SMART Errors and Data Recovery
What Your Drive Is Telling You Before It Fails
SMART (Self-Monitoring, Analysis, and Reporting Technology) is a monitoring system built into every hard drive and SSD. When it flags errors, your drive is reporting real physical damage. This guide explains which attributes matter, what the numbers mean, and when to stop using the drive and call a professional.
What Is SMART and Why Does It Matter?
Every modern hard drive and SSD tracks its own health through SMART. The drive firmware monitors dozens of internal metrics: sector errors, read retries, temperature, spin-up time, and more. When these values cross manufacturer-set thresholds, the drive reports a warning or failure status.
SMART does not catch every failure. Sudden mechanical events like a dropped drive or power surge can kill a drive with a clean SMART report. But when SMART does flag something, it is almost always real. The drive is not guessing. It is reporting measured physical degradation.
Tools like CrystalDiskInfo (Windows), smartmontools (Linux/Mac), and manufacturer utilities can read SMART data. The raw numbers matter more than the "health" percentages these tools display, because each tool interprets thresholds differently.
Critical SMART Attributes (Hard Drives)
These five attributes are the strongest predictors of hard drive failure. Backblaze analyzed tens of thousands of drives and found that 76.7% of drive failures showed non-zero values in SMART 5, 187, 188, 197, or 198 before failure.
SMART 5 (0x05)
Reallocated Sector Count
Count of sectors that have been remapped due to read/write errors. The drive has found bad sectors and moved data to spare areas.
Any non-zero value indicates the drive is using spare capacity to work around bad sectors. Values over 100 are a strong warning sign. Back up immediately and plan for replacement. Values under 10 may be acceptable short-term but warrant monitoring.
SMART 197 (0xC5)
Current Pending Sector Count
Count of sectors waiting to be remapped. These sectors had read errors and are marked as 'unstable.' If a subsequent write to the sector succeeds, the drive clears the pending flag and keeps the sector in service without reallocating it. If the sector also fails on write, the drive reallocates it to a spare area.
This is the strongest single predictor of imminent drive failure. Any non-zero value means the drive is currently struggling to read data. Values over 100 indicate critical failure is likely within days or weeks. Stop using the drive and seek professional recovery immediately.
SMART 198 (0xC6)
Offline Uncorrectable Sector Count
Count of uncorrectable errors found during offline scans. Similar to SMART 197, but detected during background self-tests rather than normal operations.
High values indicate sectors that couldn't be recovered even during dedicated scans. Combined with SMART 197, this gives a complete picture of unrecoverable sectors. Non-zero values warrant immediate backup.
SMART 187 (0xBB)
Reported Uncorrectable Errors
Count of errors that couldn't be corrected using hardware ECC (Error Correcting Code). These are read errors that persisted despite multiple retries.
Each increment means the drive failed to read data even with error correction. This directly indicates data loss has occurred. Any non-zero value is serious.
SMART 188 (0xBC)
Command Timeout
Count of operations that didn't complete within the expected time. Can indicate various issues from minor firmware problems to severe mechanical failures.
Command timeouts can have many causes. A few isolated timeouts may be benign (power fluctuation, cable issue). Consistently increasing values suggest mechanical issues where the drive is struggling to position heads or spin platters.
SMART 9 (0x09)
Power-On Hours
Total hours the drive has been powered on. Not a failure predictor itself, but useful context for other attributes.
Drives with 30,000-50,000+ hours are in their later life. This doesn't predict failure directly, but does indicate the drive has been working for 3-5+ years continuously. Combined with other SMART warnings, high hours suggests replacement should be planned.
SMART 194 (0xC2)
Temperature
Current drive temperature in Celsius. Sustained high temperatures accelerate mechanical wear.
Keep drives under 45°C for optimal life. Brief spikes to 50°C during heavy use are acceptable. Sustained temperatures over 50°C significantly reduce lifespan. Drives running over 60°C are at high risk of thermal damage.
SSD-Specific SMART Attributes
SSDs share some SMART attributes with hard drives (like Reallocated Sector Count) but also have unique attributes related to flash wear and controller health. Unlike HDDs, SSD SMART attribute IDs are not fully standardized across manufacturers.
Attribute ID varies by manufacturer
Available Reserved Space
Percentage of spare blocks remaining. SSDs set aside reserve blocks to replace cells that wear out. When this drops below the manufacturer threshold, the drive has used most of its spare capacity. The attribute ID for this metric is not standardized: Intel/Solidigm reports it as 232 (0xE8), Samsung uses 180 (0xB4), and other vendors assign their own IDs.
