| Working with Virtual Tapes | ||
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Chapter 2. Configuring a NearStore VTL Appliance | 
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| Working with Virtual Tapes | ||
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Chapter 2. Configuring a NearStore VTL Appliance |
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Like physical tapes, virtual tapes are defined by their capacity and identified by a virtual barcode called a label. To the backup application virtual tapes appear and function exactly like physical tapes, with the exception that they support a much higher transfer rate and provide greater reliability.
Because the NearStore VTL preserves the native format of the backup application when it writes data to disk, you can export virtual tapes to physical tape without the need of a conversion process. This gives you the ability to back up data to disk while still keeping the data offsite on physical tapes that are stored in the native format of the backup application.
You can also import data from any existing tape (either made by a NearStore VTL or some other application) into a NearStore VTL. When an import is successfully completed, the NearStore VTL creates a virtual tape that is the exact duplicate of the physical tape. The NearStore VTL also provides import features such as an enhanced pass-through mode and quick load.
See the section called “Importing Virtual Tapes” for more information about importing physical tapes into a NearStore VTL.
Each virtual tape has an export status. This status tells the NearStore VTL whether it needs to copy the data from the virtual tape to the corresponding physical tape during an export. If the virtual tape contains data that has not yet been copied to tape, its status is Needs export. When this virtual tape is exported, the NearStore VTL copies its data to tape.
If the data on the virtual tape is already on physical tape, the NearStore VTL simply deletes the virtual tape when it is exported. The status of this type of virtual tape is Does not need export.
Generally, a blank tape has a status of Does not need export (since it has no data to copy). Likewise, a virtual tape that has already been exported (or cloned to tape) also has an export status of Does not need export because the NearStore VTL has already copied the data to physical tape.
You can change the export status of a virtual tape from Does not need export to Needs export. This allows you to force the export of data from virtual tape to a physical tape. Changing the export status of a virtual tape is useful in the event that the corresponding physical tape has failed or is not longer available.
Virtual Tape Library Association
Although virtual tapes are associated with a specific virtual library, they are not strictly tied to that library. You can move virtual tapes between compatible virtual libraries. In order for virtual libraries to be considered compatible, they must use the same virtual tape drive type.
See Creating/Editing Virtual Tape Drive Types for more information.
This subsection provides the following tasks:
The NearStore VTL provides a comprehensive list of virtual tapes on the Virtual Tape List screen. This list includes the label, virtual library association, number of tape files, export status, and size of each virtual tape.
From the Configuration Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
The Virtual Tape List screen appears. At the top of the screen the drop-down menu Library controls whether the virtual tapes for all libraries, or just a selected one, are listed. The screen displays the following information:
Label—displays the label (virtual barcode) of the virtual tape. If you click the label of a specific virtual tape, the NearStore VTL displays the Update Virtual Tape screen for the specified virtual tape.
Customer—(displayed if the advanced option Use Customer is selected) provides the name of the customer to whom the virtual tape belongs. This field is displayed only if the customer option is enabled under Configuration Options > Advanced.
Library—(displayed if ALL is selected in the Library drop-down menu) provides the name of the virtual library in which the virtual tape resides.
Files—specifies the number of tape files that are contained in the virtual tape. Tape files are not the individual files that are backed up by the backup application. Rather, they are data separated by file marks.
Write Protected—displays the write-protected status of the virtual tape. If the status is Read Only, the virtual tape cannot be written to. If the status of the virtual tape is Writable, the virtual can be written to. You can change the write-protected status of a virtual tape from Configuration Tasks >Virtual Tapes >Change Write Protected Status.
Need to export—specifies whether the virtual tape needs to be copied to a physical tape when it is exported. If the virtual tape needs to be copied, the value Needs Export is displayed. If the virtual tape does not need to be copied, the value Does not need export is displayed. A volume does not need to be exported if no changes have been made to it since it was created, imported, or cloned.
Raw Capacity—gives the specified capacity of the drive.
Data Written—specifies the amount of uncompressed data that the NearStore VTL has written to the virtual tape.
Space Remaining—provides the amount of disk capacity that is remaining.
Disk Used—provides the amount of disk being used by the virtual tape.
Tape Smart Sizing—lists whether the virtual tape uses tape smart sizing. If the virtual tape does, the field displays the tape optimization algorithm used. If it does not, the field displays DISABLED.
The NearStore VTL has a user-configurable option that you can use to set the write-protected status of virtual tapes. Virtual tapes that are in a protected state cannot be written to but data can be read from them.
Virtual tapes that are in a nonprotected state can have data written to and read from them.
Complete this task to change the write-protected status of a virtual tape:
From the Configuration Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
Click the Change Write Protected Status tab, located in the upper portion of the screen.
The Change Write Protected Status screen appears. At the top of the screen the drop-down menu Library controls whether the virtual tapes for all libraries, or just a selected one, are listed. The screen displays the following information:
Label—gives the label of the virtual tape. This label is used in the same way as the barcode of a physical tape.
Customer—specifies the name of the customer with which the virtual tape is associated. This field is present only if the Use Customer option has been enabled from Configuration Tasks >Advanced.
Library Name—provides the name of the virtual library in which the virtual tape resides.
Write Protected—displays the current status of the virtual tape. Valid states are Writable and Read Only. When a virtual tape is set to a protected state (Read Only), it can still be exported to physical tape.
