Note that when configuring such disks, use the local PolyServe exposed volume instead of using UNC paths.
Topics | Configure | How To | Troubleshoot | Related Topics
Magnetic Libraries
Overview of Magnetic Libraries
Best Practices for Magnetic Libraries
Shared Magnetic Libraries
Overview of Shared Magnetic Libraries
Magnetic Libraries on Replicated Disks
Overview of Magnetic Libraries on Replicated Disks
Common
Administering Magnetic Libraries
A magnetic library is a virtual library associated with one or more mount paths. The magnetic library does not represent a specific hardware entity; it is a software entity that contains a list of mount paths through which data can be sent to a magnetic media.
Magnetic media, whether individual hard disks or RAID arrays, are logically divided into partitions. A partition can include some or all of the total magnetic disk storage space available. Each partition is associated with a file system path called a mount path, through which data is written to and read from.
A magnetic library can be configured by assigning one or more mount paths to it. The storage capacity of a magnetic library is determined by the total storage space in its mount paths.
Note that the maximum size of a volume that can be used as a mount path can be a maximum of 4,096 Terabytes.
Magnetic libraries are supported on clustered file systems such as Global File Systems (GFS), Cluster File Systems (CFS), IBM General Parallel File System (GPFS), and Polyserve File System.
Deduplication configurations that require multiple MediaAgents must use clustered file system storage for magnetic libraries. Clustered file system storage allows configuring multiple MediaAgents to access and share the same data on disk mount paths. This enables all MediaAgents of a storage policy copy using the same deduplication store to have access to data written by other MediaAgents as well.
The following list provides a set of guidelines to help you ensure that the MediaAgent always accesses the mount paths allocated to magnetic libraries:
We recommend the following practices while creating mount paths:
\\<computer name>\<shared directory name>\<optional path>
| The remote computer can belong to the same domain as the MediaAgent from which it is accessed, or to a different domain, provided that a trust has been set up between that domain and the MediaAgents domain. |
If you have defined multiple mount paths for a magnetic library, the system determines the specific path to which data secured by a data protection operation is written.
The maximum number of writers for a magnetic library is used to determine the maximum number of simultaneous data protection operations. Hence this value is linked to the maximum number of data streams that can be established for a storage policy accessing the magnetic library.
Storage Policy data streams are logical channels that connect client data to the media in which data secured by data protection operations are stored. Multiple data streams can be used to parallelize an operation, in order to improve the rate at which data can be written to the media.
The practical limits for establishing data streams in a storage policy accessing a magnetic library is determined by the minimum value established in either the magnetic library or the sum of mount paths in the magnetic library.
The values for writers can be modified from the Magnetic Library Properties and Mount Path Properties dialog box available in the CommCell Console. The values for the maximum number of data streams can be modified from the Storage Policy Properties dialog box also available in the CommCell Console.
Shared magnetic libraries provide the following benefits:
A shared magnetic library supports all the operations supported (except magnetic migration) by a (non-shared) magnetic library.
Two types of shared magnetic libraries can be configured. They are:
The following sections describe each of these configurations in detail.
Magnetic volumes with a built-in Fiber Channel (FC) adaptor are visible over a Storage Area Network (SAN) to multiple MediaAgents. Such a magnetic volume can be configured as a shared magnetic library between multiple MediaAgents.
Shared magnetic volumes are treated as floating volumes and the mount paths to these volumes are automatically mounted by the MediaAgent, whenever it is required. Only one MediaAgent can mount the volume at any given time and use it. Volumes that are used as shared magnetic library should be dedicated to storing the data associated with the shared magnetic library and should not be shared with any other application. This is a requirement as there are possibilities of volume corruption if a given volume is mounted on more than one host at the same time.
Dynamic mount paths can be configured on MediaAgents with Windows operating systems. See MediaAgents - Supported Features, Agents and Devices for information on MediaAgents that support shared magnetic libraries with dynamic mount paths.
Configuring Shared Magnetic Library with Dynamic Mount Paths is a three-step process:
The concept of shared magnetic libraries is expanded further to include volumes that are statically mounted or accessible in a network, such as PolyServe File System, Sistina GFS (Global File systems), NFS mounted volumes or network shares. Such volumes need not be explicitly mounted and can be accessed by multiple MediaAgents at the same time.
See Configure Shared Magnetic Libraries With Static Mount Paths for step-by-step instructions on configuring magnetic libraries with static mount paths.
|
Disks with PolyServe File System can be configured in a Storage Area Network
(SAN) as a shared magnetic library with static mount paths, as illustrated
in the diagram. Note that when configuring such disks, use the local PolyServe exposed volume instead of using UNC paths. |
|
See Also: MediaAgents - Supported Features, Agents and Devices for information on MediaAgents that support shared magnetic libraries with static mount paths
The following sections provide a set of guidelines for the successful implementation of shared magnetic libraries.
