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- Configure the tape library cleaning method to use. Software cleaning (Commvault) or hardware cleaning (library) can be used, but not both. A choice must be made.
- Share the tape library if required.
- Create a barcode pattern for cleaning tapes and assign it to the Cleaning Media group.
- If using multiple scratch media groups, create scratch groups and barcode patterns to use.
- Validate drive speed (from the CommCell Console) and document for future reference.
Tape libraries are divided into the following components:
- Library – is the logical representation of a library within a CommCell® environment. A library can be dedicated to a MediaAgent or shared between multiple MediaAgents. Sharing of removable media libraries can be static or dynamic depending on the library type and the network connection method between the MediaAgents and the library.
- Master drive pool – is a physical representation of drives of the same technology within a library. An example of master drive pools would be a tape library with different drive types like LTO4 and LTO5 drives within the same library.
- Drive pool – is used to logically divide drives within a library. The drives can then be assigned to protect different jobs.
- Scratch pool – is defined to manage scratch media, also referred to as spare media, which can then be assigned to different data protection jobs.
- Custom scratch pools – can be defined and media can be assigned to each pool.
- Custom barcode patterns – can be defined to automatically assign specific media to different scratch pools or media can manually be moved between scratch pools in the library.
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Commvault software supports the drives for tape libraries:
- Standalone
- Blind
- Dedicated
- Static Shared
- Dynamic Shared
- Virtual Tape Library (VTL)
- USB Devices
Standalone
A standalone tape drive has no robotic media changer and no internal storage slots. Multiple standalone drives controlled by the same MediaAgent can be pooled together to support multi-stream jobs or cascade of a single stream job without having to respond to media handling requests. Media used by a Standalone library can be pre-stamped or new, and will be prompted for, by backup or restore jobs as necessary.
Blind
A 'blind' library has no barcode reader and is supported by the Commvault® software maintaining the map/inventory externally in the CommServe® server metadata.
Dedicated
A static configuration where the drives and media changer are connected to only one MediaAgent.
Static Shared
A static configuration where the drives and media changer are connected to only one of several MediaAgent hosts.
Example: In a library with four tape drives, one MediaAgent may have control of the media changer and two drives within the library while another MediaAgent may have control over the other two tape drives. A drive connected to one MediaAgent host is not accessible from the other MediaAgent hosts. Should the MediaAgent component having media changer control fail, no further loading/unloading of media can occur until that MediaAgent is active again. Shared libraries in today's world of Storage Area Networks (SAN) are not common.
Dynamic Shared
In a Dynamic Shared Library, the library drives and media changer are on a SAN and can be accessed by multiple MediaAgent hosts. Drives not being used by one MediaAgent can be assigned to and used by another MediaAgent. If the MediaAgent with control of the media changer fails, the control can be automatically passed to another MediaAgent. The primary advantage of a Dynamic Drive library is the use of multiple MediaAgents for processing reads/writes. Dynamic Drive capability is referred to as GridStor® Technology. GridStor technology is an option that enables load balancing and failover of data protection jobs.
Virtual Tape Library (VTL)
A Virtual Tape Library (VTL) is a disk-based library that emulates the traditional tape devices and formats, and can be installed onto any disk space. Refer to the manufacturer's documentation to see if a disk-based storage subsystem supports VTL emulation mode. Follow the manufacturer's instructions to create the virtual tape library and make sure that the MediaAgent can detect the virtual arm changer and the drives created.
USB Devices - PnP (Plug and Play) Disk Libraries
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General Tape Library Configuration Options
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Virtual Mail Slots
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Appendable Media
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Media Container and Export Location Reset
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Auto-Cleaning
Over time when using tape drives, dirt can accumulate on the drive read/write heads. When it happens it's important to clean the drives using a cleaning media. This process is usually automated but can be executed manually.
There are two different methodology when cleaning drives:
- Hardware Controlled Cleaning – The cleaning of the drives is handled by the library itself. In this scenario, auto-cleaning must be disabled in Commvault® software and must be enabled on the library by using either the administration web portal or its control panel. The library configures dedicated cleaning slots where cleaning media are stored. The dedicated cleaning slots and cleaning media are not visible in Commvault software and cannot be used. Manual cleaning operations must be initiated from the library web page.