A value below 10% means the SSD is running low on spare blocks. Below 3% is critical. The drive may start reporting write errors or go read-only to protect remaining data. Check your manufacturer's SMART documentation for the correct attribute ID, then plan replacement if this value is declining.
SMART 177 (0xB1) on Samsung; varies by vendor
Wear Leveling Count
Tracks the number of program/erase cycles across flash cells. Every SSD flash cell has a limited number of writes before it wears out. Consumer TLC NAND is typically rated for 1,000-3,000 cycles.
This value increases over the life of the drive. When it approaches the manufacturer's rated endurance, the SSD is nearing end of life. Some controllers report this as a countdown (100 to 0) while others report raw cycle counts. Check your SSD manufacturer's documentation for interpretation.
SMART 241 (0xF1)
Total LBAs Written
Cumulative count of logical blocks written to the drive over its lifetime. Combined with the drive's TBW (Total Bytes Written) rating, this tells you how much of the SSD's write endurance has been consumed.
Compare this value against your SSD's rated TBW endurance from the datasheet. If your actual writes exceed 70-80% of the rated TBW, plan for replacement. The drive will not fail immediately at 100% but the risk of cell-level errors increases.
SSD firmware failures are different from wear-out. Many SSD failures are not predicted by SMART at all. Controller lockups, firmware bugs (like the SATAFIRM S11 issue), and sudden power loss corruption can kill an SSD with perfect SMART values. See our SSD data recovery page for more on these failure modes.
Hard Drive Data Recovery Standards & Verification
Our Austin lab operates on a transparency-first model. We use industry-standard recovery tools, including PC-3000 and DeepSpar, combined with strict environmental controls to make sure your hard drive is handled safely and properly. This approach allows us to serve clients nationwide with consistent technical standards.
Open-drive work is performed in a laminar-flow bench filtered to 0.02 µm, verified using TSI P-Trak instrumentation.
Transparent History
Serving clients nationwide via mail-in service since 2008.
Media Coverage
Our repair work has been covered by The Wall Street Journal and Business Insider, with CBC News reporting on our pricing transparency. Louis Rossmann has testified in Right to Repair hearings in multiple states and founded the Repair Preservation Group.
Aligned Incentives
Our "No Data, No Charge" policy means we assume the risk of the recovery attempt, not the client.
Technical Oversight
Louis Rossmann
Louis Rossmann's well trained staff review our lab protocols to ensure technical accuracy and honest service. Since 2008, his focus has been on clear technical communication and accurate diagnostics rather than sales-driven explanations.
We believe in proving standards rather than just stating them. We use TSI P-Trak instrumentation to verify that clean-air benchmarks are met before any drive is opened.
See our clean bench validation data and particle test videoWhy Recovery Software Makes SMART Failures Worse
When SMART reports reallocated or pending sectors, the drive is physically struggling to read certain areas of its platters. Recovery software like Recuva, Disk Drill, or R-Studio attempts to scan the entire drive surface, including the damaged areas.
Every read attempt on a degrading drive puts mechanical stress on the heads. The heads must repeatedly seek to the damaged sectors, retry reads, and reposition. This accelerates wear on heads that may already be weak. A drive that was recoverable through professional imaging can become unrecoverable after hours of aggressive software scanning.
Professional recovery tools like the PC-3000 handle this differently. They image the drive by skipping bad areas first, capturing good data quickly, then carefully working through damaged regions with controlled retry counts and head parking between passes. This approach recovers more data while putting less stress on the drive.
What Happens When You Ignore SMART Warnings
- 1.Sectors continue to degrade. Repeated retries on damaged sectors stress read/write heads that may already be degraded. Weakened heads can eventually crash into the platter surface, creating new damage in unrelated areas of the disk.
- 2.Heads weaken from overwork. The heads are spending more time over damaged areas, accumulating wear that shortens their remaining life.
- 3.The drive stops responding entirely. What started as slow reads and SMART warnings becomes a clicking drive or a drive that is no longer detected.
- 4.Recovery becomes more expensive. A drive that needed imaging ($300-$800) now needs a head swap ($1,200-$1,500) because continued use destroyed the heads.
When to Act: SMART Error Decision Framework
Use this framework to decide what to do based on your drive's SMART data. The categories are based on Backblaze failure correlation data.