For disks that are replicated to another disk in real-time using software/hardware replication tools, the mount paths from both the primary and replicated disks can be configured as a magnetic library. In such a configuration, the data written by the primary MediaAgent will have read-write access while the MediaAgent on the replica will have read-only access. Note that the primary and replica mount paths can be configured on any MediaAgent type (Windows, Solaris, Linux, etc) or with any network or cluster file systems. (CIFS, NTFS, etc.)
The following example illustrates a magnetic library configuration on a replicated disk:
|
In this example MediaAgent 1 is configured to access a magnetic library
on the primary computer, to backup a mission-critical production server,
such as a server with a large database. (This MediaAgent will have read-write
access to the magnetic library on the primary.) The data is replicated to a replica that contains MediaAgent 2. (This MediaAgent will have read access to the magnetic library on the replica.) Note that when the system performs a data protection operation using the MediaAgent on the primary disk, two copies of the data are available as soon as the disk is replicated. Thus MediaAgent 2 can be used to perform auxiliary copy operations to a tape library, thus limiting the load on the processing capabilities in the production server. Also note that all data protection operations (backup and auxiliary copy) are performed LAN free. Data can be restored from either the primary or replicated disk or from a copy using the tape library. |
 |
See Configure Magnetic Libraries on Replicated Disks for step-by-step- instructions on configuring such libraries.
See MediaAgent Replication solution to seamlessly replicate data from remote offices to centralized data centers using magnetic libraries on replicated disks.
There are several configurable parameters available for Magnetic libraries. The following sections describe each of these parameters.
The system initially assigns a default name for the magnetic library. If necessary, you can modify the name. You can also add relevant information about the library as a description.
This operation is supported by all magnetic libraries.
You can view the MediaAgent name and the number of mount paths associated with each Magnetic library.
This operation is supported by all magnetic libraries.
The status of the magnetic library indicates whether the library is online or offline, and if offline, the reason for the offline status.
You can use the enable/disable indicator to logically enable or disable the magnetic library.
This operation is supported by all magnetic libraries.
See Enable or Disable the Magnetic Library and View the Magnetic Library Offline Reason for step-by-step instructions.
You can establish a low watermark for each magnetic library. The low watermark is the minimum amount of free space at which the low watermark warning should be generated. If the amount of free space, for all the combined mount paths, reaches or falls below the low watermark, the system logs a message in the Event Viewer and generates the Insufficient Storage Alert, if configured. See Establish the Low Watermark for a Magnetic Library for step-by-step instructions.
This operation is supported by all magnetic libraries.
Magnetic volumes are created based on the volume size. When the size of the volume reaches the maximum size, then a new volume is created. The maximum size of a magnetic volume is set to 100 GB by default, and this value can be modified. See Configure the Size of Magnetic Volumes for step-by-step instructions.
This operation is supported by all magnetic libraries.
When this option is enabled, it engages the corresponding read-only lock mechanism on the destination disk system and saves the archive/backup files as read-only files. The expiration date for the read-only lock is set to match the data retention time established in the storage policy copies. These archive files cannot be modified or deleted by any user or application until the specified retention date. Once the retention expires, the system deletes the archives as a part of Data Aging.
This feature is supported on the following disk systems:
This option will only affect files that are subsequently created by data protection and auxiliary copy operations to this library. Permission to files that are already available in this library will not be affected.
See Create Read-Only Archive Files on Disk Systems for step-by-step instructions.
The timeout parameter determines how long a job waits for a status response after an operation is requested. If the job does not receive a success or failure status within the timeout period, the job is terminated and a failure message is displayed. You can set the following timeout periods:
The number of minutes used to mount the magnetic library for read/write operations.
The number of minutes used to unmount the magnetic library after a read/write operation.
See Modify the Mount and Unmount Timeouts for Magnetic Libraries for step-by-step instructions.
This operation is supported by all magnetic libraries.
For appliances that support hardware single instancing of data (e.g., Centera) you can enable the option to write the data in a single instancing format.
See Enable Single Instancing of Data on a Magnetic Library for step-by-step instructions.
This feature requires a Feature License to be available in the CommServe® Server.
Review general license requirements included in License Administration. Also, View All Licenses provides step-by-step instructions on how to view the license information.
