lhubert
/
base-de-connaissances


			
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348
							<!DOCTYPE html>
<html lang="en"><head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<meta name="viewport" content="width=device-width, initial-scale=1.0">

<link rel="apple-touch-icon" sizes="180x180" href="https://techoverflow.net/favicon-180x180.png">
<link rel="icon" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/TechOverflow.svg">
<link rel="icon" type="image/png" sizes="192x192" href="https://techoverflow.net/favicon-192x192.png">
<link rel="icon" type="image/png" sizes="32x32" href="https://techoverflow.net/favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="https://techoverflow.net/favicon-16x16.png">

<link rel="manifest" href="https://techoverflow.net/techoverflow.webmanifest">

<meta name="msapplication-TileColor" content="#da532c">
<meta name="theme-color" content="#ffffff">
<title itemprop="name"> How to interpret smartctl messages like ‘Error: UNC at LBA’? | TechOverflow 
</title>
<meta name="description" content="Based in Munich, our engineers &amp; laboratory helps you to develop your product from the first idea to certification &amp; production.">
<meta property="og:title" content="How to interpret smartctl messages like ‘Error: UNC at LBA’? | TechOverflow">
<meta name="twitter:title" content="How to interpret smartctl messages like ‘Error: UNC at LBA’? | TechOverflow">
<meta itemprop="name" content="How to interpret smartctl messages like ‘Error: UNC at LBA’? | TechOverflow">
<meta name="application-name" content="How to interpret smartctl messages like ‘Error: UNC at LBA’? | TechOverflow">
<meta property="og:description" content="Based in Munich, our engineers &amp; laboratory helps you to develop your product from the first idea to certification &amp; production.">
<meta property="og:site_name" content="TechOverflow">
<meta property="og:url" content="https://techoverflow.net/2016/07/25/how-to-interpret-smartctl-messages-like-error-unc-at-lba/">
<meta property="og:locale" content="en">
<meta property="og:image" content="/images/tailbliss-cover.png">
<meta property="og:image:secure_url" content="https://techoverflow.net/images/tailbliss-cover.png">
<meta property="og:type" content="article">

<script>
    
    if (localStorage.getItem('color-theme') === 'dark' || (!('color-theme' in localStorage) && window.matchMedia('(prefers-color-scheme: dark)').matches)) {
        document.documentElement.classList.add('dark');
    } else {
        document.documentElement.classList.remove('dark')
    }
</script>


<link rel="stylesheet" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/style.min.9a429de0074bb03b54a5dae5ec7013170c72f4d11103257e4b.css" integrity="sha256-mkKd4AdLsDtUpdrl7HATFwxy9NERAyV+SxrgmF5S2j0=">

<link rel="stylesheet" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/techoverflow.css"><link rel="stylesheet" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/kicad.css"><link rel="stylesheet" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/donate.css"><link rel="stylesheet" href="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/docsearch.css">
</head>

<body class="bg-zinc-100 dark:bg-gray-800">
    <div class="top-0 z-50 w-full text-gray-200 bg-gray-900 border-2 border-gray-900 md:sticky border-b-stone-200/10">
    <div x-data="{ open: false }" class="flex flex-col max-w-full px-4 mx-auto md:items-center md:justify-between md:flex-row md:px-6 lg:px-8">
        <div class="flex flex-row items-center justify-between p-4">
            <a href="https://techoverflow.net/" class="flex text-gray-100 transition duration-1000 ease-in-out group">
                <img src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/TechOverflow.svg" class="transition-opacity h-9 w-9 group-hover:opacity-50 group-focus:opacity-70" alt="TechOverflow Logo">
                <div class="mt-1 ml-3 text-xl font-black tracking-tight text-gray-100 transition-colors group-hover:text-gray-400/60">
                    TechOverflow</div>
            </a>
            <button class="rounded-lg md:hidden focus:outline-none focus:shadow-outline" @click="open = !open" role="navigation" aria-expanded="false" aria-label="Main" aria-controls="menuItems">
                <svg fill="currentColor" viewBox="0 0 20 20" class="w-6 h-6">
                    <path x-show="!open" fill-rule="evenodd" d="M3 5a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1zM3 10a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1zM9 15a1 1 0 011-1h6a1 1 0 110 2h-6a1 1 0 01-1-1z" clip-rule="evenodd"></path>
                    <path x-show="open" fill-rule="evenodd" d="M4.293 4.293a1 1 0 011.414 0L10 8.586l4.293-4.293a1 1 0 111.414 1.414L11.414 10l4.293 4.293a1 1 0 01-1.414 1.414L10 11.414l-4.293 4.293a1 1 0 01-1.414-1.414L8.586 10 4.293 5.707a1 1 0 010-1.414z" clip-rule="evenodd" style="display: none;"></path>
                </svg>
            </button>
        </div>
        <nav :class="{'flex': open, 'hidden': !open}" class="flex-col flex-grow hidden pb-4 md:pb-0 md:flex md:justify-end md:flex-row">
            
