Virtual tape media

You can use virtual tape devices to save data directly to system disk units for convenience, flexibility, and in some cases improved performance. These scenarios will give you some examples of ways that you can utilize virtual tape in your save environment.

Virtual tape is beneficial for unattended saves because it eliminates media errors that could stop an unattended save operation. If you do not allocate enough space in the virtual volumes within the image catalog to save the intended information, virtual tape will use the auto-generate feature to create additional virtual tape volumes.

Ability to duplicate to physical media

When a save is complete to a virtual tape volume, you can duplicate the data to physical media at any time and not interfere with system operations. You also have the capability to send the stream files from the virtual tape save to another system via FTP SSL. If you have multiple systems, your strategy could be to save each system to virtual tape. Then, FTP the stream files to a single system where the duplication to the physical media could take place.
Note: In a disaster recovery situation you must have physical media to perform your recovery. If you are saving to virtual tape as part of your disaster recovery strategy, you must duplicate your virtual saves to physical media.

Saving data to virtual tape media

Perform the following steps to save data to virtual tape media. The device and catalog names used here are examples. Perform steps 2 through 5 only if you have not previously created a virtual tape device, image catalog, and images to use for the save operation.

  1. Ensure that the system has enough disk space to hold all the virtual images you are going to create for your save operation.
  2. Create a virtual tape device. (You can create up to 35 virtual tape devices.)
    CRTDEVTAP  DEVD(TAPVRT01) RSRCNAME(*VRT) ONLINE(*YES)
           TEXT(text-description)
  3. Vary on the virtual tape device. 
    VRYCFG  CFGOBJ(TAPVRT01) CFGTYPE(*DEV) STATUS(*ON)
  4. Create an image catalog and virtual volumes for your save operation. 
    CRTIMGCLG  IMGCLG(MYCATALOG) DIR('/MYCATALOGDIRECTORY') CRTDIR(*YES)
           ADDVRTVOL(3) PREFIX(ABC) IMGSIZ(10000)
           TEXT(catalog-description) TYPE(*TAP)
  5. Load the image catalog. This step associates the virtual tape device to the image catalog. Only one image catalog at a time can be associated with a specific virtual tape device. 
    LODIMGCLG  IMGCLG(MYCATALOG) DEV(TAPVRT01) OPTION(*LOAD)
  6. Run a save command listing the virtual tape device in the DEV parameter. Virtual tape devices operate similar to tape media library devices so entering the volume names in the volume parameter automatically mounts the volumes.

Exclude virtual images from a full save

After you create virtual tape images, they will automatically be included when you perform a full system save using GO SAVE Option 21. The virtual tape images could significantly increase the time it takes to complete the Option 21 save operation, even if the image catalog entries do not contain data. If you want to exclude the virtual images from a full system save, use one of the following strategies:
  • Use the Change Attribute (CHGATR) command to mark the image catalog directory as non-saveable. For example: 
    CHGATR  OBJ('/Catalog-Path') ATR(*ALWSAV) VALUE(*NO)
  • Use the Load Image Catalog (LODIMGCLG) command to make the image catalog ready. Image catalogs with a ready status will be omitted from the save operation.
  • In an attended save, you can specify to omit the image catalog directories on the Save Object (SAV) command.