microsoft Exchange Server stores data in two key files, PRIV.EDB and PUB.EDB,
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. . which hold private data (Mail) and public data (Public Folders). A third file, DIR.EDB stores
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Exchange Server directory information. Two additional areas of interest are Queues (IMC, MTA,
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etc.) and Log files.
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It is important to understand the types of disk I/O generated by access to each of these key data
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file areas in Microsoft Exchange Server. For the Exchange Server data files (PRIV, PUB, and
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DIR), the access patterns are random READ and WRITE (approximately 70% READ, 30%
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WRITE) in nature. For the Log files, the access patterns are sequential WRITE in nature.
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This information is key to designing your disk subsystem to deliver the I/O capacity required by
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the production user load. For example, understanding not only the volume of disk I/Os but also
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the type (READ or WRITE) is a requirement for making choices about RAID levels and number
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of drives (See Compaq White Paper Configuring Compaq RAID Technology for Database
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Servers).
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15
Disk Queue Length
(Hardware Configuration B)
1500 2000 2500
User Load
Exchange IS
Exchange LOG
OS/Pagef ile
3000