Sizing the metadata servers based on application workload

This topic helps you determine the number of metadata servers that are needed to handle the workload based on the application workload.

Context

It is importance to understand the right parameters for loading and sizing the SAN File System to help determine how many metadata servers are needed for a given client workload. Important factors to consider are:
  • Number and the mix of file system objects, such as files, directories and symbolic links that would be involved in the combined workload as seen by the Metadata server cluster, and how many filesets those file system objects are partitioned into.
  • Size and mix of the hotset of those objects and filesets that each client would expect to operate upon with their respective applications.
  • Typical file operations that a client application might generate. This exercise requires expertise with the application under consideration. However, FOPs for many well-known and standard workload classifications can be used to estimate this information.
  • An estimate for the type of caching that the metadata will have for the given application load.

This estimate can be based on the mix of FOPs that the application generates, the hotset of objects and the size of the metadata cache. However, various client installable file systems might have varying amounts of memory that can be used for caching the metadata.

Perform the following steps to size the metadata servers based on application workload and characteristics is based on the following steps:
  1. Understand the type of workload that the application generates. A reference table for a variety of standard workload types has been presented to help map your application to one or more of the standard application types.
  2. Gather specific workload and environment information by answering a set of questions. Because it may be difficult to get answers to all the questions for all the environments, we have divided the questionnaire into mandatory and optional parts.
  3. Calculate the number of file operations that will be generated per second for the specific workload and environment, based on the cache effectiveness measure provided for various workload, and, based on that, calculate the number of metadata server operations that will be generated.
  4. calculate the number of metadata servers required based on the number of metadata server operations generated per second and the sustained rate of transaction serving capacity that you assume for the metadata server.

The next few sections take you through each of the steps in detail.

Use the Metadata servers — application workload method worksheet to help you size the metadata servers.

Parent topic: How many metadata servers do I need?

Related information
Metadata servers — application workload method worksheet

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