            <div id="search"><button type="button" aria-label="Search (Command+K)" class="DocSearch DocSearch-Button"><span class="DocSearch-Button-Container"><svg width="20" height="20" viewBox="0 0 20 20" aria-hidden="true" class="DocSearch-Search-Icon"><path d="M14.386 14.386l4.0877 4.0877-4.0877-4.0877c-2.9418 2.9419-7.7115 2.9419-10.6533 0-2.9419-2.9418-2.9419-7.7115 0-10.6533 2.9418-2.9419 7.7115-2.9419 10.6533 0 2.9419 2.9418 2.9419 7.7115 0 10.6533z" stroke="currentColor" fill="none" fill-rule="evenodd" stroke-linecap="round" stroke-linejoin="round"></path></svg><span class="DocSearch-Button-Placeholder">Search</span></span><span class="DocSearch-Button-Keys"><kbd class="DocSearch-Button-Key DocSearch-Button-Key--pressed">⌘</kbd><kbd class="DocSearch-Button-Key">K</kbd></span></button></div>
            
            
            <a class="px-4 py-2 mt-2 text-sm font-semibold rounded-lg md:mt-0 md:ml-4 hover:text-white focus:text-white hover:bg-primary-600 focus:bg-primary-700 focus:outline-none focus:shadow-outline" href="https://techoverflow.net/" title="Consulting">
                Consulting
            </a>
            
            
            <a class="px-4 py-2 mt-2 text-sm font-semibold rounded-lg md:mt-0 md:ml-4 hover:text-white focus:text-white hover:bg-primary-600 focus:bg-primary-700 focus:outline-none focus:shadow-outline" href="https://techoverflow.net/blog" title="Blog">
                Blog
            </a>
            
            
            <a class="px-4 py-2 mt-2 text-sm font-semibold rounded-lg md:mt-0 md:ml-4 hover:text-white focus:text-white hover:bg-primary-600 focus:bg-primary-700 focus:outline-none focus:shadow-outline" href="https://techoverflow.net/" title="Tools">
                Tools
            </a>
            
            
            <button id="theme-toggle" type="button" class="p-2 text-sm text-gray-500 rounded-lg md: dark:text-gray-400 hover:bg-gray-100 dark:hover:bg-gray-700 focus:outline-none focus:ring-4 focus:ring-gray-200 dark:focus:ring-gray-700 md:ml-2 max-w-5 xs:hidden">
                <svg id="theme-toggle-dark-icon" class="w-5 h-5" fill="currentColor" viewBox="0 0 20 20" xmlns="http://www.w3.org/2000/svg">
                    <path d="M17.293 13.293A8 8 0 016.707 2.707a8.001 8.001 0 1010.586 10.586z">
                    </path>
                </svg>
                <svg id="theme-toggle-light-icon" class="hidden w-5 h-5" fill="currentColor" viewBox="0 0 20 20" aria-label="Dark or Light Mode" xmlns="http://www.w3.org/2000/svg">
                    <path d="M10 2a1 1 0 011 1v1a1 1 0 11-2 0V3a1 1 0 011-1zm4 8a4 4 0 11-8 0 4 4 0 018 0zm-.464 4.95l.707.707a1 1 0 001.414-1.414l-.707-.707a1 1 0 00-1.414 1.414zm2.12-10.607a1 1 0 010 1.414l-.706.707a1 1 0 11-1.414-1.414l.707-.707a1 1 0 011.414 0zM17 11a1 1 0 100-2h-1a1 1 0 100 2h1zm-7 4a1 1 0 011 1v1a1 1 0 11-2 0v-1a1 1 0 011-1zM5.05 6.464A1 1 0 106.465 5.05l-.708-.707a1 1 0 00-1.414 1.414l.707.707zm1.414 8.486l-.707.707a1 1 0 01-1.414-1.414l.707-.707a1 1 0 011.414 1.414zM4 11a1 1 0 100-2H3a1 1 0 000 2h1z" fill-rule="evenodd" clip-rule="evenodd"></path>
                </svg>
            </button>
            
        </nav>
    </div>
</div>
    
<article>
  <header class="mb-4 bg-primary-600">
    <span class="py-96">
      <h1 class="py-16 text-5xl font-black text-center text-white">
        How to interpret smartctl messages like ‘Error: UNC at LBA’?
      </h1>
    </span>
  </header>
  <div class="max-w-4xl mx-auto mt-8 mb-2">
    <div class="px-6">
      
