How to estimate or calculate Tivoli Storage Manager TSM database size

How to estimate or calculate Tivoli Storage Manager TSM database size

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To estimate space requirements for the database, you can use the maximum number of files that can be in server storage at one time or you can use storage pool capacity.

Estimating Tivoli Storage Manager database size

Consider using at least 25 GB for the initial database space. Provision file system space appropriately. A database size of 25 GB is adequate for a test environment or a library-manager-only environment. For a production server supporting client workloads, the database size is expected to be larger. If you use random-access disk (DISK) storage pools, more database and log storage space is needed than for sequential-access storage pools. 

The maximum size of the Tivoli Storage Manager database is 4 TB. For estimating Database consider the following example.

Estimating database space requirements based on the number of files

If you can estimate the maximum number of files that might be in server storage at a time, you can use that number to estimate space requirements for the database.
To estimate space requirements for the database based on the maximum number of files in server storage, use the following guidelines:
  • 600 - 1000 bytes for each stored version of a file.
  • 100 - 200 bytes for each cached file, copy storage pool file, active-data pool file, and deduplicated file.
  • Additional space is required for database optimization to support varying data-access patterns and to support server back-end processing of the data. The amount of additional space is equal to 50% of the estimate for the total number of bytes for file objects.
Also Read: How to increase or decrease TSM DB, active log and archive log size ?
In the following example for a single client, the calculations are based on the maximum values in the preceding guidelines. The calculations do not take into account the possible use of file aggregation. In general, aggregating small files reduces the amount of required database space. File aggregation does not affect space-managed files.
  1. Calculate the number of file versions:
    1. Calculate the number of backed-up files: As many as 500,000 client files might be backed up at a time. Storage policies call for keeping up to three copies of backed up files: 
      500,000 files x 3 copies = 1,500,000 files
    2. Calculate the number of archive files. As many as 100,000 client files might be archived copies.
    3. Calculate the number of space-managed files. As many as 200,000 client files might be migrated from client workstations.
    Using 1000 bytes per file, the total amount of database space required for the files that belong to the client is 1.8 GB: 
    (1,500,000 + 100,000 + 200,000) x 1000 = 1.8 GB
  2. Calculate the number of cached files, copy storage-pool files, active-data pool files, and deduplicated files.
    1. Calculate the number of cached copies. Caching is enabled in a 5 GB disk storage pool. The high and low migration thresholds of the pool are 90% and 70%. Thus, 20% of the disk pool, or 1 GB, is occupied by cached files.
      If the average file size is about 10 KB, approximately 100,000 files are in cache at any one time: 
      100,000 files x 200 bytes = 19 MB
    2. Calculate the number of copy storage-pool files. All primary storage pools are backed up to the copy storage pool: 
      (1,500,000 + 100,000 + 200,000) x 200 bytes = 343 MB
    3. Calculate the number of active storage-pool files. All the active client-backup data in primary storage pools is copied to the active-data storage pool. Assume that 500,000 versions of the 1,500,000 backup files in the primary storage pool are active: 
      500,000 x 200 bytes = 95 MB
    4. Calculate the number of deduplicated files. Assume that a deduplicated storage pool contains 50,000 files:
      50,000 x 200 bytes = 10 MB
    Based on the preceding calculations, about 0.5 GB of additional database space is required for the client’s cached files, copy storage-pool files, and active-data pool files, and deduplicated files.
  3. Calculate the amount of additional space that is required for database optimization. To provide optimal data access and management by the server, additional database space is required. The amount of additional database space is equal to 50% of the total space requirements for file objects.
  4. (1.8 + 0.5) x 50% = 1.2 GB
  5. Calculate the total amount of database space that is required for the client. The total is approximately 3.5 GB: 
    1.8 + 0.5 + 1.2 = 3.5 GB
  6. Calculate the total amount of database space that is required for all clients. If the client that was used in the preceding calculations is typical and you have 500 clients, for example, you can use the following calculation to estimate the total amount of database space required for all clients:
    500 x 3.5 = 1.7 TB
In the preceding examples, the results are estimates. The actual size of the database might differ from the estimate because of factors such as the number of directories and the length of the path and file names. Periodically monitor your database and adjust its size as necessary.