The following Agents support this feature:
Agent |
What is Deduplicated |
| Windows File System iDataAgent | Files (Meta-data associated with files are not deduplicated.)* |
| Unix File System iDataAgents | Files |
| Macintosh File System iDataAgent | Files |
| NetWare File System iDataAgent | Files |
| Exchange Mailbox iDataAgent | Attachments |
| Exchange Mailbox Archiver | Attachments |
| Exchange Compliance Archiver | Attachments |
| SharePoint Document iDataAgent | Documents (Meta-data associated with documents are not deduplicated.)* |
| File Archiver for Windows | Files (Meta-data associated with files are not deduplicated.)* |
| File Archiver for Unix | Files |
*Metadata includes Access Control Lists (ACLs) and any additional streams associated with the files.
The following operations are not supported:
| Once you have valid data in the library, you will not be able to change the deduplication status for the library, whether the option is enabled or not. |
See Enable Single Instancing of Data on a Magnetic Library for step-by-step instructions.
These parameters may be used to specify how the system must perform write operations on magnetic libraries with multiple mount paths. Two parameters for mount path usage can be configured. They are:
If this option is selected the system completely fills the disk space (based on the space allocation established for the individual mount paths) before writing to another mount path. Use this option when you want the data to be consolidated, without any fragmentation.
The system will use the mount path in the order in which the mount path was added to the library. For example, a magnetic library has 3 mount paths (A, B, C) configured. All the jobs will be directed to mount path A as it was created first. Mount paths B and C will be used for additional writers in the order in which they were added to the magnetic library. Note that as long as a active volume exists in any of the mount paths, the consecutive backups will continue to use that mount path.
If this option is selected the system writes to all the mount paths in parallel if you have established sufficient number of writers. Use this option to obtain maximum throughput , especially when you have several mount paths. However the data will be fragmented between the available mount paths.
Note that when this option is selected, the system will use the Least Recently Used (LRU) mount path. (As opposed to the mount path with least used capacity.)
For example, a magnetic library with 3 mount paths (A, B, C) and if two 3-stream storage policies (SP_1_1, 2 and 3 and SP_2_1, 2 and 3) are used for running simultaneous backups, the jobs are run as follows: (Assuming that the backups are run for the first time.)
SP_1_1 > Mount Path A
SP_2_1 > Mount Path B
SP_1_2 > Mount Path C
SP_2_2 > Mount Path A
SP_1_3 > Mount Path B
SP_2_3 > Mount Path C
Note that this order may change subsequently, depending on the LRU condition of the mount path.
To illustrate the usage of the above mentioned options, consider the following example:
Assume that a magnetic library that allows multiple writes is configured with two mount paths. Start two jobs - the jobs may either be run concurrently, or individually, one after another. If the Fill and Spill mount paths option is selected, both jobs will use the first mount path. If the Spill and Fill mount paths option is selected, the first job will use the first mount path and the second will use the second mount path.
Note that data protection operations will continue with an available mount path if a required mount path is not available, thereby taking precedence over the option specified for mount path usage. For example, assume that that there are two mount paths, with the Spill and Fill mount path option selected. If one of the mount paths is not available, all data protection operations will use the available mount path.
See Establish the Mount Path Usage for a Magnetic Library for step-by-step instructions.
This operation is supported by all magnetic libraries.
Magnetic disks offer the best choice of media type for fast data protection and recovery operations. Magnetic disks are often used to spool the data before it is archived to tape for long term and/or offsite storage. Using Managed Disk Space data on magnetic disks can be retained as long as possible without running out of disk capacity and affecting future data protection operations. Managed Disk Space provides a way to prune data according to disk capacity in addition to the existing retention criteria which is usually defined by number of days as well as full cycles of data. This adds another layer of retention parameter in addition to specified days/cycles.
Two disk capacity thresholds for managed disk space can be defined. They are:
When disk capacity reaches a high threshold, e.g., 85%, older data automatically qualify for removal. They are removed from the disk if they meet their retention criteria and have been copied to appropriate secondary copies. The aging process automatically stops when the disk capacity reaches a low threshold, e.g., 70%.
Once the managed disk is set up the process runs automatically without user intervention to manage disk capacity. Data protection operations are retained on disk longer than usual providing the benefits of magnetic storage without having to spend manual efforts to manage the disk capacity.
The Enable Managed Disk Space for magnetic data option is available in the Retention tab of the Copy Properties dialog box. If a storage policy is created with a valid retention criteria other than infinite retention, then this option is automatically enabled in the copies.
The pre-defined thresholds for disk capacity for a magnetic library can be defined in the Mount Paths tab of the Library Properties (associated with a magnetic library) dialog box.