    </div>
  </div>
  
  <div class="max-w-4xl px-6 pt-6 pb-16 mx-auto prose dark:prose-invert dark:text-white">
    <p>When running <a href="https://www.smartmontools.org/"><code>smartctl</code></a>
 on your hard drive, you often get a plethora of information that can be
 hard to interpret for unexperienced users. This post attempts to 
provide aid in interpreting what the technical reasons behind the error 
messages are. If you’re looking for advice on whether to replace your 
hard drive, the only guidance I can give you is <em>it might fail any time, so better backup your data, but it might also run for many years to come.</em>. Furthermore, this article does not describe basic SMART <code>WHEN_FAILED</code> checking but rather interpretation of more subtle signs of possibly impending HDD&nbsp;failures.</p>
<p>One example that is particularly hard to interpret is the device error log storing the last few errors, for&nbsp;example</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>Error 8910 occurred at disk power-on lifetime: 7257 hours (302 days + 9 hours)
</span></span><span style="display:flex;"><span>  When the command that caused the error occurred, the device was active or idle.
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span>  After command completion occurred, registers were:
</span></span><span style="display:flex;"><span>  ER ST SC SN CL CH DH
</span></span><span style="display:flex;"><span>  -- -- -- -- -- -- --
</span></span><span style="display:flex;"><span>  40 41 1a 00 33 96 61  Error: UNC at LBA = 0x01963300 = 26620672
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span>  Commands leading to the command that caused the error were:
</span></span><span style="display:flex;"><span>  CR FR SC SN CL CH DH DC   Powered_Up_Time  Command/Feature_Name
</span></span><span style="display:flex;"><span>  -- -- -- -- -- -- -- --  ----------------  --------------------
</span></span><span style="display:flex;"><span>  60 08 18 00 33 96 40 00      03:09:52.125  READ FPDMA QUEUED
</span></span><span style="display:flex;"><span>  60 88 10 50 06 11 40 00      03:09:52.125  READ FPDMA QUEUED
</span></span><span style="display:flex;"><span>  60 08 08 60 ac 5e 40 00      03:09:52.113  READ FPDMA QUEUED
</span></span><span style="display:flex;"><span>  60 08 00 48 cf 6d 40 00      03:09:52.099  READ FPDMA QUEUED
</span></span><span style="display:flex;"><span>  60 90 f0 b0 ef e5 40 00      03:09:52.065  READ FPDMA QUEUED
</span></span></code></pre></div><p>Obviously, the first line shows when
 this error occured. The other lines, however, are not as obvious. Let’s
 examine the next&nbsp;section:</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>After command completion occurred, registers were:
</span></span><span style="display:flex;"><span>ER ST SC SN CL CH DH
</span></span><span style="display:flex;"><span>-- -- -- -- -- -- --
</span></span><span style="display:flex;"><span>40 41 1a 00 33 96 61  Error: UNC at LBA = 0x01963300 = 26620672
</span></span></code></pre></div><p>While this section also shows the 
content of some registers while the error occured, the interesting part 
of it is the error description <code>Error:</code> <code>UNC</code> <code>at</code> <code>LBA</code> <code>= 0x01963300 =&nbsp;26620672.</code></p>
<p>A <a href="https://www.smartmontools.org/wiki/Howto_ReadSmartctlReports_ATA_542.1#LBA">LBA</a> is a <em>logical block address</em>, i.e. some logical address on the hard drive. It is shown in both hexadecimal form <code>0x01963300</code> and in decimal form <code>26620672</code>. In order to convert it to a byte address, you need to multiply it by the value listed at the head of the <code>smartctl</code>output:</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>Sector Size:      512 bytes logical/physical
</span></span></code></pre></div><p>In almost any case, this value is 512 bytes, so in this example the byte offset would be <code>26620672 * 512 = 13629784064 = 12.69 GiB</code>. In some cases it might be helpful to look up this address in a tool like <a href="http://gparted.org/">GParted</a> to see in which partition the error occured in. Also see <a href="https://www.smartmontools.org/browser/trunk/www/badblockhowto.xml#e2_example1">this smartmontools HOWTO</a> describing this process in&nbsp;detail.</p>
<h3 id="uncerrors">UNC&nbsp;errors</h3>
