Silo Storage provides the ability to store deduplicated data in tapes. This is
performed as follows:
Backup data from clients is first deduplicated in a primary disk.
The deduplicated data, which includes the deduplication store and the data
(called as Silos), are then copied to tape by running a Silo backup job.
During a restore operation, if the data is available in disk it is restored
from the disk. If the data is not available, then the necessary tapes are accessed
to bring back the data to the disk, and then restored to the client.
The following illustration provides an overview of Silo Storage.
To enable Silo Storage in your environment you need to:
Create a Silo enabled Storage Policy copy
Use this storage policy to perform backups from your clients by pointing
the subclients to the Silo enabled storage policy copy
Run or schedule silo job to move the data to Silo storage
This is explained in the Getting Started section. The following sections describe
additional options for managing Silo storage.
Silo backup operations are performed using dedicated data streams to avoid the
job going into a pending state. These dedicated silo streams are in addition to
the data streams configured for the copy.
By default, the system assigns one silo stream per copy. You can add or modify
the number of silo streams for each copy.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
In the Number of Silo streams box, type or select
the number of dedicated data streams you want to change.
Silo backup jobs can be interrupted and stopped when the job is in progress.
This is done by using the Commit option in the Job Controller. When used
it terminates the silo backup job, by committing the data in the Silo storage as
available at that point in time.
The next Silo backup job will automatically start the backup from where the previous
backup ended. For example, if the job had to transfer 10 volumes to Silo Storage
and you chose the Commit operation while transferring volume 6, the first 5 volumes
transferred to Silo storage is committed and the job is successfully completed.
The next backup job to Silo Storage will start from volume 6.
From the CommCell Browser, in the Job Controller window,
right-click the silo backup job and click Commit.
The job status may change to Interrupt Pending for a few
moments while the operation completes.
Once operation completed, the
job status will change to Complete.
When a Silo backup is restored, it follows one of the following two sequences:
If the data is available in the primary disk, it is restored from the primary
disk.
If the data is not available in the primary disk, then the following two
phase restore is performed:
First the original restore operation goes to Pending state in the Job
Controller, and automatically kicks off another job called the Silo Retrieval
job to retrieve data from tape to the primary disk.
Once the data is available in the primary disk, the original restore
operation automatically resumes to restore the data to the restore location.
This two-phase restore is an entirely seamless operation and does not require
user intervention. The Job Controller displays both the original restore as well
as the Silo Retrieval jobs.
The following sections describe how to restore from a silo.
When you perform a restore operation, you must determine whether the data is
available in the disk or in the tape. If the data is available in the tape, you
must recall the media and have it available in the storage device to successfully
complete the restore.
The following steps provides information on how to identify the media:
From the CommCell Browser, navigate to Client Computers |
<Client> | File System | defaultBackupSet.
Right-click the subclient in the right pane and click Browse
Backup Data.
Click OK.
From the browse window, expand the tree and select the files and/or
folders that you wish to restore and then click List Media and Size
button.
Click OK.
The Media dialog box, displays the location of the selected data. This
could be one of the following:
Primary disk
If the data is available in the primary disk, you
can proceed with the restore.
List of tapes
If the data is available in tapes and if the tapes are available
in the storage device (library) you can proceed with the restore.
If the data is available in tapes and if the tapes were removed
for off-site storage then click the Recall Media button.
Restart the restore operation once the requested media is available
in the storage device.
Temporarily Disable Space Management
Use the following steps to disable space management on the disk. This will ensure
sufficient space for silo restores and is useful when restoring large volumes of
data from Silo Storage.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
Clear the Enable Backup of Deduplicated Data check box.
When data from Silo Storage is restored, the Silos are retrieved to the primary
media. By default, the Silos are retrieved to the original mount path from which
the data was migrated to silo storage. However, during a restore, if the original
mount path does not have enough space, the Silos are automatically copied to any
other mount path with sufficient space available in the library.