During normal operations, the Tivoli® Storage Manager server might require temporary database space. This space is needed for the following reasons:
  • To hold the results of sorting or ordering that are not already being kept and optimized in the database directly. The results are temporarily held in the database for processing.
  • To give administrative access to the database through one of the following methods:
    • A DB2® open database connectivity (ODBC) client
    • An Oracle Java™ database connectivity (JDBC) client
    • Structured Query Language (SQL) to the server from an administrative-client command line
Consider using an additional 50 GB of temporary space for every 500 GB of space for file objects and optimization. See the guidelines in the following table. In the example used in this topic, a total of 1.7 TB of database space is required for file objects and optimization for 500 clients. Based on that calculation, 200 GB is required for temporary space. The total amount of required database space is 1.9 TB.

Database size Minimum temporary-space requirement
< 500 GB 50 GB
≥ 500 GB and < 1 TB 100 GB
≥ 1 TB and < 1.5 TB 150 GB
≥ 1.5 and < 2 TB 200 GB
≥ 2 and < 3 TB 250 - 300 GB
≥ 3 and < 4 TB 350 - 400 GB

Estimating database space requirements based on storage pool capacity

To estimate database space requirements based on storage pool capacity, use a ratio of 1 - 5%. For example, if you require 200 TB of storage pool capacity, the size of your database is expected to be 2 - 10 TB. As a general rule, make your database as large as possible to prevent running out of space. If you run out of database space, server operations and client-store operations can fail.

Database space required when running database operations

The database manager of the Tivoli® Storage Manager server manages and allocates system memory and disk space for the database. The amount of database space that the system requires depends on the amount of system memory that is available and the server workload. 

For example, expiration processing can use a large amount of database space. If there is not enough system memory in the database to store the files identified for expiration, some of the data is allocated to temporary disk space. During expiration processing, if a node or file space is selected that is too large to process, the database manager cannot sort the data.

To run database operations, consider adding more database space for the following scenarios:
  • The database has a small amount of space and the server operation that requires temporary space uses the remaining free space.
  • The file spaces are large, or the file spaces have a policy assigned to it that creates many file versions.
  • The Tivoli Storage Manager server must run with limited memory.
  • An out of database space error is displayed when you deploy a Tivoli Storage Manager V6 server.
Do not alter the DB2 software that is installed with IBM® Tivoli Monitoring for Tivoli Storage Manager installation packages and fix packs. Do not install or upgrade to a different version, release, or fix pack of DB2 software because doing so can damage the database.

The database manager and temporary space

The Tivoli Storage Manager server database manager manages and allocates system memory and disk space for the database. The amount of database space you require depends on the amount of system memory available and the server workload. 

 Also Read: TSM Storage Pool Concepts (V7 Revised)

The database manager sorts data in a specific sequence, as per the SQL statement that you issue to request the data. Depending on the workload on the server, and if there is more data than the database manager can manage, the data (that is ordered in sequence) is allocated to temporary disk space. Data is allocated to temporary disk space when there is a large result set. The database manager dynamically manages the memory used when data is allocated to temporary disk space.

For example, expiration processing can produce a large result set. If there is not enough system memory on the database to store the result set, some of the data is allocated to temporary disk space. During expiration processing, if a node or file space are selected that are too large to process, the database manager does not have enough memory to sort the data.

To run database operations, consider adding more database space for the following scenarios:
  • The database has a small amount of space and the server operation that requires temporary space uses the remaining free space.
  • The file spaces are large, or the file spaces has a policy assigned to it which creates many file versions.
  • The Tivoli Storage Manager server must run with limited memory. The database uses the Tivoli Storage Manager server main memory to run database operations. However, if there is insufficient memory available, the Tivoli Storage Manager server allocates temporary space on disk to the database. For example, if 10G of memory is available and database operations require 12G of memory, the database uses temporary space.
  • An out of database space error is displayed when you deploy a Tivoli Storage Manager V6 server. Monitor the server activity log for messages related to database space.

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