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CrystalDiskInfo is a free, open-source Windows utility that reads the S.M.A.R.T. data and device information reported by HDDs, SATA SSDs, NVMe SSDs, and some USB devices. It can reveal warning signs such as reallocated sectors, unreadable sectors, excessive wear, temperature events, or NVMe critical warnings. It is a monitoring and reporting tool—not a backup, repair, surface-test, speed-test, or data-recovery program—so a “Good” result is reassuring but never a guarantee.
The project’s official site currently lists version 9.9.2, released July 25, 2026; verify the latest release before downloading. Obtain it from Crystal Dew World, the official GitHub repository, or the official SourceForge files page.
What CrystalDiskInfo does
CrystalDiskInfo reads telemetry stored by a drive’s S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology) system and presents it in a graphical interface. The drive records the measurements; CrystalDiskInfo displays and interprets them. Attribute names, thresholds, and raw-value encoding vary by manufacturer, firmware, media type, and connection path.
The dashboard can show the selected physical drive’s model, firmware, serial number, drive letters, interface, transfer mode, temperature, health status, power-on time, power-cycle count, and—when the device supplies them—total host reads and writes. It can also display detailed S.M.A.R.T. attributes and export information for troubleshooting. Support is strongest for directly attached PATA and SATA drives. USB bridges, RAID controllers, virtual disks, and some NVMe paths may expose only partial data.
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CrystalDiskInfo is primarily a Windows application. It is different from CrystalDiskMark: CrystalDiskInfo monitors drive-reported health, while CrystalDiskMark measures storage performance.
Reading the main window
Select the physical drive
Use the drive selector to move between devices. Confirm the model, capacity, serial number, interface, and assigned drive letters before interpreting a warning. An external enclosure or RAID volume may hide the identity of individual member disks, so the Windows volume name alone is not always enough.
Temperature
The displayed value is normally in degrees Celsius and reflects the drive’s own sensor. Judge it against the manufacturer’s specification, drive type, ambient temperature, workload, and whether it is an idle reading or a sustained-load peak. There is no universal safe cutoff for every HDD, SATA SSD, and NVMe SSD. A repeated trend is more useful than one brief spike.
Power-on information
Power-on hours records accumulated operating time, and power-on count records starts or power cycles. They provide age and usage context, not a diagnosis. A heavily used drive can remain reliable, while a recently purchased drive can already have media or controller problems. Some older Maxtor models had a firmware counter rollover after 65,535 minutes (about 1,092 hours), a legacy limitation documented in the official FAQ.
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Where supported, Total Host Writes and Total Host Reads show data transferred by the operating system. These are not the same as internal NAND writes, which can be higher because of write amplification. A TRIM or feature indicator may also appear, depending on the device and access path.
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What Good, Caution, Bad, and Unknown mean
| Status | Meaning | What to do | What it does not prove |
|---|---|---|---|
| Good | No evaluated indicator has crossed CrystalDiskInfo’s warning criteria in the data it can read. | Continue normal use and maintain verified backups. Investigate separately if Windows reports errors, corruption, freezes, or disconnects. | It does not guarantee future reliability, complete S.M.A.R.T. visibility, sound cabling, filesystem integrity, or recoverable files. |
| Caution | At least one monitored value has reached a warning condition. | Back up important data promptly, identify the triggering row, save a report, and plan replacement when media degradation or wear is involved. | It is not a precise countdown to failure, and not every yellow warning means bad sectors. |
| Bad | A critical threshold or warning condition has been detected. | Treat the drive as unreliable. Copy the most important data or clone it while readable, avoid destructive repairs, then replace it. | It does not specify that failure will occur today; the drive may still be readable. |
| Unknown | There is not enough compatible information for a reliable assessment. | Check connections, bypass the enclosure or controller if practical, and use the manufacturer’s diagnostic tool. | It is neither a clean bill of health nor proof that the drive is failing. |
The official FAQ describes Caution and Bad as degradation warnings and recommends immediate backup: CrystalDiskInfo FAQ.
Understanding the S.M.A.R.T. table
Typical columns are Current, Worst, Threshold, and Raw Values. Current is the present normalized value; Worst is the lowest normalized value recorded; Threshold is the manufacturer-defined failure boundary when supplied. Normalized values are not universal percentages.
Raw values are manufacturer-specific counters or bit fields. A raw value of 0, 100, or any other number cannot be interpreted correctly without the exact attribute, model, firmware, and encoding. Look for whether a value is increasing, whether the normalized value crossed its threshold, and whether the computer shows read errors or disconnects. Do not compare raw numbers between unrelated drives.
Important HDD attributes
Reallocated Sector Count
The drive has removed sectors from normal use and substituted spare sectors. A nonzero or increasing count warrants a backup and investigation; it is a serious warning sign but not a failure schedule.
Current Pending Sector Count
These sectors were difficult to read and may later be remapped. Pending sectors can represent data that is currently unreadable, so prioritize copying affected files.
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Uncorrectable Sector Count
This records errors the drive could not correct during an operation. Increasing values or accompanying read errors justify replacement planning.
