Fujitsu MBA3300RC Init Error Recovery Methods Recommended, Command completion wait time-out

6.2 INIT Error Recovery Methods (Recommended)

(1) TASK SET FULL status

This status indicates that the HDD is currently executing processing of another command and that a new command cannot be received. The INIT that receives this status can reissue the original command.

Under a multi-initiator environment, when an INIT receives this status, the time until the HDD can receive the next command depends on the operating state with other INITs, so ordinarily, it cannot be predicted. In such a case, it is necessary for the INIT that issued the command for which this status was received to repeatedly issue the command until it is accepted.

(2) RESERVATION CONFLICT status

This status shows, under a multi-initiator environment, that the HDD is currently reserved by another INIT, and cannot be used until that reserved status is released.

The period over which the reserved status continues should be managed by the system, but normally, an INIT that receives this status reissues the original command after waiting an appropriate length of time. The wait time until a command is reissued is generally an inherent value of the system and it is necessary that consideration be given to the operating states of the other INITs in the system when deciding it.

Of the INIT which reserved the HDD falls into a state which it cannot recover from for any reason before the reserved state is released, it will be impossible for other INITs to access the HDD because that reserved state will continue. In such a case, it is necessary for the INIT to take one of the following measures to forcibly release the reserved state and recover the access right.

∙HARD RESET sequence

(3)Command completion wait time-out

This error is a state where the completed status for a command is not reported within the time expected by the INIT that issued the command.

One cause of this error occurring, besides a malfunction of the HDD, is that the command was cleared by some method which the INIT that issued the command cannot clearly detect, such as a HARD RESET sequence, or the command was cleared when an unrecoverable error was detected in arbitration processing executed by the HDD, etc. When this error occurs, then judge which recovery method to use based on the contents of the sense data (see Section 6.2.2).

Not only does command execution time differ widely depending on the type and specified contents of the command, but since it has an influence on the following factors, it is necessary to give adequate consideration to these points when setting the monitoring time value at the INIT.

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