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Expanding Spectrum Protect Server Database on Different Type of Storage Technology

Question & Answer


Question

Is it applicable to use SAS disks to expand a Spectrum Protect Server database that is located on SSD disks?

and how? 

Answer

Typically, hardware configuration and selection have the most significant effect on the performance of a Spectrum Protect solution. Storage devices have different capacity and performance characteristics. These characteristics affect which devices are better for use with the server database.

The IBM Spectrum Protect Blueprints provide documentation on hardware and software requirements and automated scripts to configure small, medium, and large server architectures. This information is intended to facilitate the deployment of an IBM Spectrum Protect server by using detailed hardware specifications to build a system and automated scripts to configure the software.

We always recommend using fast, low-latency disks. Using SSD is essential if you are using data deduplication and node replication. Avoid Serial Advanced Technology Attachment (SATA), Parallel Advanced Technology Attachment (PATA) disks, Nearline SAS (NL-SAS), and internal disks that are included by default in most server hardware.

Expanding the server database space on SAS disks is applicable as the operating system abstracts that underlying block device type. However, it is not preferable as it will defeat performance advantages of the used SSD disks such as ( Heat, Access time, Power, …).

For more details and more tips on choosing the correct type of storage technology for the server database, see the following checklist:

Increasing space for the database by adding directories for the database to use, you can create new directories and add them by two methods.

By default, these commands will allow the data to be redistributed across the new database directories and storage space in the old directories is reclaimed. This action makes the new directories available for use immediately.

You should make sure that sufficient disk space is available for the operation and the new directories are empty. The process of redistributing data and reclaiming space uses considerable resources. However, if you do not want to redistribute data at the same time that you add directories, you can set the RECLAIMSTORAGE parameter in the EXTEND DBSPACE command to 'No'. You can perform the tasks to redistribute data and reclaim space after the database size is increased. however, at that time the steps must be done manually.

  • Steps to add extra space when the server is up and running:

To add the extra space when the server is online, use the EXTEND DBSPACE command. The redistribution process as part of an operation to extend database space uses considerable system resources, so ensure that you plan ahead for the process when the server is not handling a heavy workload.

Do not interrupt the redistribution process. If you try to stop it, for example, by halting the process that is completing the work, you must stop and restart the server instance. When the server is restarted, it will go into crash recovery mode, which takes several minutes, after which the redistribution process resumes.

- Create one or more directories for the database on separate drives or file systems. How you spread the database directories across available disk storage has a strong effect on performance. Make all directories that are used for the database the same size to ensure parallelism. For most disk systems, performance is best if one database directory is on one LUN, which has one logical volume. Aim for a ratio of one database directory, array, or LUN for each inventory expiration process.
- Make sure that there are no heavy background processes are running such as reclamation and expiration etc.
- Then issue the EXTEND DBSPACE command to add the directory or directories to the database. The directories must be accessible to the user ID of the database manager.
By default, data is redistributed across all database directories, and space is reclaimed.
For example:
extend dbspace db_new_directory
To increase the size of the database without redistributing data and reclaiming space, issue the following command:
extend dbspace db_new_directory reclaim=no

The time that is needed to complete redistribution of data and reclaiming of space is variable, depending on the size of your database. Make sure that you plan adequately.

Note: You can Halt and restart the server or you might not need to restart the server to fully use the new directories. If the existing database directories are nearly full when a new directory is added, the server might encounter an out of space condition reported in the db2diag.log. This condition should be corrected by halting and restarting the server.

  • Steps to add extra space when the server is offline:

Use DSMSERV EXTEND DBSPACE utility to add the extra space when the server is offline. This utility performs the same function as the EXTEND DBSPACE command, but you can use it when the server is not running.

- Create one or more directories for the database on separate drives or file systems. The directories must be accessible to the user ID of the database manager.
- Go to the instance directory and issue the DSMSERV EXTEND DBSPACE command to increase the database size. You can also specify whether data is redistributed across newly created database directories and space is reclaimed from the old storage paths when you add space to the database. This parameter is optional and the default value is 'Yes'. The redistribution process uses considerable system resources so ensure that you plan adequately. Also, the server might be offline for a while, until the process is completed, however, it is recommended to leave it as default to get optimal DB performance.
For example:
dsmserv extend dbspace db_new_directory
- Restart the server instance and check the DB size by issuing QUERY DBSPACE command.

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Historical Number

TS003098140

Product Synonym

TSM;SP

Document Information

Modified date:
15 May 2020

UID

ibm11166566

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