Qualifying tape drives dynamically

What a qualified tape drive is

A qualified tape drive is a tape drive that has been tested and found to work properly on Network Appliance filers. A qualified tape drive is in the Data ONTAP kernel's internal tape qualification list.

How to qualify a tape drive dynamically

You can qualify a nonqualified tape drive by entering a valid tape qualification file in the filer's /etc/tape_config directory. You get the information you need for this file from the tape vendor's drive documentation. You can use a text editor to create the tape qualification file. There can be multiple files in the directory, one for each model being qualified.

How to format the tape qualification file

The /etc/tape_config directory contains a sample tape qualification file, which includes an explanation of the requirements for a tape qualification file, a list of the default SCSI command timeout values used by the tape drive, and an example of a tape qualification file.

When you create a new tape qualification file, you can use any valid file name, except a file name that begins with a period (.).

The format of the tape qualification file is as follows:

vendor_id (string, limit of 8 bytes)--The vendor ID as reported by the SCSI Inquiry command.

product_id (string, limit of 16 bytes)--The product ID as reported by the SCSI Inquiry command.

id_match_size (number)--The number of bytes of the product ID to be used for matching to detect the tape drive to be identified, beginning with the first character of the product ID in the Inquiry data.

vendor_pretty (string, limit 16 bytes)--If this parameter is present, it is specified by the string displayed by sysconfig -v or sysconfig -t; otherwise, the INQ_VENDOR_ID is displayed.

product_pretty (string, limit 16 bytes)--If this parameter is present, it is specified by the string displayed by sysconfig -v or sysconfig -t; otherwise, the INQ_VENDOR_ID is displayed.

Note
The vendor_pretty and product_pretty fields are optional, but if you specify a value for one of these fields, you must also specify a value for the other.

You must specify a description, density code, and compression algorithm for l, m, h, and a, as follows:

{l | m | h | a}_description= (string, limit 16 bytes)--The string to print for sysconfig -t that describes characteristics of the particular density setting
{l | m | h | a}_density= (hex codes)--The density code to be set in the SCSI mode page block descriptor corresponding to the desired density code for l, m, h, or a
{l | m | h | a}_algorithm= (hex codes)--The compression algorithm to be set in the SCSI Compression Mode Page corresponding to the density code and the desired density characteristic

The following fields are optional:

autoload= (Boolean yes/no)--Set this field to yes if the tape drive has an automatic loading feature; that is, after you insert a tape cartridge, the tape drive becomes ready without the need to execute a SCSI load (start/stop unit) command. The default for this field is no.
cmd_timeout_0x*--Individual timeout value. Use this field only if you want to specify a different timeout value from the one being used as a default by the tape driver. The sample file lists the default SCSI command timeout values used by the tape driver. The timeout value can be expressed in minutes (m), seconds (s), or milliseconds (ms).

Example of a tape configuration file

The following example shows a tape configuration file for the tape drive Tape Drive 2001.

  vendor_id="TAPECO"

  product_id="TAPEDRIVE2001"

  id_match_size=11

  vendor_pretty="Tape Company"

  product_pretty="Tape Drive 2001"

    l_description="2 GB"

    l_density=0x01

    l_algorithm=0x81

    m_description="4 GB (compression)"

    m_density=0x01

    m_algorithm=0x82

    h_description="6 GB"

    h_density=0x10

    h_algorithm=0x88

    a_description="12 GB (compression)"

    a_density=0x10

    a_algorithm=0x89

  autoload="yes"

  # no entry for autoload is the same as autoload="no"

  cmd_timeout_0x01=5m

  cmd_timeout_0x12=700ms

  cmd_timeout_0x1b=60s

How the filer qualifies a new tape drive dynamically

The filer's /etc/tape_config directory is created automatically when the filer boots. When you add a tape qualification file to this directory, the filer checks the file's format at the next boot time or the next time any tape is accessed. If the format is valid, the information is entered into the internal tape qualification table and a success message similar to the following is printed to the console and system log. Information about the tape persists as long as the file is in the directory or until the file is altered.

Dynamic Tape Qualification file:/etc/tape_config/filename format 
check was successful. Internal tape qualification table was updated 
with Tape Drive product information.

If the format is incorrect, an error message similar to one of the following is printed to the console and system log.

Dynamic Tape Qualification file: /etc/tape_config/filename has 
missing or badly formatted required key(s).

Dynamic Tape Qualification file: /etc/tape_config/filename has a 
format error in the information appended to the required key.

When you connect a tape drive to the filer, the filer looks for a product_id match between information obtained during the tape discovery process and information contained in the internal tape qualification table. If a match is discovered, the drive is marked as qualified and the filer can access the tape drive. If a match is not found, the tape drive remains in the unqualified state and is not accessed.

Qualified SCSI drives must be attached to the filer before reboot to be recognized; qualified Fibre Channel drives are recognized whenever they are attached.