Disk Media Management

7.4 Background Media Scan (BMS)

7.4.1 Overview

This function performs a background task that verifies the entire media surface by scanning it during idle time based on the specification on Mode Page 0x1C SubPage 0x01 (Background Control mode Page). During the scan, automatic alternate processing is performed based on what is specified by the Retry Parameter. This function thus makes it possible to detect sectors early that are likely to become bad sectors and take appropriate countermeasures.

If another command is issued during the scan, that command is executed immediately to ensure that the status information during the scan, the LBA that encountered the error, and other information can be read on Log Page 0x15.

7.4.2 Background Media Scan

The Background Media Scan function can be performed in either of the following two modes:

Background Media Scan (BMS) mode

Pre-Scan mode

The subsequent sections explain both modes in detail.

7.4.2.1 Background Media Scan (BMS) mode

In this mode, the entire media surface is verified. Once one verification operation ends (either normally or midway with an error), a verification operation can be repeated after the BMS Interval Time.

When the previous verification operation ended normally, the next verification operation will begin with LBA 0.

If the previous verification operation ended with an error amid LBAs, the next verification operation will begin with the LBA that is next to the LBA that encountered the error.

7.4.2.2 Pre-Scan mode

In this mode, the entire media surface is verified immediately after power-on (Spin-Up). Once a scan ends (with normal end of entire surface verification or with an error), a scan in this mode will not begin until the following operation is performed:

1)The Mode Page EN_PS bit is cleared to '0.'

2)The Mode Page EN_PS bit is set to '1.'

3)Power on/off is performed.

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Fujitsu MBC2036RC, MBC2073RC, MBA3300RC, MBA3147RC, MBA3073RC Overview, Background Media Scan BMS mode, Pre-Scan mode