Using Virtual Tapes

Using Virtual Tapes
	Chapter 3. Using a NearStore VTL Appliance

A virtual tape is the logical equivalent of a physical tape. Virtual volumes are used in virtual libraries in much the same way that physical tapes are used in physical tape libraries.

When the NearStore VTL writes data to virtual tapes (disk), it preserves the native format of the backup application. Even the tape marks and record size changes are preserved. This means that the NearStore VTL can copy data to and from physical tape without the need of a conversion process. In fact, virtual tapes have a one—to—one correlation with physical tapes.

For example, the NearStore VTL takes the data that the backup application sends during a backup and stores it on a virtual tape that has the same capacity and barcode as its corresponding physical tape. Having a physical tape that corresponds to each of the virtual tapes is important if you plan to back up the virtual tapes to physical tape for offsite storage.

You can create virtual tapes when you create a virtual library, or you can create them later. This section describes the way in which you can create virtual tapes manually.

This section provides the following tasks:

Creating Virtual Tapes Manually
Importing Virtual Tapes

Creating Virtual Tapes Manually

Virtual volumes can be created when a virtual library is created, when a physical tape is imported into the NearStore VTL, or by manual operation.

The capacity of the new virtual tapes matches the capacity of the virtual tape drives in the virtual library for which the virtual tapes were created.

Even if all the slots in a virtual library are full, additional virtual tapes can still be created for that virtual library. In this case, the virtual tapes appear in the virtual tape cart on the left side of the virtual library.

When you have disabled the option that moves virtual tapes from the entry port to a slot, the NearStore VTL keeps newly-created virtual tapes in the cart until the mail slot is available.

Note

Backup applications cannot see virtual tapes that are situated in the virtual tape cart.

Complete this task to create virtual tapes:

From the Daily Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.

The Create Virtual Tape screen appears.
Complete the following information:

Library—provides a drop-down menu from which a virtual library can be selected.

Starting Tape Label—provides an alphanumeric name for the first virtual tape in the sequence. It is important that the labels of the virtual tapes be chosen carefully. The preferred method is to label the virtual tapes with the barcodes of the physical tapes to which you will export them.

Note

If you have enabled the option to constrain volume labels, you have to ensure that your starting label falls within the label parameters that you have set up. See Creating Virtual Libraries for more information.

No. of Tapes—specifies the number of volumes to be created. The labels of each additional volume are automatically incremented based on the starting volume label. For example, if the starting volume label is abc123, additional volumes will be labeled abc124, abc125, abc126, and so on.

If there are no numbers in the starting volume label, the last letter of the label is incremented for each additional volume. For example, if the starting volume label is tapeA, additional volumes will be labeled tapeB, tapeC, tapeD, and so on.

(Optional) you can click Reset, to clear any configuration parameters prior to clicking Apply.
Click Apply.

The virtual tapes are added to the specified virtual library. If the option to move the new virtual tapes from the entry port to an available slot is enabled, each new virtual tape is moved to an available slot.

See Working with Virtual Libraries for detailed information about the option to move new virtual tapes to an available slot.

If the virtual tapes need to be manually loaded into the virtual library, the Virtual Library Management screen appears.

Importing Virtual Tapes

When you need to read, append, or overwrite data that is on a physical tape, you must first import that tape into the NearStore VTL appliance.

Depending on the needs, you can choose to import either all or just the first megabyte of data from the physical tape. Importing all of the data from the tape is useful if you are going to do multiple restores or append the tape. When you are going to overwrite an existing physical tape, you must import at least the first megabyte of data into the NearStore VTL. This enables the backup application to verify that it is the correct volume.

If the physical tape requested by the backup application is currently in a physical tape library that is connected to the NearStore VTL appliance, NearStore VTL uses the robotic arm of the physical tape library to move the physical tape into an available physical tape drive. If the physical tape is not in the physical tape library (or if the drive is a stand-alone device), the administrator is asked to load the physical tape into an available physical tape drive.

Once the physical tape is loaded, the NearStore VTL creates a virtual tape that has the same barcode as the physical tape. If you have enabled the option to automatically move volumes from the import/export port to an available slot, the virtual tape is moved directly into an available slot. If you have not enabled this option, the virtual tape remains in the import/export slot. As soon as the virtual tape is created it becomes both visible and available to the backup application.

While you are in the process of importing data from a physical tape, you can restore specific data, including data that has not yet been imported. This is made possible by putting the NearStore VTL into pass-though mode. Pass-through mode is initiated when you use the backup application to access data that is in the process of being imported.

If the requested data has already been copied to the virtual tape, the backup application can access it while the NearStore VTL continues to import data. If the requested data has not been copied to the virtual tape, the NearStore VTL pauses the import, locates the requested data, and copies it to the virtual tape. The backup application can then get the data from the virtual tape.

Once you have accessed the required data, you can either export the tape or have the NearStore VTL continue to import it.

The following must be taken into account when importing physical tapes:

Available Disk Space—there must be enough available physical disk space for the data that is being imported.

Complete this task to import physical tapes to virtual tapes:

From the Daily Tasks menu, located on the left side of the screen, click the Virtual Tapes task category.
Click the Import Virtual Tape tab, located in the upper portion of the screen.

The Import Virtual Tape Screen appears.
Complete the following information:

Library—provide the name of the virtual library into which the physical tape is to be imported.

Special Instructions—specify which special instructions are included with the import.

Valid special instructions are:
- None—the entire tape is imported. This method is useful when additional data is going to be append to an old tape or if the tape is required for multiple restores.
- Read-only—the physical tape is imported as read only.
- Quick-load—the beginning of a physical tape is imported. This method is useful when an old tape is required for overwriting. This option might not be compatible with all backup software.
- Action—check this box to indicate that you want to import the physical tape. You can select either one or multiple tapes for import.
- Volume Label—give the name (barcode) of the physical tape to be imported. The physical tape must already exist. It is important that the name of the virtual tape (specified in the Volume field) matches the barcode, including the case, of the physical tape that is being imported into the virtual library.
- Changer—provide a link to the Changer Inventory screen for the specified physical tape library. You can use this screen to rescan the physical tape library and update the list of virtual tapes.
(Optional) you can click Reset to clear all configuration parameters prior to clicking Apply.
Click Apply.

Once an import request has been applied, a volume mount request will be created. If the Use Tape Pick List option has been enabled from Configuration Tasks > Advanced > Options, a pick list action will also be created.


Using Virtual Libraries		Using Physical Tapes (Loading Physical Tape Drives)