<p>The error message now tells us than an error called <code>UNC</code> occured at this LBA. <a href="https://www.smartmontools.org/wiki/Howto_ReadSmartctlReports_ATA_542.1#UNC">UNC</a> is shorthand for <em>UNCorrectable</em>, which means <em>the data which has been read from the hard drive at this LBA was damaged and could not be corrected</em>.</p>
<p>Hard drives not only store your data by itself, but automatically compute a so-called <em>error-correction code</em> (<a href="https://en.wikipedia.org/wiki/Error-correcting_code">ECC</a>).
 While there are many subtypes of those mathematical codes, they have 
one aspect in common: Given a set of bytes (e.g. the ones stored on the 
hard drive) which might be slightly damaged (i.e. some 0-bits are now-1 
bits or vice versa) and and the matching ECC code (constituting of a few
 extra bytes) a suitable decoder can recover a limited number of bit 
errors. In most cases, ECC codes can also detect errors - for example, 
one specific ECC code might be able to correct one bit flip in two 
bytes, but it can detect up to three bitflips in two&nbsp;bytes.</p>
<p>If there are more bitflips than the ECC can recover (but not more 
than it can detect), this results in an unrecoverable error - the UNC. 
If there are more bitflips than the ECC can detect, anything might 
happen: Usually, the data that is computed from the ECC will be damaged,
 or no error might be detected at&nbsp;all.</p>
<p>Note that this explanation is highly simplified. For example, ECC 
codes are not stored as bytes separate from the data, but instead a 
mathematical function is computed on the data, resulting in a set of 
bytes that is larger that the original dataset - containing both the 
data itself plus the error-recovery extra data. In other words, the ECC 
data plus the data itself are mixed&nbsp;together.</p>
<p>This has multiple consequences for the interpretation. Firstly, this 
means that physically the data could be read, yet it does not seem to be
 correct. This&nbsp;means</p>
<h3 id="other-errormessages">Other error&nbsp;messages</h3>
<p>While <em>UNC</em> errors occur reasonably often, there are other, more rare errors that you can’t find too much documentation&nbsp;about.</p>
<p>There is one definitive source for all <code>smartctl</code> error messages: The <code>smartmontools</code> <a href="http://builds.smartmontools.org/">source code</a>.</p>
<p>We can find the error descriptions in <code>ataprint.cpp</code> (also see the GPL license information in the source&nbsp;tarball):</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-c" data-lang="c"><span style="display:flex;"><span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>  <span style="color:#f92672">*</span>abrt  <span style="color:#f92672">=</span> <span style="color:#e6db74">"ABRT"</span>;  <span style="color:#75715e">// ABORTED
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>amnf  <span style="color:#f92672">=</span> <span style="color:#e6db74">"AMNF"</span>;  <span style="color:#75715e">// ADDRESS MARK NOT FOUND
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>ccto  <span style="color:#f92672">=</span> <span style="color:#e6db74">"CCTO"</span>;  <span style="color:#75715e">// COMMAND COMPLETION TIMED OUT
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>eom   <span style="color:#f92672">=</span> <span style="color:#e6db74">"EOM"</span>;   <span style="color:#75715e">// END OF MEDIA
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>icrc  <span style="color:#f92672">=</span> <span style="color:#e6db74">"ICRC"</span>;  <span style="color:#75715e">// INTERFACE CRC ERROR
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>idnf  <span style="color:#f92672">=</span> <span style="color:#e6db74">"IDNF"</span>;  <span style="color:#75715e">// ID NOT FOUND
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>ili   <span style="color:#f92672">=</span> <span style="color:#e6db74">"ILI"</span>;   <span style="color:#75715e">// MEANING OF THIS BIT IS COMMAND-SET SPECIFIC
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>mc    <span style="color:#f92672">=</span> <span style="color:#e6db74">"MC"</span>;    <span style="color:#75715e">// MEDIA CHANGED 
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>mcr   <span style="color:#f92672">=</span> <span style="color:#e6db74">"MCR"</span>;   <span style="color:#75715e">// MEDIA CHANGE REQUEST
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>nm    <span style="color:#f92672">=</span> <span style="color:#e6db74">"NM"</span>;    <span style="color:#75715e">// NO MEDIA