Spin Retry Count
Retries needed to start a mechanical spindle can indicate motor, power, or mechanical problems.
Reported Uncorrectable Errors
The drive reported errors that could not be corrected; interpretation varies by vendor, so use the model’s documentation and symptoms.
UDMA CRC Error Count
CRC errors are communication failures, often caused by a SATA cable, connector, power connection, or link-quality problem rather than damaged disk surfaces. Replace or reseat the cable and monitor whether the count continues to rise.
Important SSD and NVMe fields
Percentage Used or health percentage
This is a manufacturer-defined endurance estimate, not a literal percentage of guaranteed life remaining. Compare it with total host writes, the drive’s endurance or TBW specification, critical-warning fields, and observed errors. A 99% value does not mean a 99% guarantee; a 0% value does not prove immediate failure.
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- This USB drive provides plug and play simplicity with the included 18 inch USB 3.0 cable
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Available Spare and threshold
Available Spare is reserved flash capacity remaining for replacements; Available Spare Threshold is the vendor’s critical level. A warning means the drive’s reserve is becoming inadequate and should be treated seriously.
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NVMe critical warnings are bit fields that can indicate conditions such as spare exhaustion, reliability degradation, read-only operation, or temperature-related concerns. Consult the SSD manufacturer’s documentation for the exact bit meaning.
Media and data integrity errors
This records reported media or integrity problems. Any nonzero or increasing value should be correlated with error logs, operating-system events, and the manufacturer’s diagnostic utility.
Error Information Log Entries and Unsafe Shutdowns
Error-log entries show recorded NVMe errors. Unsafe Shutdowns count power losses or shutdowns that did not complete normally; they are useful context but do not by themselves prove NAND failure.
What to do when the status is Caution or Bad
Caution workflow
- Stop treating the drive as the only copy of important data.
- Back up irreplaceable files to a separate device or service.
- Identify the exact yellow attribute and save a CrystalDiskInfo report or screenshot.
- If pending, reallocated, or uncorrectable sectors are involved, copy critical files first and plan replacement.
- If temperature triggered the warning, improve airflow, remove dust, verify fans, and monitor the trend.
- Run the manufacturer’s diagnostic tool while the drive remains accessible.
Bad-status workflow
- Stop unnecessary normal use and do not format, initialize, or run repair operations before securing data.
- Copy the most important files first. If ordinary reads repeatedly fail, use a sector-by-sector cloning or professional recovery workflow rather than repeated file-copy attempts.
- Replace the drive after the data is safe. Do not rely on a software “bad-sector repair” to restore damaged media or worn flash cells.
Why information can be missing or misleading
USB enclosures and bridges
Many USB-to-SATA or USB-to-NVMe bridges do not pass S.M.A.R.T. commands. The enclosure, cable, power supply, or port can also cause intermittent failures. A drive may therefore show incomplete data or remain Unknown even when Windows can mount it.
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RAID and unsupported controllers
Support is conditional. The project documents partial support for selected Intel RST, Intel VROC, AMD-RAIDXpert2 (with an additional library), and some USB RAID controllers. Hardware RAID cards and other abstractions may hide member-drive telemetry. Seeing a logical volume in Windows does not guarantee direct S.M.A.R.T. access.
Unknown buffer size
The old ATA buffer-size field is obsolete or incomplete on many modern devices, so “Unknown” is normal and is not a failure indication.
Blank rotation rate
Rotation rate applies to spinning media. SSDs have no spindle, and some older drives or interfaces do not report the field. The ATA8-ACS field is not available from every device.
Disagreement with a vendor utility
Different tools may use different thresholds, firmware interpretations, and access paths. Give the manufacturer’s diagnostic utility priority for warranty or vendor-specific decisions, while retaining the CrystalDiskInfo report as additional evidence.
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- Confirm the device appears in Windows Disk Management.
- Try another USB port, cable, or powered enclosure.
- If practical, connect the drive directly through SATA or a known-compatible adapter.
- Check whether the enclosure passes S.M.A.R.T. data.
- In CrystalDiskInfo, open Function → Advanced Feature → DEBUG → USB/IEEE 1394.
- Run the drive or enclosure manufacturer’s diagnostic utility.
- If Windows cannot see the disk either, investigate power, cabling, the enclosure, or hardware rather than treating it as a display-only problem.
Download, editions, and platform limits
CrystalDiskInfo is released under the MIT License and is free for its core use. The project homepage lists Standard, Aoi, Shizuku, and Kurei Kei editions; these are presentation or packaging variants, not different levels of health accuracy. Use the official CrystalDiskInfo page, GitHub repository, or SourceForge project files, not random download portals. CrystalDiskInfo is Windows-focused; Linux users commonly use smartmontools, while macOS requires a macOS-compatible utility.
Quick Recap
Limits you should remember
- CrystalDiskInfo does not verify every file or filesystem structure.
- It does not perform a complete surface scan, benchmark, backup, clone, repair, or data recovery.
- A drive can report Good while suffering a sudden electronic failure, bad cable, controller fault, malware, filesystem corruption, or incomplete telemetry.
- A warning is a risk signal, not an exact prediction of when failure will occur.
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