Calibration Process

Drive calibration is a one-time setup that begins as soon as you enable drive calibration. During calibration STA tests all drives in the validation pool using a Standard Verify. If you add a new drive to the media validation pool, STA automatically begins calibrating the drive. STA also automatically re-calibrates drives after a firmware update. However, STA may not be able to calibrate all drives in the pool due to a lack of calibration media or other drive factors. You should check the calibration status of the drives and address any drives that STA is unable to calibrate.

Calibration uses the following basic process for each validation drive:

1. STA performs two Standard Verify validations on the drive, each time using a different media from the calibration media logical group.
2. STA analyzes the Quality Index values for T10K drive and Read Quality (RQ) values for LTO drives. For a drive to be qualified, the following criteria must be met:
   • One media must have quality >=75. This is assigned to the drive as the primary calibration media.
   • One media must have quality >=50. This is assigned to the drive as the secondary calibration media.
3. Depending on the quality results, STA proceeds as follows:
   • If both criteria are met after two validations, the drive is calibrated. A third validation is not necessary for this drive.
   • If only one of these criteria is met after two validations, a third validation is performed using a different media from the calibration media logical group.
   • If both these criteria are not met after three validations, the drive is considered not suitable.

Calibration Results

If a drive passes calibration, STA dedicates a primary and secondary calibration media to the drive, which STA uses for all qualification on the drive.

If a drive fails calibration, STA disqualifies the drive and assigns it the Calibration State of "Not Suitable". STA will not use disqualified drives for validation as long as drive calibration remains enabled. The disqualified drives will remain in the media validation drive pool until you explicitly remove them through the library interface. If drive calibration is disabled, STA ignores the "Not Suitable" Calibration State and uses the drives for validation. This may happen if calibration was enabled on STA at one point and has since been disabled.

After STA calibrates all drives, the Media Validation Configuration screen displays, "Drive and Media Pool Setup Success--calibration has been successful." Detailed results about individual drives are displayed on the Drives – Overview screen, and you can review the results and take appropriate action.

Qualification Process and Results

Qualification is an ongoing process that runs automatically in the background whenever a media validation results in a Degraded or Failed status. During qualification, the validation drive is tested using a Standard Verify. The test are performed using the primary and secondary calibration media assigned to the drive.

Upon completion of qualification, STA makes one of the following recommendations about the quality of the drive and the media:

• The drive is disqualified.
• The data media is bad.
• The data media is bad, and the secondary calibration media is disqualified.

Qualification results are displayed on the Media Validation Overview screen in the MV Calibration and Qualification attributes. You can review the results and take appropriate action. Disqualified media are not used for drive calibration or qualification. They remain in the calibration media logical group until you explicitly remove them.

Drive Calibration and Qualification Terms

These terms are useful in understanding the concepts of drive calibration and qualification and are used throughout this section.

Validation exchange

A media and drive exchange in which the drive performs a specified validation test on the media and its data.

Failed validation

A media validation exchange that ends with a "Degraded" or "Failed" status.

False positive result

A failed validation that is the result of problems with the validation drive, not the media. STA uses drive calibration and qualification processes to reduce the possibility of false positive results and ensure that failed validations are the result of problems with the media.

Drive calibration

Optional STA media validation feature whose purpose is to ensure that validation drives are performing optimally. If drive calibration is enabled, validation drives must be calibrated before STA can use them for media validation.

Calibrated drive

Validation drive that has successfully passed the STA drive calibration process. A drive that fails calibration is considered disqualified and is not used by STA. If the STA drive calibration feature is disabled, all validation drives are considered uncalibrated, but they are used by STA.

Uncalibrated drive

A drive that has not yet been calibrated; or a validation drive in a system in which the STA calibration feature has not been enabled.

Drive qualification

Optional STA media validation feature that ensures validation drives remain calibrated and helps to ensure failed validations are the result of problems with the media, not the drive. STA automatically initiates a drive qualification process whenever there is a failed validation. Drive qualification is enabled as part of drive calibration. Drive calibration is essentially a one-time process, whereas drive qualification is ongoing.

Qualified drive

Calibrated drive that has successfully passed the STA drive qualification process.

Disqualified drive

A drive that has failed STA calibration or qualification.

Calibration media

Media that has been set aside specifically for drive calibration and qualification. You assign calibration media to a manual logical group through STA. It is highly recommended that you dedicate calibration media exclusively to drive calibration and not use them for production data. Calibration media should be of high quality.

LTO Read Quality (RQ)

Measure of the amount of error correction left on the media. This value is calculated by STA based on information provided by the drive. Read quality applies to the exchange as a whole and includes contributions from both the media and the drive involved in the exchange. This term is specific to media validation and differs from Read Margin. Read quality is reported as a percentage. A high value is desirable.

T10K Quality Index

Measure of the amount of error correction left on the media. This value is provided by the drive. During drive calibration and qualification, STA uses the quality index to determine whether the drive is qualified or disqualified. Quality is reported as a percentage. A high value is desirable.