The smartctl message device is NOT READY (e.g. spun down, busy) means a SCSI readiness check did not find the device ready for the requested operation. It does not, by itself, mean the drive has failed. “Spun down” and “busy” are examples, not a diagnosis; the device’s full response and connection context are needed to determine what is happening.
What the smartctl message means
In smartctl’s SCSI reporting path, this message is emitted when a readiness check returns a generic not-ready result. smartd uses the SCSI Test Unit Ready command to check whether a device is ready for commands that depend on its media. The message alone does not say why the device returned that result. smartctl’s SCSI reporting code and smartd’s SCSI check show the separate outcomes.
The parenthetical examples should not be read as a finding that the device is spun down or busy. Nor should this message be conflated with smartmontools’ separate reports for NO MEDIUM present or device becoming ready (wait).
How to distinguish the related SCSI responses
SCSI sense information can refine the interpretation. smartmontools treats several outcomes differently, so the generic readiness message is not enough to identify a cause:
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- Not ready: A NOT READY sense response that does not match the special cases below maps to the generic not-ready result.
- No medium: A NOT READY sense key with the NO MEDIUM additional sense code is reported as a no-medium condition.
- Becoming ready: A NOT READY response with an additional sense code qualifier indicating that the device is becoming ready is treated as a wait condition.
- Unit attention: This is treated as a condition to try again.
- Medium or hardware error: These are classified separately as serious errors.
- Aborted command: This is treated as probably transport-related, rather than as the generic not-ready result.
These categories describe how smartmontools interprets responses; they do not establish what happened to a particular device. The SCSI sense classification code shows the distinctions.
What to check, in order
- Allow for startup or wake-up. If the device was just powered on or awakened, give it time to become ready, then retry once. A response explicitly indicating “becoming ready” is a distinct wait condition, not the same report as a generic not-ready result.
- Confirm that the device is present. Check whether the operating system and expected controller can see it. A readiness message alone is not evidence that replacement is necessary.
- Capture the complete command and output. Include the exact smartctl command, device model and type, host operating system, and any sense key, ASC, or ASCQ shown. Those details can separate a readiness state from no-medium, hardware, or transport-related outcomes.
- Account for the connection path. Note whether the disk is connected directly over SAS/SCSI or through a USB bridge, RAID controller, HBA, or another intermediary. If there is a bridge or controller, check whether that specific setup supports the required SCSI and SMART command pass-through. The error string alone cannot establish compatibility or identify a faulty intermediary.
- Check power-state options cautiously. smartctl documents
--nocheckmodes includingsleep,standby, andidlefor ATA/SCSI. Their behavior depends on smartmontools version and device; consult the installedsmartctlmanual before changing monitoring configuration. This is not a universal remedy for a SCSI readiness error. smartctl manual source - Investigate persistent or more serious errors. If the result continues, or the output identifies a medium or hardware error, use the complete device-specific evidence to assess the drive and connection. Those errors are separate classifications; do not infer them from the generic not-ready wording.
What information helps diagnose it
If you need help interpreting the output, provide:
- The full command and unedited smartctl output.
- The device model and the device type passed to smartctl, if any.
- The host operating system and how the device is connected: direct SCSI/SAS, USB bridge, RAID/HBA, or another route.
- Any sense key, ASC, and ASCQ values in the output.
- Whether the device was just powered up, awakened, or otherwise expected to be starting.
Without these details, it is not possible to tell whether the response reflects a temporary readiness state, absent media, a controller or transport issue, or another device-specific condition.
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Does this mean the drive is dead?
No—not from this message alone. It reports a readiness result, not a definitive failure verdict. Do not buy a replacement drive, cable, adapter, enclosure, or controller solely because this string appeared; the right next step depends on the actual sense details and the hardware path.
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