Data Compression Characteristics mode page fields:
DCE | Data Compression Enable. This bit controls whether the drive uses compression when | |
| writing. The value has no meaning when reading, that is, if the tape contains | |
| compressed data, decompression will occur regardless of the setting of this bit. | |
| The bit is analogous to the Select Data Compression Algorithm field on the Device | |
| Configuration mode page (see page 81). | |
| 0 | Compression is disabled |
| 1 | Compression is enabled |
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DCC | Data Compression Capable | |
| Read only. It will have the value of 1, indicating that compression is supported. | |
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DDE | Data Decompression Enable | |
| Read only. It will have the value of 1, indicating that compression is enabled. | |
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RED | Report Exception on Decompression | |
| Read only. It will have the value 0, meaning that the drive returns CHECK CONDITION | |
| status when it encounters data that cannot be decompressed. This applies when data | |
| has been compressed with an unknown or unsupported compression algorithm. | |
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Compression | This indicates which compression algorithm will be used to process data from the host | |
Algorithm | when the DCE bit is set to one. If the host selects an algorithm which the drive does not | |
| support, CHECK CONDITION is returned, with a sense key of ILLEGAL REQUEST. Only | |
| the default algorithm (ID 1) is supported. | |
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Decompression | This will also always be 1, indicating that the default decompression algorithm should | |
Algorithm | be used. | |
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80 Commands