To ensure that a mount path with sufficient space is available in the library
at all times, you can have a dedicated mount path that is reserved for Silo restore
operations only. When reserved for Silo restores, the number of data writers to
the mount path is set to zero and this prevents the mount path from being used for
regular backup operations.
When a reserved mount path is available, then all Silo restore operations on
the library are run to the mount path by default. It is recommended that the storage
capacity on this mount path is equivalent to the size of an average Silo.
The following steps provides information on how to reserve a mount path for Silo
restores:
From the CommCell Browser, navigate to Storage Resources | Libraries
| <library>.
Right-click the mount path in the right pane and then click Properties.
Select the Reserve Space for SILO Restores check box.
By
default, the Silo restore will be performed on the source MediaAgent which was used
to make the Silo backup. If necessary, you can also select a specific MediaAgent
to perform the Silo restore. This may be needed in some situations as shown in the
diagram.
MediaAgent 1 in a remote office is used to perform deduplicated backup to
disk library which is replicated continuously to a disk library in the Data
Center.
MediaAgent 2 is used to perform a Silo copy of the data.
The resulting media containing the Silo data is moved to the Data Center
for storage.
If you need to restore the data from the Silo volume, you can use MediaAgent
3. If you do not use this option, the restore will start in the source which is
MediaAgent 2.
In the following procedure you can designate MediaAgent 2 as the Source MediaAgent
and MediaAgent 3 as the destination MediaAgent.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
Select source MediaAgent from the Select MediaAgent for Silo
Restores list.
As this MediaAgent will be used to access
the tape library containing the Silo storage media, ensure to
select a MediaAgent that has access to the appropriate storage
media containing the Silo enabled source copy.
Select destination MediaAgent from the Select Destination client
for Silo Restores list, to which the Silo volumes must be restored.
You can perform an Auxiliary Copy of the Silo storage.
This Auxiliary Copy will preserve the data deduplication in the Silo Storage
and can be used to make the additional copies of the data.
The diagram
illustrates the tape-to-tape Auxiliary Copy with Silo Storage.
Use the following steps to setup tape-to-tape auxiliary copy:
From the CommCell Browser, navigate to Policies | Storage
Policies.
Right-click the primary storage policy containing the silo enabled
storage policy copy, and then click Properties.
Click Retention tab, and note down the values specified in
the Basic Retention Rule for All Backups area.
Click OK.
From the CommCell Browser, navigate to Policies | Storage Policies
| <Storage_Policy>.
Right-click <storage_policy>, point to All Tasks and
then click Create New Copy.
Specify name in Copy Name.
From the Library list, click the name of a tape library.
From the MediaAgent list, click the name of a MediaAgent.
From the Drive Pool list, click the name of the drive pool.
From the Scratch Pool list, click the name of the default
scratch.
Click Associations tab.
Clear Client Computers and navigate to Client Computers
| <CommServe_Client> | Windows File System | SILO_BackupSet_<Storage
Policy name>_<Storage Policy Copy name> and then select
default.
Click the Retention tab.
Enter the same data retention values in the Basic Retention Rules
for All Backups area, that you noted in the above steps from primary
copy.
Click OK.
Right-click <storage_policy>, point to All Tasks and
then click Run Auxiliary Copy.
A conventional Auxiliary Copy stores the original data without preserving
the data deduplication. Use the conventional Auxiliary Copy if you wish
to retain a copy of the complete data, without the deduplication.
The conventional Auxiliary Copy is done as follows:
If the data is available in the primary disk, it is unraveled in
the primary disk and copied to tape.
If the data is not available in the primary disk, then the following
two phase Auxiliary Copy operation is performed:
First the original Auxiliary Copy operation goes to Pending
state in the Job Controller, and automatically kicks off another
job called the Silo Retrieval job to retrieve data from tape to
the primary disk.
Once the data is available in the primary disk, it is unraveled
in the primary disk and copied to tape.