Data Aging determines the pruning based on jobs - jobs with older data (based on the creation time of its first archive file) is pruned first. Once the Data Aging operation determines the jobs to be pruned, data will be deleted based on the established threshold. The frequency for checking the disk space and deleting data is determined by the frequency established in the Interval (Minutes) between magnetic space updates option established in the Service Configuration tab of the Media Management Configuration dialog box in the Control Panel.
See Enable Managed Disk Space for Magnetic Data for step-by-step instructions.
See Data Aging for comprehensive information on data aging.
This operation is supported by all magnetic libraries.
The maximum number of writers for a magnetic library is used to determine the maximum number of simultaneous data protection operations. Hence this value is linked to the maximum number of data streams that can be established for a storage policy accessing the magnetic library.
Storage Policy data streams are logical channels that connect client data to the media in which data secured by data protection operations are stored. Multiple data streams can be used to parallelize an operation, in order to improve the rate at which data can be written to the media.
The practical limits for establishing data streams in a storage policy accessing a magnetic library is determined by the minimum value established in either the magnetic library or the sum of mount paths in the magnetic library.
The values for writers can be modified from the Magnetic Library Properties and Mount Path Properties dialog box available in the CommCell Console. The values for the maximum number of data streams can be modified from the Storage Policy Properties dialog box also available in the CommCell Console. See Establish the Mount Path Allocation Policy for a Magnetic Library for step-by-step instructions.
See Establish the Mount Path Allocation Policy for a Magnetic Library for step-by-step instructions.
This operation is supported by all magnetic libraries.
You can view the list of Storage Policies and the Storage Policy Copies accessing the magnetic library. See View a List of Storage Policies Accessing the Magnetic Library for step-step instructions.
This operation is supported by all magnetic libraries.
Security allows you to associate the Magnetic library with one or more CommCell user groups. See User Administration and Security for a detailed explanation on user security.
This operation is supported by all magnetic libraries.
You can migrate a magnetic library to another MediaAgent within the CommCell. Consider the following while performing this operation:
See Migrate a Magnetic Library for step-by-step instructions.
Fragmentation levels in the magnetic mount paths can be analyzed using the Magnetic Library Maintenance administrative job. When executed, the files in the selected mount paths are analyzed and the fragmentation statistics are reported in the Library and Drive Report. Based on the file fragmentation statistics reported, appropriate tools can be used to defragment the magnetic library.
Before using this feature, set the desired fragmentation margin using the following two parameters in the Media Management Configuration (Service Configuration) tab:
The fragmentation threshold percentage is calculated using the following formula:
(Total number of excess fragments)/(Per File Fragmentation Threshold*total number of files) * 100
See Magnetic library Maintenance for step-by-step instructions. The results of the magnetic library maintenance job can be viewed from the Magnetic library Maintenance Job Summary Report.
This feature is supported on Windows MediaAgents. Note that this feature is not supported on Centera Clusters.
Fragmentation levels in the mount path can be reduced by using configuration options. See Reduce Fragmentation of Data on a Mount Path for more information.
From the CommCell Browser, you can perform the following operations on a mount path:
You can view the mount path location and information on the free space available on the mount path and the total amount of valid data. If necessary you can record pertinent information about the mount path as a description in the mount path properties.
This operation is supported by all magnetic libraries.
To increase the speed of operations accessing the mount path, you can enable the MediaAgent to bypass the Microsoft Windows file system buffering. Note that this option is only applicable for Windows MediaAgents and disks that are directly mounted (not UNC paths. (See Enable Unbuffered I/O on a Mount Path or step-by step instructions on enabling this option.)
Note that this is a licensed feature and requires a feature license to be available on the CommServe. However, this option is always enabled for shared magnetic libraries with dynamic mount paths. Therefore additional licenses are not required for this feature on this configuration.
See Enable Unbuffered I/O on a Mount Path for step-by-step instructions.
The mount path can be enabled or disabled, if required, to control the access to the mount path. If the mount path is disabled, it will be displayed as Offline in the General tab of the Mount Path Properties dialog box. If the mount path is disabled by the system due to inaccessibility, the offline reason can also viewed from the General tab of the Mount Path Properties dialog box. Note that when a MediaAgent itself is offline, the individual mount paths are not displayed as offline.
See Enable or Disable a Mount Path for step-by-step instructions.
This operation is supported by all magnetic libraries.
The mount path allocation policy allows you to establish the maximum number of concurrent writers or the maximum number of simultaneous data protection operations on the mount path. See Establish the Mount Path Allocation Policy for the Library for a detailed description.
If necessary you can also disable the mount path for write operation. This is useful in situations where you wish to retire or phase-out a mount path. See Retire a Mount Path for step-by-step instructions.