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>obs   <span style="color:#f92672">=</span> <span style="color:#e6db74">"obs"</span>;   <span style="color:#75715e">// OBSOLETE
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>tk0nf <span style="color:#f92672">=</span> <span style="color:#e6db74">"TK0NF"</span>; <span style="color:#75715e">// TRACK 0 NOT FOUND
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>unc   <span style="color:#f92672">=</span> <span style="color:#e6db74">"UNC"</span>;   <span style="color:#75715e">// UNCORRECTABLE
</span></span></span><span style="display:flex;"><span><span style="color:#75715e"></span><span style="color:#66d9ef">const</span> <span style="color:#66d9ef">char</span>   <span style="color:#f92672">*</span>wp    <span style="color:#f92672">=</span> <span style="color:#e6db74">"WP"</span>;    <span style="color:#75715e">// WRITE PROTECTED
</span></span></span></code></pre></div><p>Realistically, you’ll only 
encounter a few of these errors even if you are working with hard disks 
professionally. Some of these errors like <code>MC</code>, <code>MCR</code> or <code>NM</code>
 are also related to hot-swapping of hard drives and do not neccessarily
 represent errors related to hard drive health&nbsp;itself.</p>
<p>One important error is <code>ICRC</code> - the interface CRC error. 
This means that there are errors being detected on the IDE/SATA or PCIe 
bus the hard drive is connected to. Although this is rare and might be 
caused by the HDD itself, it might mean that your chipset (the hardware 
controlling e.g. SATA) is damaged - in this case, replacing the hard 
drive would not fix the issue. Possibly there is also an intermittent 
cable&nbsp;connection.</p>
<h3 id="how-severe-are-thoseerrors">How severe are those&nbsp;errors?</h3>
<p>Over the life of most hard drives, especially consumer models, errors
 will occur - more often so in portable devices where high acceleration 
forces are more like to be&nbsp;encountered.</p>
<p>What separates a good hard drive from one at the end of its life 
(excluding those that fail without warning) is often the frequency of 
new errors. If you look at the total lifetime of the HDD, i.e. <code>Power_On_Hours</code> or&nbsp;similar:</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>9 Power_On_Hours          0x0032   082   082   000    Old_age   Always       -       8586
</span></span></code></pre></div><p>and compare the value (in this case <code>8586</code>) with the lifetime at the last&nbsp;error,</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>Error 8911 occurred at disk power-on lifetime: 7257 hours
</span></span></code></pre></div><p>in this case, <code>7257</code>, you
 can see over a thousand HDD operational hours have passed since the 
last error. This indicates that there is no mechanical defect which 
could result in destruction of the hard drive but rather a couple of 
defective or damaged sectors. UNC errors do not even neccessarily mean 
that the sectors are physically&nbsp;damaged.</p>
<p>Often hard drive errors are triggered when a files that are accessed 
very rarely (such as archived video files that are only opened every few
 years). When there are enough bit flips in such files for any reason, 
this can result in a larger number of HDD errors appearing at&nbsp;once.</p>
<p>Another indicator is the total number of errors the hard drive has encountered, i.e. <code>8911</code> in</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>Error 8911 occurred at disk power-on lifetime: 7257 hours
</span></span></code></pre></div><p>or&nbsp;in</p>
<div class="highlight"><pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;"><code class="language-plaintext" data-lang="plaintext"><span style="display:flex;"><span>ATA Error Count: 8911 (device log contains only the most recent five errors)
</span></span></code></pre></div><p>While this number is not shown for 
all hard drives, a very high number or a number which is growing rapidly
 indicates there is some physical issue with the drive. Issues relating 
to only a few bad sectors induce a sudden jump in the error counter, but
 after that. Note, however, that there can be other reasons for a high 
error counter, for example a bad or intermittent physical connection to 
the hard&nbsp;drive.</p>
<p>Also see <a href="https://techoverflow.net/2015/01/07/fixing-bad-blocks-on-hdds-using-fixhdd.py/">this previous post</a> on how to fix bad HDD&nbsp;sectors.</p>