Monitor
- All critical attributes (05, C5, C6, BB, BC) at zero
- Temperature under 45°C sustained
- Power-On Hours under 30,000
Action: Maintain regular backups. Recheck SMART every 3-6 months. No immediate concern.
Back Up Now
- Reallocated sectors (05) between 1-100
- Pending sectors (C5) between 1-10
- Uncorrectable errors (BB) non-zero
- Temperature sustained over 50°C
Action: Back up all data immediately. Clone the drive with ddrescue if possible. Plan replacement within weeks. Do not run recovery software.
Stop Using the Drive
- Pending sectors (C5) over 100
- Reallocated sectors (05) over 100 and climbing
- SMART status reports "BAD" or "FAILED"
- Drive is showing corruption, slow reads, or freezing
Action: Power down the drive. Do not attempt DIY recovery. Contact a professional data recovery lab for imaging.
SMART Error Recovery Pricing
Cost depends on how far the drive has degraded. Drives caught early with minor SMART warnings are typically the least expensive to recover.
Bad Sector Imaging
Drive still reads but has SMART warnings. Professional imaging to bypass bad sectors.
$300-$800
Head Degradation
SMART warnings progressed to clicking or intermittent detection. Head swap required.
$1,200-$1,500
Complete Failure
Drive no longer spins or is not detected. May need head swap, motor work, or firmware repair.
$1,200-$2,000
No Data, No Charge: If we cannot recover your data, you pay nothing (optional return shipping only). Free evaluation with no obligation. See our full pricing page for details.
Frequently Asked Questions
What does 'SMART status BAD' mean?▾
Your drive's self-monitoring system has detected one or more attributes that exceed manufacturer-set failure thresholds. This is different from a warning. A BAD status means the drive's own firmware considers failure imminent or already occurring. Back up immediately and do not run recovery software on the drive.
Can a drive fail with all SMART values at zero?▾
Yes. SMART monitors gradual degradation, not sudden failures. A power surge, dropped drive, or sudden head crash can destroy a drive with perfect SMART history. SMART catches roughly 36-64% of failures depending on the study. It is useful when it flags something, but a clean report is not a guarantee of health.
Which SMART attribute is the strongest failure predictor?▾
SMART 197 (Current Pending Sector Count). According to Backblaze data, drives with more than 100 pending sectors fail at 391 times the rate of drives with zero. This is because pending sectors mean the drive is actively struggling to read data right now, not just reporting historical damage.
Do SSDs use the same SMART attributes as hard drives?▾
No. SSDs share some standard attributes like Reallocated Sector Count (ID 05) but also report SSD-specific attributes that hard drives do not have. These include reserved block counts, wear leveling data, and total bytes written. The attribute IDs for these metrics are not standardized across SSD vendors. For example, reserved space reporting uses different attribute IDs on Intel/Solidigm, Samsung, and Micron drives. Always check your SSD manufacturer's documentation for correct interpretation.
Should I run chkdsk or fsck if SMART shows errors?▾
No. If SMART is reporting bad or reallocated sectors, running filesystem repair tools forces the drive to attempt reads across its entire surface. This puts maximum stress on a drive that is already failing. Each failed read attempt can cause the heads to degrade further or additional sectors to go bad. Clone the drive first with a tool like ddrescue, then run filesystem repair on the clone.
My SMART data shows high Power-On Hours but nothing else is flagged. Is my drive failing?▾
Not necessarily. Power-On Hours (SMART 09) alone does not predict failure. A drive with 40,000 hours and clean sector counts is in better shape than a drive with 5,000 hours and rising reallocated sectors. High hours do indicate that mechanical parts have wear, so it is reasonable to plan a replacement and keep backups current, but there is no hard cutoff where hours alone mean failure.
How much does data recovery cost when SMART shows errors?▾
It depends on the underlying damage. If the drive still reads but has growing bad sectors, recovery through professional imaging typically costs $300-$800. If the drive has progressed to clicking, not spinning, or not being detected, the mechanical failure behind the SMART warnings may require a head swap or other clean bench work at $1,200-$2,000. We provide a firm quote after free evaluation.
Can I reset or clear SMART data to fix the errors?▾
Some vendor tools allow resetting SMART counters, but this changes the report without fixing the drive. The bad sectors, weak heads, or worn flash cells are still there. Resetting SMART data is something used-drive sellers do to hide problems. If you are seeing SMART errors on your own drive, the data reflects real physical damage that will continue to worsen.
SMART Errors? Get a Free Diagnosis.
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