Archive:Media pools 4.4

Media pools

A media pool is a group of media of the same type that you use for backups. You may have different kind of media pools for different types of backup data, backup sources (e.g., file backup, DB backup) or drive types. SEP sesam requires that media pools are configured and media are added to it.

SEP sesam automatically labels each medium with a unique media label during initialization. Media labels are stored in the SEP sesam database. The media label is a combination of the name of the pool (e.g., DAY_, WEEK_, MONTH_) and a 5-digit number. For example, if the name of the pool is LTO_month, the media label for media in this pool consists of a prefix LTO_month, followed by an incrementing number, e.g., 00001 – first media label would be LTO_month00001. The next medium would have a media label LTO_month00002, and so on.

While media pools represent a conventional way of organizing data storage and are typically used for backing up directly to tapes, SEP sesam uses a data store for backing up to disks. Even though the data is still primarily backed up to a media pool, a data store is used underneath to save data directly on one or several configured storage locations – into the file system. The data store space is managed at partition level. For details, see Data Stores.

Media pools are the base for building a backup strategy. Each media pool stands for a set of media, foreseen for a specific purpose. For example, media pools can be created and managed for work days, weekends, certain locations, certain types, databases and more.

Properties

You can create a new media pool from Main Selection -> Media Pools -> New Media Pool. You specify media pool characteristics when configuring a media pool. Some of the properties can subsequently be modified. For details, see Configuring a Media Pool.

Media Pool

Name

The user-defined name of a media pool. The name may not end with five numbers because this form is used for media labeling.

Description

Optional user comment.

Drive Group

Selection of a drive group to which the media pool is attached.

Retention time [Days]

The time period for which all media in the respective media pool are protected after data is written to the medium, thus preserving the save sets and keeping them available for restore. The retention time period starts with the date a save set is written to the media and lasts for the period defined by media pool's EOL (in days).

Readability Check

This is a process that checks the backup data readability. During the check the data on medium is read in blocks, and the structure of tape is checked and recorded. It also checks whether all determined backup sets on the tape are recorded in the database and vice versa. The results are shown in the log.

Readability check is configured by a special media event. For details, see Creating a Media Event.

Readability check limit [days]

By default, the value is 0 (zero) and the readability check is switched off. If a number > 0 is set, a medium is checked after the specified number of days and marked by status Read check required. Readability check can only be applied if a medium EOL has not expired and is not applicable for EOL-free media. For details on EOL, see Media Strategy.

Expiration of read check overdue [days]

The number of days a readability test is overdue. It is calculated based on the readability check limit and the value of expiration overdue.

Repeat rate for readability check [times]

If Unlimited is selected, the medium is checked according to the specified frequency. If Execute is selected, the check will be repeated as many times as specified.

	Note
	To perform the readability check, you have to set up a schedule and link a media event to it. For details, see Creating a Media Event.

Options

You can configure a special set of options to allow sharing of media across media pools.

may use empty, foreign media

If there is no available media in the respective pool and this option is selected, SEP sesam will use unknown or blank media for backup.

may use EOL free media

If selected, media with expired EOL from the same media pool can be used for backup. If not, the use of the specific medium can be forced.

may use SPARE media

If there is no available media in the respective pool, but the media pool SPARE_ is configured and this option is selected, SEP sesam allocates media from the spare pool – the spare medium is removed from the spare pool and added to the target pool.

may use media from another pool

If selected, it allows the respective media pool to use available tapes of other media pools in case it run out of its own.

another media pool may use media from this pool

If selected, another media pool that run out of its own tapes can use the available tapes of this media pool.

	Note
	Media sharing strategies are based on the acquisition of media from the different pools, which means that such media are transferred from the original to the respective pool, and are no longer available in the source pool. You should be aware of this when planning your media strategy.