--- title: Synology's health check missed 9,527 errors on my drive,... description: A personal investigation into a 6-year-old Synology NAS reveals that the DSM dashboard reported a Toshiba hard drive as simply 'Healthy' despite the drive... canonical: https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Synology's health check missed 9,527 errors on my drive, and I only found them by asking directly | daily.dev og:description: A personal investigation into a 6-year-old Synology NAS reveals that the DSM dashboard reported a Toshiba hard drive as simply 'Healthy' despite the drive... og:url: https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l og:image: https://api.daily.dev/og/posts/QcgfaMD1L.png og:image:alt: Synology's health check missed 9,527 errors on my drive, and I only found them by asking directly og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Synology's health check missed 9,527 errors on my drive, and I only found them by asking directly **[XDA Developers](https://daily.dev/sources/xda-developers)** · 4 min read · 0 upvotes · 0 comments ## Summary A personal investigation into a 6-year-old Synology NAS reveals that the DSM dashboard reported a Toshiba hard drive as simply 'Healthy' despite the drive having logged 9,527 command errors. Using SSH and smartctl directly against the drive, the author found three of Backblaze's five recommended SMART attributes (5, 197, 198) were clean, two (187, 188) weren't reported by this drive at all, and a separate error log attribute (199) showed thousands of ICRC checksum errors that DSM never surfaced. The conclusion is that SMART health summaries from NAS dashboards can mask real degradation signals, so raw SMART data should supplement rather than replace a dashboard's health verdict. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Why does my Synology NAS show a drive as healthy when smartctl reports thousands of errors? Synology's DSM only surfaces a simplified pass/fail health label and doesn't display the full SMART attribute table, including error logs. A drive can report a clean status on attributes like 5, 197, and 198 while still accumulating thousands of command errors (attribute 199, including Interface CRC errors) that never appear in DSM's dashboard or history tab. _Anyone relying on dashboard health checks for aging drives can compare notes on SMART monitoring via daily.dev._ ### Which SMART attributes does Backblaze use to predict hard drive failure? Backblaze flags failing drives using five SMART attributes: 5 (reallocated sectors), 187 (reported uncorrectable errors), 188 (command timeout), 197 (pending sector count), and 198 (uncorrectable sector count). Not every drive reports all five; some models, like certain Toshiba HDDs, omit attributes 187 and 188 from their SMART table entirely. _Developers managing storage reliability can track SMART attribute discussions like this on daily.dev._ ### How do I check raw SMART data on a Synology NAS instead of just the health status? Enable SSH access on the NAS, connect over port 22 with a client such as Termius, and run smartctl -d sat -A /dev/sdb (substituting the correct device path) to pull the full SMART attribute table directly from the drive, bypassing DSM's simplified healthy/unhealthy summary. _Homelab builders troubleshooting NAS storage can find more hands-on fixes like this on daily.dev._ ## Similar posts on daily.dev - [One in four HDDs fail without any warning, and your NAS won't be able to tell you](https://daily.dev/posts/one-in-four-hdds-fail-without-any-warning-and-your-nas-won-t-be-able-to-tell-you-eaf0xklfb) · XDA Developers · 0 upvotes · 0 comments - [My homelab SSD was silently failing, and one monitoring tool caught it before the other](https://daily.dev/posts/my-homelab-ssd-was-silently-failing-and-one-monitoring-tool-caught-it-before-the-other-3y7m6quuv) · XDA Developers · 0 upvotes · 0 comments - [SMART Stats for Your SSD and HDD on Linux, macOS and Windows — Nick Janetakis](https://daily.dev/posts/smart-stats-for-your-ssd-and-hdd-on-linux-macos-and-windows-nick-janetakis-gs4xpa1vv) · Nick Janetakis · 0 upvotes · 0 comments - [Your SSD health may be "Good," but disk write errors mean you should start worrying sooner](https://daily.dev/posts/your-ssd-health-may-be-good-but-disk-write-errors-mean-you-should-start-worrying-sooner-anh0tiyom) · XDA Developers · 0 upvotes · 0 comments - [Backblaze Drive Stats for Q3 2025](https://daily.dev/posts/backblaze-drive-stats-for-q3-2025-yac6bblqa) · Hacker News · 0 upvotes · 0 comments --- [View this post on daily.dev](https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Synology's health check missed 9,527 errors on my drive, and I only found them by asking directly","url":"https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l"},"datePublished":"2026-10-01T21:06:13.458Z","dateModified":"2026-10-01T21:10:40.851Z","description":"A personal investigation into a 6-year-old Synology NAS reveals that the DSM dashboard reported a Toshiba hard drive as simply 'Healthy' despite the drive...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/9c59c8e10f44c6b76257ec4216129e35?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/9c59c8e10f44c6b76257ec4216129e35?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"XDA Developers","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"XDA Developers","logo":"https://media.daily.dev/image/upload/s--kCg6yyAP--/f_auto,q_auto/v1774964407/logos/xda-developers?_a=BAMAMiWQ0","url":"https://daily.dev/sources/xda-developers"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"","timeRequired":"PT4M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"XDA Developers","item":"https://daily.dev/sources/xda-developers"},{"@type":"ListItem","position":3,"name":"Synology's health check missed 9,527 errors on my drive, and I only found them by asking directly"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/synology-s-health-check-missed-9-527-errors-on-my-drive-and-i-only-found-them-by-asking-directly-qcgfamd1l#faq","mainEntity":[{"@type":"Question","name":"Why does my Synology NAS show a drive as healthy when smartctl reports thousands of errors?","acceptedAnswer":{"@type":"Answer","text":"Synology's DSM only surfaces a simplified pass/fail health label and doesn't display the full SMART attribute table, including error logs. A drive can report a clean status on attributes like 5, 197, and 198 while still accumulating thousands of command errors (attribute 199, including Interface CRC errors) that never appear in DSM's dashboard or history tab. Anyone relying on dashboard health checks for aging drives can compare notes on SMART monitoring via daily.dev."}},{"@type":"Question","name":"Which SMART attributes does Backblaze use to predict hard drive failure?","acceptedAnswer":{"@type":"Answer","text":"Backblaze flags failing drives using five SMART attributes: 5 (reallocated sectors), 187 (reported uncorrectable errors), 188 (command timeout), 197 (pending sector count), and 198 (uncorrectable sector count). Not every drive reports all five; some models, like certain Toshiba HDDs, omit attributes 187 and 188 from their SMART table entirely. 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