If you\u2019ve noticed your SSD slowing down and throwing SMART warnings, or if it\u2019s taking a long time to read certain files, don\u2019t ignore it. All of these are early signs that some of your SSD\u2019s blocks (memory cells) are starting to fail.<\/p>\n
At first, your SSD will quietly mark these areas as \u201cbad blocks\u201d and shift your data elsewhere using something known as reallocated sectors<\/strong>. But as the number of these bad blocks grows, you\u2019ll start seeing symptoms of SSD failure<\/a><\/strong> like corrupted files<\/strong>, SSD lag<\/strong>, or even missing data<\/strong>.<\/p>\n So buckle in as we explain what causes bad blocks and reallocated sectors in SSDs, how to check for them safely, and how Stellar SSD data recovery<\/a><\/strong> experts can help you recover data from an SSD with a large number of bad blocks and reallocated sectors.<\/p>\n Unlike a hard drive, where bad sectors are caused by damage to the platter<\/a><\/strong> surface, bad sectors on SSDs are formed by NAND cell wear-out from too many program\/erase cycles (or from voltage instability).<\/p>\n If that\u2019s too much jargon, let\u2019s simplify it. Unlike hard drives that use magnetic platters, your SSDs store information in NAND flash memory cells in the form of electrical charge. Data can be written to or deleted from these cells only a finite number of times (typically, 1000\u20133000).<\/p>\n Over time, as these cells wear out, they lose their ability to hold an electrical charge, and once that happens, the block becomes \u201cbad.\u201d So each time data is written to or erased from an SSD cell, it slightly wears down the cell, which eventually leads to bad blocks.<\/p>\n \ud83e\udde0 Note: <\/strong>At a deeper technical level, your SSD\u2019s controller uses a system called the Flash Translation Layer (FTL), which maps logical addresses to physical NAND cells. When this controller detects ECC (Error Correction Code) failures that exceed correction limits, the FTL can reallocate that address to a reserved spare block. Though this preserves your data\u2019s integrity, it also reduces the total available lifespan of the drive.<\/p>\n A few isolated bad blocks are normal, especially as your SSD ages. But if you notice your reallocated sector count rising consistently or SMART showing warnings like \u201cReallocation Event Count<\/strong>\u201d or \u201cUncorrectable Error Count<\/strong>,\u201d it\u2019s a clear sign that your SSD is wearing out faster than expected.<\/p><\/blockquote>\n Bad blocks don\u2019t just appear suddenly out of thin air\u2014they build up over time, and only when the SSD reallocated sector count gets too high do they give you problems. But there are some signs that your SSD will give you even before complete failure, and if you can catch these early symptoms, you can back up your data in time and send the drive for repair. These are the common symptoms of bad blocks on SSDs.<\/strong><\/p>\n \u26a0\ufe0f SMART warnings or health alerts:<\/strong> Your drive monitoring tools (like CrystalDiskInfo<\/strong> or the manufacturer\u2019s utility) show rising \u201cReallocated Block Count\u201d or \u201cPending Sector Count\u201d values. These are your SSD\u2019s early distress signals, but you have to do this SSD health check yourself to know.<\/p>\n \ud83d\udcc1 Files become unreadable or corrupt:<\/strong> Some of your files may refuse to open or can show unexpected read errors. This is especially true for larger ones stored in heavily used areas of the drive.<\/p>\n \ud83d\udd52 Slow read\/write operations:<\/strong> Copying or moving your data suddenly takes longer than usual, and the system responsiveness drops sharply when your SSD is under load.<\/p>\n \ud83d\udd04 Frequent retries or pauses:<\/strong> The controller keeps attempting to read failing cells before it eventually reassigns them, and this causes visible lag or system hangs.<\/p>\n \ud83d\udcbb Drive disappears intermittently:<\/strong> During intensive I\/O tasks, your SSD might disconnect momentarily and reappear after you restart. This is often due to firmware recovery loops.<\/p>\n \u26a0\ufe0f Caution: <\/strong>If any of these signs persist, it\u2019s very important that you stop unnecessary writes and back up your data immediately. Each new reallocation event means your SSD is nearing hardware-level failure.<\/p><\/blockquote>\n Read the next section to know what fixes you can try.<\/p>\n In cases of SSD showing bad blocks or reallocated sectors, you need to act early. And no, this doesn\u2019t mean that you rush to \u201crepair\u201d the drive. Instead, your focus should be on diagnosing the problem safely and preserving your data. Here\u2019s how you can do that.<\/strong><\/p>\n If your SMART data shows growing reallocated counts or bad block warnings, take it seriously. Copy all your essential data to another drive or cloud storage before you continue any diagnostics. The more you use your failing SSD, the faster the damage will spread.<\/p>\n Start with CrystalDiskInfo<\/strong> or your SSD manufacturer\u2019s utility. Specifically, look for these parameters: Reallocated Block Count<\/strong>, Uncorrectable Error Count<\/strong>, and Reallocation Event Count<\/strong>.<\/p>\n CrystalDiskInfo interface<\/p>\n If these numbers remain stable, keep monitoring them every month. But if they increase steadily, you can be sure that your SSD\u2019s NAND cells are wearing out.<\/p>\n Each SSD brand (Samsung, Crucial, Kingston, Sandisk, etc.) has its own tool to test for bad blocks and firmware issues. These tools often display the number of reallocated sectors and can perform surface scans without writing over your existing data.<\/p>\n After your data is safely backed up, you can try and update the firmware. Outdated firmware causes mismanaged wear leveling and block remapping. Visit your SSD manufacturer\u2019s official website to check for updates (type in \u201c[SSD brand name] firmware update\u201d on Google). Just make sure you don\u2019t interrupt this update process because a failed firmware flash can make your SSD unreadable.<\/strong><\/p>\n If the firmware update doesn\u2019t fix the issue, you might be tempted to try out full formats or zero-fill utilities online that claim to restore SSD function. Our advice\u2014don\u2019t!<\/p>\n These tools can accelerate failure because they rewrite data across every block, including weak ones. If your SSD already has bad blocks, these utilities can trigger more reallocation events and permanently erase data that would otherwise have been recoverable.<\/strong><\/p>\n We understand that this information can be a bit overwhelming for beginners, so we\u2019ve put together this quick reference table that helps you interpret what your SSD\u2019s SMART readings mean and what you should do next.<\/strong><\/p>\n\nRoot Causes of Bad Blocks and Reallocated Sectors in SSDs<\/strong><\/h2>\n
Common Symptoms of Bad Blocks or Reallocated Sectors<\/strong><\/h2>\n
SSD Bad Blocks and Reallocated Sectors\u2014Safe Fixes and Diagnostic Steps<\/strong><\/h2>\n
1. Back Up Immediately if Errors Appear<\/strong><\/h3>\n
2. Check the SMART Health Status<\/strong><\/h3>\n
3. Run the Manufacturer\u2019s Diagnostic Tool<\/strong><\/h3>\n
4. Update the Firmware<\/strong><\/h3>\n
5. Avoid Zero-Fill or Format Tools<\/strong><\/h3>\n