Select one or more tapes by selecting the check box in front of the tape labels. To select all tapes, select the check box in the column heading
Click the Set Read-only button to set the protected status to read-only, or click the Set Writable button to set the protected status to writable.
Each virtual tape has an export status that tells the NearStore VTL whether to copy its data to physical tape during an export. If the export status is Needs export, the NearStore VTL copies the data from the virtual tape to physical tape. If the export status is Does not need export, the NearStore VTL deletes the virtual tape without copying the data.
The export status of a virtual tape depends on whether its data also exists on a corresponding physical tape. For example, if a virtual tape is the result of a tape import (and the backup application has not written data to the virtual tape), the virtual tape and the tape have the same data. In this case, the export status of the virtual tape is Does not need export. This is also true if the NearStore VTL cloned the virtual tape or if the virtual tape is new.
If, on the other hand, the backup application writes data to this virtual tape, The NearStore VTL changes its export status from Does not need export to Needs export. This is because the virtual tape now contains data that is not currently on the physical tape.
When you export a virtual tape, it is important that the corresponding physical tape contains the most up-to-date information. This helps to ensure that no data is lost when you export the virtual tape.
As mentioned previously, if the Export status of the virtual tape is Does not need export, the NearStore VTL does not copy the data from the virtual tape to the corresponding tape when it exports the virtual tape. This can be a problem if corresponding physical tape is either lost or damaged.
For this reason, you can force the export of data from a virtual tape to physical tape. When you change the export status of a virtual tape from Does not need export to Needs export, the NearStore VTL copies the data from the virtual tape to physical tape during an export.
Complete this task to change the export status of a virtual tape:
From the Configuration Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
Click the Change Export Status tab, located in the upper portion of the screen.
The Change Export Status screen appears. At the top of the screen the drop-down menu Library controls whether the virtual tapes for all libraries, or just a selected one, are listed. The screen provides a list of virtual tapes that do not have to be copied to physical tape when they are exported.
Label—gives the label/virtual barcode of the virtual tape. The label of a virtual tape can be thought of in the same way as the barcode label on a physical tape. If the virtual tape was imported from a physical tape, the label of the virtual tape is the same as the barcode of the physical tape.
Library Name—provides the name of the virtual library in which the virtual tape resides.
Customer—specifies the customer to which the virtual tape belongs. This field is displayed only when the Customer option is enabled from Configuration Tasks > Advanced > Options.
Select one or more tapes by selecting the check box in front of the tape labels. To select all tapes, select the check box in the column heading
Click the Force Export button to force the export of the selected tapes.
The selected virtual tape no longer appears on the Change Export Status screen. The status of the virtual tape, as listed in the Need to Export field of the Virtual Tape List screen, changes from Does not need export to Needs export.
At some point, you might want to move virtual tapes between virtual libraries. This is possible as long as both virtual libraries use the same virtual tape drive types, and storage pool. Moving virtual tapes is useful in the event that you want to consolidate virtual libraries or move virtual tapes into a virtual library of a different size.
If you have enabled the Customer option, you must ensure that both the source and destination virtual libraries are owned by the same customer account. This is a safeguard that prevents sensitive information from being accidentally moved between customer accounts. See the section called “Working with Customer Accounts” for more information.
Complete this task to move a virtual tape between compatible virtual libraries:
From the Configuration Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
Click the Move Virtual Tape tab, located in the upper portion of the screen.
Set the Source Library to the library containing the virtual tape you want to move.
Set the Destination Library to the destination library.
Select individual tapes to move by clicking the box next to the tape name, or select all tapes by clicking the box next to the column heading Tape Label.
When you no longer need a virtual tape, you can delete it from the system. Deleting a virtual tape removes it from the system and frees up the associated disk space and memory.
You cannot delete a virtual tape if the tape is “in use.” A virtual tape is in use if it is loaded into a drive or referred to in an import or export request.
One consideration when deleting a virtual tape is whether you might need the data in the future. If there is any chance that you will need the data, export the virtual tape to physical tape rather than delete it.
After the physical tape is successfully written, the exported virtual tape is deleted.
See the section called “Changing the Export Status of a Virtual Tape” for more information.
Complete this task to delete a virtual tape:
From the Configuration Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
Click the Delete Virtual Tape tab, located in the upper portion of the screen.
The Delete Virtual Tape screen appears. At the top of the screen the drop-down menu Library controls whether the virtual tapes for all libraries, or just a selected one, are listed. The screen displays the following:
Tape Label—uniquely identifies each virtual tape. This corresponds to the barcode label on a physical tape.
Customer—provides the name of the customer with which the virtual tape is associated. This field is displayed only when the Use Customer option is enabled from Configuration Tasks > Advanced.
Data Written—displays the size of the virtual tape.
Disk Used—displays the amount of disk space in use by the tape.
Need to Export—displays either Needs export or Does not need export, depending on whether the physical tape and virtual tape contain the same data.
Select one or more tapes by selecting the check box in front of the tape labels. To select all tapes, select the check box in the column heading.
Click the Delete button.
When prompted, click Apply to delete the selected virtual tapes.
When you click Apply, the NearStore VTL permanently deletes the data on the virtual tape.
The NearStore VTL deletes the virtual tape, and the associated disk space is made available.
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| Managing Virtual Device Access |  |
Working with RAID Groups |
Copyright © 1994-2006, Network Appliance, Inc. All rights reserved.
Part number 210–01204_A0
Preliminary edition
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