    <hr class="after-content">
    <div class="donate">
      <div class="donate-text">
        If this post helped you, please consider buying me a coffee or 
donating via PayPal to support research &amp; publishing of new posts on
 TechOverflow
      </div>
      
      <div class="bmc-btn-container">
        <a class="bmc-btn" target="_blank" href="http://buymeacoffee.com/ulikoehler">
          <svg viewBox="0 0 884 1279" fill="none" xmlns="http://www.w3.org/2000/svg">
            <path d="M791.109 297.518L790.231 297.002L788.201 296.383C789.018 297.072 790.04 297.472 791.109 297.518Z" fill="#0D0C22"></path>
            <path d="M803.896 388.891L802.916 389.166L803.896 388.891Z" fill="#0D0C22"></path>
            <path d="M791.484 297.377C791.359 297.361 791.237 297.332 791.118 297.29C791.111 297.371 791.111 297.453 791.118 297.534C791.252 297.516 791.379 297.462 791.484 297.377Z" fill="#0D0C22"></path>
            <path d="M791.113 297.529H791.244V297.447L791.113 297.529Z" fill="#0D0C22"></path>
            <path d="M803.111 388.726L804.591 387.883L805.142 387.573L805.641 387.04C804.702 387.444 803.846 388.016 803.111 388.726Z" fill="#0D0C22"></path>
            <path d="M793.669 299.515L792.223 298.138L791.243 297.605C791.77 298.535 792.641 299.221 793.669 299.515Z" fill="#0D0C22"></path>
            <path d="M430.019 1186.18C428.864 1186.68 427.852 1187.46 427.076 1188.45L427.988 1187.87C428.608 1187.3 429.485 1186.63 430.019 1186.18Z" fill="#0D0C22"></path>
            <path d="M641.187 1144.63C641.187 1143.33 640.551 1143.57 640.705 1148.21C640.705 1147.84 640.86 1147.46 640.929 1147.1C641.015 1146.27 641.084 1145.46 641.187 1144.63Z" fill="#0D0C22"></path>
            <path d="M619.284 1186.18C618.129 1186.68 617.118 1187.46 616.342 1188.45L617.254 1187.87C617.873 1187.3 618.751 1186.63 619.284 1186.18Z" fill="#0D0C22"></path>
            <path d="M281.304 1196.06C280.427 1195.3 279.354 1194.8 278.207 1194.61C279.136 1195.06 280.065 1195.51 280.684 1195.85L281.304 1196.06Z" fill="#0D0C22"></path>
            <path d="M247.841 1164.01C247.704 1162.66 247.288 1161.35 246.619 1160.16C247.093 1161.39 247.489 1162.66 247.806 1163.94L247.841 1164.01Z" fill="#0D0C22"></path>
            <path class="logo-coffee" d="M472.623 590.836C426.682 610.503 374.546 632.802 306.976 632.802C278.71 632.746 250.58 628.868 223.353 621.274L270.086 1101.08C271.74 1121.13 280.876 1139.83 295.679 1153.46C310.482 1167.09 329.87 1174.65 349.992 1174.65C349.992 1174.65 416.254 1178.09 438.365 1178.09C462.161 1178.09 533.516 1174.65 533.516 1174.65C553.636 1174.65 573.019 1167.08 587.819 1153.45C602.619 1139.82 611.752 1121.13 613.406 1101.08L663.459 570.876C641.091 563.237 618.516 558.161 593.068 558.161C549.054 558.144 513.591 573.303 472.623 590.836Z" fill="#FFDD00"></path>
            <path d="M78.6885 386.132L79.4799 386.872L79.9962 387.182C79.5987 386.787 79.1603 386.435 78.6885 386.132Z" fill="#0D0C22"></path>
            <path class="logo-outline" d="M879.567 341.849L872.53 306.352C866.215 274.503 851.882 244.409 819.19 232.898C808.711 229.215 796.821 227.633 788.786 220.01C780.751 212.388 778.376 200.55 776.518 189.572C773.076 169.423 769.842 149.257 766.314 129.143C763.269 111.85 760.86 92.4243 752.928 76.56C742.604 55.2584 721.182 42.8009 699.88 34.559C688.965 30.4844 677.826 27.0375 666.517 24.2352C613.297 10.1947 557.342 5.03277 502.591 2.09047C436.875 -1.53577 370.983 -0.443234 305.422 5.35968C256.625 9.79894 205.229 15.1674 158.858 32.0469C141.91 38.224 124.445 45.6399 111.558 58.7341C95.7448 74.8221 90.5829 99.7026 102.128 119.765C110.336 134.012 124.239 144.078 138.985 150.737C158.192 159.317 178.251 165.846 198.829 170.215C256.126 182.879 315.471 187.851 374.007 189.968C438.887 192.586 503.87 190.464 568.44 183.618C584.408 181.863 600.347 179.758 616.257 177.304C634.995 174.43 647.022 149.928 641.499 132.859C634.891 112.453 617.134 104.538 597.055 107.618C594.095 108.082 591.153 108.512 588.193 108.942L586.06 109.252C579.257 110.113 572.455 110.915 565.653 111.661C551.601 113.175 537.515 114.414 523.394 115.378C491.768 117.58 460.057 118.595 428.363 118.647C397.219 118.647 366.058 117.769 334.983 115.722C320.805 114.793 306.661 113.611 292.552 112.177C286.134 111.506 279.733 110.801 273.333 110.009L267.241 109.235L265.917 109.046L259.602 108.134C246.697 106.189 233.792 103.953 221.025 101.251C219.737 100.965 218.584 100.249 217.758 99.2193C216.932 98.1901 216.482 96.9099 216.482 95.5903C216.482 94.2706 216.932 92.9904 217.758 91.9612C218.584 90.9319 219.737 90.2152 221.025 89.9293H221.266C232.33 87.5721 243.479 85.5589 254.663 83.8038C258.392 83.2188 262.131 82.6453 265.882 82.0832H265.985C272.988 81.6186 