Calculating the number of file operations

This topic helps you determine the calculate the number of file operations per second.

Context

For various application types, the following table provides mapping between application transaction rate (APPOP) and file operations (FOP), that is, the number of expected file operations for each application transaction, and file operations (FOP) to metadata server operation (the number of expected metadata server operations for each file operation). The values in this table are based upon IBM internal testing and estimates based upon those test results.

Application type Typical metric Average FOP/APPOP Average metadata server OP/FOP
Mail server Mails per second 20 3%
Oltp database back end Transactions per second 2 5%
Data Warehouse database back end Tuples per second 0.1 10%
Office workgroup Documents per second 10 1%
Web server Connections per second 5 10%
Web proxy Pages per second 15 10%
Peer-to-peer Files per second 12 10%
Network File System Serving Megabytes per second 30 10%
Common Internet File System Serving Megabytes per second 30 10%
Compile Build (Development) Files built per second 10 5%
User Folder Serving Files used per second 5 3%

This table can be used to help estimate the rate of Metadata server operations generated by your application, given your application’s transaction serving rate. For example, if you have a mail server and you expect to serve 50 mails per second, the expected number of Metadata server operations generated would be 30.

After the number of metadata server operations is determined for your application, adjust the estimate using the previous table and answers to the application and environment questionnaire. Use the adjustment factors in the following table, as applicable.

  Adjustment factor
Average file size larger than 500 Mb + 20%
File hotset > 10K + 20% for each 10K
Windows client + 20%
Number of clients (Uniform) Multiply By # of Clients
Average directory size larger than 100 objects + 10%
Special application dirwalk + 20%
Object-sharing R/W + 20%

Parent topic: Sizing the metadata servers based on application workload

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