- Software Controlled Cleaning – The cleaning of drives is handled by Commvault software. In this scenario, auto-cleaning must be disabled on the library and must be enabled in Commvault software. The library does not reserve any dedicated cleaning slots and Commvault software is aware of the cleaning media. Cleaning must be initiated from Commvault® software.
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Overwrite Media Option
There are few media overwrite options that are set when configuring a tape library. These options apply to specific scenarios and should be carefully evaluated before planning on enabling it.
- When content verification fails – If enabled, when the MediaAgent encounters a media that it cannot read, such as a 'bad On Media Label (OML),' it automatically overwrites that tape. This option should be carefully planned as it could result in overwriting valid data.
- When it comes from a different CommCell environment – By default, when a tape was used in a different CommCell environment, Commvault® software does not use the media and moves them into a media group called 'Foreign Media'. If desired, the media can automatically be used as scratch tapes by checking this option.
- Prevent use of tapes from a different backup vendor – This option is useful when the library is shared with another backup software. Since every vendor uses different writing format, Commvault software can identify a tape coming from a different vendor and prevent its use by checking that option.
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Media Stuck in Drive
If a media is stuck in a drive for any reason, Commvault® software offers few options to help resolving the situation.
- Enable Auto-Recovery – When this option is enabled, the MediaAgent tries to recover the Media every 20 minutes.
- Attempt to remove media from the drive when unload fails – When this option is enabled and the MediaAgent 'unload' command fails, it tries using a move command instead, which in some cases might successfully move the media out of the drive.
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Unmount Idle Media Timeout
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Partitioned Library Recommended Options
When a tape library is partitioned and shared with another CommCell® environment or another backup software, some options should be considered and could be beneficial as it ensures that the media are imported in the proper library partition.
- Do Periodic mail slot check for any change in status – This option periodically polls the library every 30 seconds for any change in the I/E ports status. The frequency of the polling is configured using the 'Library Status Check Interval' option.
- Prevent Auto Import of Media from mail slot – This option, when checked, prevents the MediaAgent from importing the media automatically when inserted in the mail slots. The import must be manually launched from the CommCell® console.
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Tape Library Associated Storage Policies
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Drive Validation
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Replacing a defective drive has an impact on backup software. Tape drives are mapped to their serial number in Commvault® software. Some drive models now allow the serial number of the drive to be configured, which alleviates any impact on the backup system. But if the drive is not replaced with the same serial number, it must be addressed in Commvault software.
When the drive is replaced, right-click the old drive and choose 'Mark Drive Replaced.' After a few minutes, the system re-maps the drive to the new serial number and the drive becomes available. It is also possible to configure the system to attempt to remap replaced drives automatically. This is accomplished by enabling the automatic drive replacement in the library properties.
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Cloud storage is an emerging technology that is quickly being integrated into data centers for its availability and, in some cases, lower Total Cost of Ownership (TCO). As a DR solution, however, there are still significant questions on its effectiveness. The two biggest questions regarding cloud storage for DR are bandwidth availability and data security. Using advanced features such as Commvault deduplication can greatly reduce the bandwidth requirements of backing up to cloud storage. However, in a disaster situation where a significant amount of data must be restored, bandwidth can become a serious bottleneck.
Data transfers are achieved using secured channels (HTTPS) and are optionally encrypted to further secure the data sent to the cloud.
Cloud libraries best practices:
- Properly plan and analyze if the cloud library scenario meets the needs (i.e. restoring an entire datacenter).
- If the link is shared with users, consider throttling Commvault® bandwidth usage during business hours.
- If the MediaAgent does not have direct access to the internet, define the proxy settings in the Advanced tab of the cloud library configuration page.
- If the cloud library is accessed through a high-speed internet link (1GB or higher), consider tuning the connection. For more information, refer to the Commvault Online Documentation, 'Cloud Connection Performance Tuning' section.
- If using deduplication, by default, jobs are not aged and pruned unless the DDB is sealed. If you want to age and prune jobs as soon as retention is met, configure micro pruning. For more information, refer to the Commvault Online Documentation, 'Configuring Micro Pruning on Cloud Storage' section.
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