280.026 80.3625 286.994 79.5366C347.624 73.2301 408.614 71.0801 469.538 73.1014C499.115 73.9618 528.676 75.6996 558.116 78.6935C564.448 79.3474 570.746 80.0357 577.043 80.8099C579.452 81.1025 581.878 81.4465 584.305 81.7391L589.191 82.4445C603.438 84.5667 617.61 87.1419 631.708 90.1703C652.597 94.7128 679.422 96.1925 688.713 119.077C691.673 126.338 693.015 134.408 694.649 142.03L696.732 151.752C696.786 151.926 696.826 152.105 696.852 152.285C701.773 175.227 706.7 198.169 711.632 221.111C711.994 222.806 712.002 224.557 711.657 226.255C711.312 227.954 710.621 229.562 709.626 230.982C708.632 232.401 707.355 233.6 705.877 234.504C704.398 235.408 702.75 235.997 701.033 236.236H700.895L697.884 236.649L694.908 237.044C685.478 238.272 676.038 239.419 666.586 240.486C647.968 242.608 629.322 244.443 610.648 245.992C573.539 249.077 536.356 251.102 499.098 252.066C480.114 252.57 461.135 252.806 442.162 252.771C366.643 252.712 291.189 248.322 216.173 239.625C208.051 238.662 199.93 237.629 191.808 236.58C198.106 237.389 187.231 235.96 185.029 235.651C179.867 234.928 174.705 234.177 169.543 233.397C152.216 230.798 134.993 227.598 117.7 224.793C96.7944 221.352 76.8005 223.073 57.8906 233.397C42.3685 241.891 29.8055 254.916 21.8776 270.735C13.7217 287.597 11.2956 305.956 7.64786 324.075C4.00009 342.193 -1.67805 361.688 0.472751 380.288C5.10128 420.431 33.165 453.054 73.5313 460.35C111.506 467.232 149.687 472.807 187.971 477.556C338.361 495.975 490.294 498.178 641.155 484.129C653.44 482.982 665.708 481.732 677.959 480.378C681.786 479.958 685.658 480.398 689.292 481.668C692.926 482.938 696.23 485.005 698.962 487.717C701.694 490.429 703.784 493.718 705.08 497.342C706.377 500.967 706.846 504.836 706.453 508.665L702.633 545.797C694.936 620.828 687.239 695.854 679.542 770.874C671.513 849.657 663.431 928.434 655.298 1007.2C653.004 1029.39 650.71 1051.57 648.416 1073.74C646.213 1095.58 645.904 1118.1 641.757 1139.68C635.218 1173.61 612.248 1194.45 578.73 1202.07C548.022 1209.06 516.652 1212.73 485.161 1213.01C450.249 1213.2 415.355 1211.65 380.443 1211.84C343.173 1212.05 297.525 1208.61 268.756 1180.87C243.479 1156.51 239.986 1118.36 236.545 1085.37C231.957 1041.7 227.409 998.039 222.9 954.381L197.607 711.615L181.244 554.538C180.968 551.94 180.693 549.376 180.435 546.76C178.473 528.023 165.207 509.681 144.301 510.627C126.407 511.418 106.069 526.629 108.168 546.76L120.298 663.214L145.385 904.104C152.532 972.528 159.661 1040.96 166.773 1109.41C168.15 1122.52 169.44 1135.67 170.885 1148.78C178.749 1220.43 233.465 1259.04 301.224 1269.91C340.799 1276.28 381.337 1277.59 421.497 1278.24C472.979 1279.07 524.977 1281.05 575.615 1271.72C650.653 1257.95 706.952 1207.85 714.987 1130.13C717.282 1107.69 719.576 1085.25 721.87 1062.8C729.498 988.559 737.115 914.313 744.72 840.061L769.601 597.451L781.009 486.263C781.577 480.749 783.905 475.565 787.649 471.478C791.392 467.391 796.352 464.617 801.794 463.567C823.25 459.386 843.761 452.245 859.023 435.916C883.318 409.918 888.153 376.021 879.567 341.849ZM72.4301 365.835C72.757 365.68 72.1548 368.484 71.8967 369.792C71.8451 367.813 71.9483 366.058 72.4301 365.835ZM74.5121 381.94C74.6842 381.819 75.2003 382.508 75.7337 383.334C74.925 382.576 74.4089 382.009 74.4949 381.94H74.5121ZM76.5597 384.641C77.2996 385.897 77.6953 386.689 76.5597 384.641V384.641ZM80.672 387.979H80.7752C80.7752 388.1 80.9645 388.22 81.0333 388.341C80.9192 388.208 80.7925 388.087 80.6548 387.979H80.672ZM800.796 382.989C793.088 390.319 781.473 393.726 769.996 395.43C641.292 414.529 510.713 424.199 380.597 419.932C287.476 416.749 195.336 406.407 103.144 393.382C94.1102 392.109 84.3197 390.457 78.1082 383.798C66.4078 371.237 72.1548 345.944 75.2003 330.768C77.9878 316.865 83.3218 298.334 99.8572 296.355C125.667 293.327 155.64 304.218 181.175 308.09C211.917 312.781 242.774 316.538 273.745 319.36C405.925 331.405 540.325 329.529 671.92 311.91C695.906 308.686 719.805 304.941 743.619 300.674C764.835 296.871 788.356 289.731 801.175 311.703C809.967 326.673 811.137 346.701 809.778 363.615C809.359 370.984 806.139 377.915 800.779 382.989H800.796Z" fill="#0D0C22"></path>
          </svg>
          <span class="bmc-btn-text">Buy me a coffee</span>
        </a>
      </div>
      <div class="paypal-container">
        <form action="https://www.paypal.com/donate" method="post" target="_top">
          <input type="hidden" name="hosted_button_id" value="YZ3ZAU2GV952Y"><br>
          <input type="image" src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/PayPal-Donate.gif" border="0" name="submit" title="Donate to TechOverflow using PayPal" alt="Donate with PayPal button"><br>
        </form>
      </div>
    </div>
  </div>
</article>