To restore data from such copy, set the copy precedence as described
in Restore From A Copy.
Use the following steps to setup a conventional Auxiliary Copy:
From the CommCell Browser, navigate to Policies | Storage
Policies.
Right-click the primary storage policy containing the silo enabled
storage policy copy, and then click Properties.
Click Retention tab, and note down the values specified in
the Basic Retention Rule for All Backups area.
Click OK.
From the CommCell Browser, navigate to Policies | Storage Policies
| <Storage_Policy>.
Right-click <storage_policy>, point to All Tasks and
then click Create New Copy.
Specify name in Copy Name.
From the Library list, click the name of a tape library.
From the MediaAgent list, click the name of a MediaAgent.
From the Drive Pool list, click the name of the drive pool.
From the Scratch Pool list, click the name of the default
scratch.
Click the Retention tab.
Enter the same data retention values in the Basic Retention Rules
for All Backups area, that you noted in the above steps from primary
copy.
Click OK.
Right-click <storage_policy>, point to All Tasks and
then click Run Auxiliary Copy.
You can have a non-silo primary copy to backup data without deduplication and
then enable silo in the secondary copy. The data from the primary copy is deduplicated
on a primary disk and the silo's are then moved to a tape when a silo backup is
run on the secondary copy.
Use the following steps to create a silo enabled secondary copy:
1.
From the CommCell Browser, navigate to Policies |
Storage Policies | <Storage_Policy>.
Right-click <storage_policy>, point to All
Tasks
and then click Create New Copy.
2.
Specify name in Copy Name.
From the Library list, click the name of a disk library.
From the MediaAgent list, click the name of a MediaAgent.
Select Enable Deduplication box. The Deduplication
tab is enabled.
Click Deduplication tab.
Deduplication can only be enabled for
storage policy copies associated with a disk library.
3.
The default name of the deduplication store is displayed in
Deduplication Store Name box.
In the Deduplication Store Access Path area, click
Add.
4.
From the MediaAgent list, click the name of a MediaAgent.
Type the name of the folder in which the deduplication database
must be located in the Deduplication Store Location or click
the Browse button to select the folder.
Click OK.
5.
The store information is displayed in the Deduplication Store
Access Path area.
Click OK.
6.
Click OK to accept the default schedule.
7.
Secondary Copy is displayed in the Storage Policy
pane.
8.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the Secondary storage policy copy displayed in the right
pane and click Properties.
9.
Click the Deduplication tab and then click Silo
Option tab.
10.
Select the Enable Backup of Deduplicated Data check box.
Clear Number of Silos to be kept in cache check box.
Click Add Data Path button.
11.
Click the Tape Library and click OK.
12.
The list of data paths will be displayed.
Click OK.
13.
Click OK to enable the Silo Storage.
14.
From the CommCell Browser, navigate to Client Computers |
<CommServe_Client> | File System.
A Silo Storage Set with SILO_BackupSet_<Storage Policy name>_<Storage
Policy Copy name> naming convention is displayed.
A Silo Storage Set is a special type of On
Demand Backup Set containing Silo Storage data. This set must not
be modified for any type of operation.
By default, a new deduplication store is created for every 100 TB of data. Note
that this is the amount of data stored on the media after deduplication. Depending
upon your configuration and requirement, deduplication store creation can be configured
based on the following parameters:
Create Store every 'n' number of days.
Create Store every 'n' TB.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab.
In the Deduplication Store Creation, select one of the following:
Select Create new store every - days and specify
the number of days after which a new deduplication store must be
created.
Select Create new store every - TB and specify the size
of the store, reaching which a new deduplication store must be created.
If above both options are set, a new
deduplication store will be created if either one of the
two conditions is satisfied.
Select Create new store every - Month(s). Starting from...
and specify the month and start date for a new deduplication store
creation.