This operation is supported by all magnetic libraries.
Space allocation allows you to establish the maximum amount of space that must be used by the mount path. This can be done by specifying the reserve space and selecting either the Use until the mount path reaches the reserved space or Do not consume more than n GB options.
If you have established the minimum reserve space as 512 MB, and run a 2 streamed data protection operation when the disk space is 515 MB, both the streams will use a minimum of 25 MB before spanning to an alternate mount path. In such a situation the free space will fall below the specified 512 MB.
This could also happen if 2 concurrent single-streamed data protection operation is initiated to the same mount path, using 2 different storage policies.
When a data protection job is initiated, the system checks for the available disk space and verifies whether it is less than the specified maximum space. For example if you have specified 1 GB as the maximum space and if you have used .75 GB, the data protection job will be initiated using the mount path. However, if the size of the data is .5 GB, the system will write the entire data. In such a situation the space consumed will be more than the specified maximum space.
Note that a data protection operation will generally write to the mount path until the minimum reserve space is reached, before spanning to an alternate path.
See Establish Maximum Space Allocation on a Mount Path for step-by-step instructions.
This operation is supported by all magnetic libraries.
You can reduce the fragmentation of data on a mount path by enabling the Reduce fragmentation by growing the backup chunk by n MB option. This will pre-allocate the space on the mount path for a write operations resulting in reduced fragmentation which in turn will speed-up read operations (auxiliary copy, restore operations) from the disk. This option is supported only for Windows MediaAgents. See Reduce Data Fragmentation on a Mount Path for step-by-step instructions.
Fragmentation levels in the mount path can be analyzed using magnetic library maintenance. See Magnetic Library Maintenance for more information.
You can view the contents of a specific mount path. This feature can be used to view a list of data protection operations residing in the mount path. All the details associated with the data protection operation(s) available in the media are displayed. This includes the following:
See View the Contents of a Mount Path for step-by-step instructions.
This operation is supported by all magnetic libraries.
The delete contents option can be used to logically delete the contents of a mount path.
This operation deletes the data from the CommServe database. Note that this operation does not free-up the disk space in the mount path. A Data Aging operation must be run subsequently to free-up the disk space.
This option can be used to make media available to complete an important data protection job when there is no free-space available in the library.
|
CAUTION Extreme caution should be exercised while using this option as once deleted, the contents of the mount path will not be available for data recovery operations. |
The Delete Contents operation is recorded in the Audit Trail.
See Delete the Contents of a Mount Path for step-by-step instructions.
This operation is supported by all magnetic libraries.
You can protect your mount path contents from being accidentally deleted outside of the CommCell Console. To enable this feature, create the RevokeDeletePermissions registry key on the MediaAgent computer and set the value to 1. This key must be created before configuring the mount path to protect the entire mount path from accidental deletion.
This feature applies to mount paths created on NTFS volumes. This feature is not supported on libraries attached to BlueArc NAS NDMP filers.
There are two ways to move the mount paths to another location:
You can also attach the magnetic library to another MediaAgent by migrating a magnetic library. See Migrate a Magnetic Library for step-by-step instructions.
You can also view or modify the following mount path properties for dynamic mount paths:
See View or Modify the Properties of Shared Disk Devices for a Dynamic Mount Path for step-by-step instructions.
You can view or modify the device alias name and can enable or disable the device. See View or Modify the Device Properties for Magnetic Libraries with Static Mount Paths for step-by step instructions.
You can also view and modify the following properties associated with device paths associated with shared disk devices from a mount path:
See View or Modify the Properties of Disk Devices in a Shared Mount Path for step-by-step instructions.
This operation is supported by all shared magnetic libraries, which includes magnetic libraries on static shares, dynamic shares and replicated disks.
See View or Modify the Properties of Disk Devices in a Shared Mount Path for step-by-step instructions.
Operations performed with this feature are recorded in the Audit Trail. See Audit Trail for more information.
This feature requires a Feature License to be available in the CommServe® Server.
Review general license requirements included in License Administration. Also, View All Licenses provides step-by-step instructions on how to view the license information.
The CV_MAGNETIC folder (which is created when a mount path is configured) will by default be excluded from data protection operations if a MediaAgent and the Windows File System iDataAgent is installed in a computer. (The CV_MAGNETIC folder must be associated with the MediaAgent that is installed in the computer.) To include the folder in data protection operations, the nDoNotFilterGalaxyMagneticMountPaths registry key must be created in the computer.
For more information on using chunk and block sizes, see Performance Tunables for Media Management.
The following Media Management Library Management alerts can be configured from the Alerts Wizard:
For more information, see: