If an HP system stops at boot with SMART hard disk error 301, the drive's own self-monitoring has reported a statistic past a threshold the system firmware treats as a warning. The message names the drive that raised the warning — it does not say which attribute caused it, or how severe it is.
What the 301 warning does and does not tell you
Firmware warnings of this kind are threshold-based. A drive with a handful of reallocated sectors and a drive with widespread unreadable sectors can raise the same message. To tell those apart you have to read the underlying values.
The attributes that actually matter
Three attributes indicate genuine media defects. The Drive Health Check reports each as a raw value:
- Reallocated sector count — sectors the drive has already retired and replaced from its spare pool.
- Current pending sector count — sectors the drive could not read reliably and has not yet remapped.
- Uncorrectable sector count — sectors that failed even with error correction applied.
It also reports power-on hours, power cycle count, temperature and, for SSDs, a remaining-health figure — useful context when deciding whether a warning reflects wear or a defect.
How to read the values without installing anything
- Boot the ITAD Tools iPXE toolkit on the affected machine.
- Select Drive Health Check from the menu.
- Let it read SMART data — the check is read-only and changes nothing.
- Compare the three sector attributes against your own grading policy.
Because it boots over the network or from USB, it works on machines whose installed OS no longer starts — common on hardware that has already been pulled for disposition.
Run the free bootable Drive Health Check
The ITAD Tools iPXE toolkit reads SMART data read-only, with no installed operating system and nothing to install on the machine.
Frequently asked questions
What does SMART hard disk error 301 mean?
It means the drive's built-in self-monitoring reported a value past a threshold the system firmware treats as a warning. It identifies which drive raised the warning, not which attribute caused it.
Is error 301 always a failing drive?
No. The warning is threshold-based. Reading the underlying attribute values tells you whether the drive has real defects or crossed a conservative threshold.
Can I clear or reset SMART error 301?
The warning reflects stored drive statistics, which are not resettable. The Drive Health Check is read-only and does not clear, reset, or remap anything.
Which SMART values should I check after error 301?
Reallocated sector count, current pending sector count, and uncorrectable sector count are the ones that indicate real media defects.
How do I read SMART values without installing anything?
Boot the free ITAD Tools iPXE toolkit and choose Drive Health Check. It reads SMART data read-only, with no installed OS.