An active deduplication store can also be sealed on-demand. If the deduplication
store contains critical data that must be protected for compliance purposes, or
the deduplication store must be moved to Silo Storage immediately to preserve the
data, you can seal the currently open deduplication store on-demand and initiate
a Silo Backup to move the data to Silo Storage. Once the volume is closed, the data
is moved to Silo Storage after 8 hours by default.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane, point to All Tasks and then click Seal Deduplication
Store.
Click Yes on the Confirm Seal Deduplication Store
dialog box.
The current active deduplication store will be sealed and the data will
be moved automatically to Silo Storage after 8 hours.
Silo can be set to automatically archive the deduplication store after you seal
it. Archiving the deduplication store frees up disk space by moving the sealed store
to Silo Storage.
Deduplication store can be Archived as follows:
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab and then click the Silo Options
tab.
A Storage Policy Copy can be configured to use more than one Silo data path.
Use the following steps to setup multiple data paths:
If the data paths are from multiple MediaAgents, then
ensure that the index cache is shared between all the MediaAgents associated
with the Silo data paths as well as the MediaAgent associated with the primary
disk mount path.
All data paths must have read/write permission from all
MediaAgents.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Data Paths tab.
Click Add button to add the multiple data paths.
When using multiple silo data paths, the
data paths are used based on the criteria defined in the
Data Path Configuration tab.
The recently moved silo(s) can be retained in the local cache. This eliminates
the need to restore the data from the Silo Storage to the primary disk.
Use the following steps to configure the number of silos that must be maintained
in the local cache.
The number of silos to be retained corresponds to the
silos that are moved to the silo storage and does not include the ones recalled
during restores. For example, if you set the value to 3, the currently active
Silo and two recently closed Silos would be retained in the local cache.
If you set this value to 0, no silo is retained in the cache.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
In the Number of Silos to be kept in cache box, type or select
the number of dedicated data streams you want to change. The default
value is set to 1.
Silo Storage provides data encryption options during data transmission over networks
and for storage on media. When data is migrate to offsite storage, data encryption
increases the security and integrity of the data.
Use the following steps to enable
data encryption:
From the CommCell Browser, navigate to Client Computers.
Right-click the <CommServe Client> and then click Properties.
Click Encryption tab, and then click the Encrypt Data
check box.
The Pass Phrase is not supported
for encryption on Silo Storage.
Navigate to Client Computers | <CommServe_Client> | File
System | SILO_BackupSet_<Storage Policy name>_<Storage
Policy Copy name>.
Right-click the <subclient> displayed in the right pane and click
Properties.
Data migrated to Silo Storage can be stored in compressed format. Compression
reduces the quantity of data sent to storage, often doubling the effective capacity
of the media (depending on the nature of the data.) This provides the option to
have the data in the primary storage in its original form, and enable data compression
when the data is migrated to Silo Storage.
If hardware compression is enabled, then software compression
is ignored during Silo backups.
From the CommCell Browser, navigate to Client Computers |
<CommServe_Client> | File System | SILO_BackupSet_<Storage
Policy name>_<Storage Policy Copy name>.
Right-click the <subclient> displayed in the right pane and click
Properties.
Click the Storage Device tab and then click the Data Transfer
Option tab.
In Software Compression area, click On MediaAgent.
If the data to be backed up is spread over multiple mount paths having multiple
data streams, then you can use the data multiplexing to combine the streams during
the write operation. Data multiplexing increases the speed of write operations.
This feature is particularly useful in case of high-speed tape drives to fully utilize
the high throughput. See
Data Multiplexing
for a detailed discussion on data multiplexing.
Multiplexing factor is the number of data streams that are backed up concurrently
to the same media. See
Determining the Multiplexing Factor for more information on how to decide the
multiplexing factor.
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
Select the Enable Multiplexing check box.
In the Silo Archive Mux Factor box, type or select the number
of multiplexing factor for silo operations. The default value is set
to 1.
Silo space management provides disk cleanup options to automatically reclaim
the primary disk space once the data is moved to Silo Storage. Disk space occupied
by the deduplication store and the associated deduplicated data can be effectively
managed and reclaimed as follows:
Only data from the disk media that has been moved to Silo Storage is considered
for removal.
The removal of data is based on a LRU (Least Recently Used) algorithm.
The following exceptions apply:
If a Silo is retained in the local disk cache (as described in
Retain Silos in the Local Cache),
it will not be considered for removal.
If the Storage Policy Copy is configured for Auxiliary Copy, Data Verification,
or Offline Content Indexing, then the copy data is not removed until all dependency
are fulfilled.
Use the following steps to enable Silo Space Management:
From the CommCell Browser, navigate to Policies | Storage
Policies | <Storage_Policy>.
Right-click the primary storage policy copy displayed in the right
pane and click Properties.
Click the Deduplication tab, and then click the Silo Options
tab.
In the Number of Silos to be kept in cache box, type or select
the number of dedicated data streams you want to change. The default
value is set to 1.
Select Enable Space Management check box.
Click OK.
Use the following steps to set the thresholds on the disk:
From the CommCell Browser, navigate to Policies | Storage
Resources | Library.
Right-click the disk library and then click Properties.
Click Mount Paths tab.
The silo space management follows the disk space set in the Thresholds
for Managed Disk Space.
Once enabled, Silo Storage cannot be disabled from a storage policy copy. However,
you can create a new Storage Policy without enabling silo storage and re-point the
necessary Subclients to this Storage Policy.
The Media Prediction Report can be used to identify the backup tapes that are
required for the Silo restore jobs. The following procedure provides the steps to
run a Media Prediction Report:
From the CommCell Browser, click Tools -> Reports...
From the Reports pane, navigate to Storage and click Media
Prediction.
The Silo Archive Job Summary provides job summary details of Silo archive jobs
moving backup data from disk media to Silo Storage. The following procedure provides
the steps to run a Silo Archive Job Summary report:
From the CommCell Browser, click Tools -> Reports...
From the Reports pane, click Job Summary.
From the General tab, click Administrative Jobs and then click
SILO Archiver.
The Silo Retrieve Job Summary provides job summary details of retrieve job operations
recalling data from Silo Storage. The following procedure provides the steps to
run Silo Retrieve Job Summary report:
From the CommCell Browser, click Tools -> Reports...
From the Reports pane, click Job Summary.
From the General tab, click Administrative Jobs and then click
SILO Retrieve.
Review the following consideration when using Silo Storage:
Operation
Description
Cloning Storage Policies
Storage Policies with silo-enabled copies cannot be cloned.
Look-Ahead Reader
Look-Ahead Reader operation is not applicable for Storage
Policies with Silo enabled copies.
Spool Copy
Silo-enabled Storage Policy Copies cannot be configured
as Spool Copies.
VaultTracker for Silo Storage
Data migrated to offsite storage using Silo Storage,
when required for restore operations, can be tracked and located using VaultTracker®
feature. See VaultTracker®
Feature for more information on using the feature.
Data Aging Operations
When an active Silo store has been sealed and moved to storage, all the
backup jobs that went to that store must meet the retention rules (defined
in their associated storage policy copy) for the store to become aged. Once
all of the jobs have met their retention criteria, the entire store is considered
ageable, and the Silo (tape) backup jobs are then aged. The tape designated
for the Silo storage is then refreshed and available for re-use.
Extended Retention
Extended retention rules are not supported on Storage Policy Copies
configured for Silo Storage.
If you have existing Silo enabled Storage Policy Copies with extended retention
it is recommended that you remove the extended retention settings; extended
retention on some copies would block the silo storage tapes from getting
recycled.
By
default, the Silo restore will be performed on the source MediaAgent which was used
to make the Silo backup. If necessary, you can also select a specific MediaAgent
to perform the Silo restore. This may be needed in some situations as shown in the
diagram.