    
<script defer="defer" src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/cdn.min.js"></script>

<script src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/darkmode.js" defer="defer"></script>
<footer class="bg-gray-900">
    <div class="max-w-md px-4 py-12 mx-auto overflow-hidden sm:max-w-3xl sm:px-6 lg:max-w-7xl lg:px-8">
        <nav class="flex flex-wrap justify-center -mx-5 -my-2" aria-label="Footer">
            
            <div class="px-5 py-2">
                <a href="https://techoverflow.net/impressum-datenschutz/" class="text-base text-gray-400 hover:text-gray-300">Impressum &amp; Datenschutz</a>
            </div>
            
        </nav>
        <div class="flex justify-center mt-8 space-x-6">
            
            <a href="#" class="text-gray-400 hover:text-gray-300">
                <span class="sr-only">Facebook</span>
                <svg class="w-6 h-6" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
                    <path fill-rule="evenodd" d="M22 12c0-5.523-4.477-10-10-10S2 6.477 2 12c0 4.991 3.657 9.128 8.438 9.878v-6.987h-2.54V12h2.54V9.797c0-2.506 1.492-3.89 3.777-3.89 1.094 0 2.238.195 2.238.195v2.46h-1.26c-1.243 0-1.63.771-1.63 1.562V12h2.773l-.443 2.89h-2.33v6.988C18.343 21.128 22 16.991 22 12z" clip-rule="evenodd"></path>
                </svg>
            </a>
            
            
            <a href="#" class="text-gray-400 hover:text-gray-300">
                <span class="sr-only">Instagram</span>
                <svg class="w-6 h-6" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
                    <path fill-rule="evenodd" d="M12.315 2c2.43 0 2.784.013 3.808.06 1.064.049 1.791.218 2.427.465a4.902 4.902 0 011.772 1.153 4.902 4.902 0 011.153 1.772c.247.636.416 1.363.465 2.427.048 1.067.06 1.407.06 4.123v.08c0 2.643-.012 2.987-.06 4.043-.049 1.064-.218 1.791-.465 2.427a4.902 4.902 0 01-1.153 1.772 4.902 4.902 0 01-1.772 1.153c-.636.247-1.363.416-2.427.465-1.067.048-1.407.06-4.123.06h-.08c-2.643 0-2.987-.012-4.043-.06-1.064-.049-1.791-.218-2.427-.465a4.902 4.902 0 01-1.772-1.153 4.902 4.902 0 01-1.153-1.772c-.247-.636-.416-1.363-.465-2.427-.047-1.024-.06-1.379-.06-3.808v-.63c0-2.43.013-2.784.06-3.808.049-1.064.218-1.791.465-2.427a4.902 4.902 0 011.153-1.772A4.902 4.902 0 015.45 2.525c.636-.247 1.363-.416 2.427-.465C8.901 2.013 9.256 2 11.685 2h.63zm-.081 1.802h-.468c-2.456 0-2.784.011-3.807.058-.975.045-1.504.207-1.857.344-.467.182-.8.398-1.15.748-.35.35-.566.683-.748 1.15-.137.353-.3.882-.344 1.857-.047 1.023-.058 1.351-.058 3.807v.468c0 2.456.011 2.784.058 3.807.045.975.207 1.504.344 1.857.182.466.399.8.748 1.15.35.35.683.566 1.15.748.353.137.882.3 1.857.344 1.054.048 1.37.058 4.041.058h.08c2.597 0 2.917-.01 3.96-.058.976-.045 1.505-.207 1.858-.344.466-.182.8-.398 1.15-.748.35-.35.566-.683.748-1.15.137-.353.3-.882.344-1.857.048-1.055.058-1.37.058-4.041v-.08c0-2.597-.01-2.917-.058-3.96-.045-.976-.207-1.505-.344-1.858a3.097 3.097 0 00-.748-1.15 3.098 3.098 0 00-1.15-.748c-.353-.137-.882-.3-1.857-.344-1.023-.047-1.351-.058-3.807-.058zM12 6.865a5.135 5.135 0 110 10.27 5.135 5.135 0 010-10.27zm0 1.802a3.333 3.333 0 100 6.666 3.333 3.333 0 000-6.666zm5.338-3.205a1.2 1.2 0 110 2.4 1.2 1.2 0 010-2.4z" clip-rule="evenodd"></path>
                </svg>
            </a>
            
            
            <a href="#" class="text-gray-400 hover:text-gray-300">
                <span class="sr-only">Twitter</span>
                <svg class="w-6 h-6" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
                    <path d="M8.29 20.251c7.547 0 11.675-6.253 11.675-11.675 0-.178 0-.355-.012-.53A8.348 8.348 0 0022 5.92a8.19 8.19 0 01-2.357.646 4.118 4.118 0 001.804-2.27 8.224 8.224 0 01-2.605.996 4.107 4.107 0 00-6.993 3.743 11.65 11.65 0 01-8.457-4.287 4.106 4.106 0 001.27 5.477A4.072 4.072 0 012.8 9.713v.052a4.105 4.105 0 003.292 4.022 4.095 4.095 0 01-1.853.07 4.108 4.108 0 003.834 2.85A8.233 8.233 0 012 18.407a11.616 11.616 0 006.29 1.84"></path>
                </svg>
            </a>
            
            
            <a href="#" class="text-gray-400 hover:text-gray-300">
                <span class="sr-only">GitHub</span>
                <svg class="w-6 h-6" fill="currentColor" viewBox="0 0 24 24" aria-hidden="true">
                    <path fill-rule="evenodd" d="M12 2C6.477 2 2 6.484 2 12.017c0 4.425 2.865 8.18 6.839 9.504.5.092.682-.217.682-.483 0-.237-.008-.868-.013-1.703-2.782.605-3.369-1.343-3.369-1.343-.454-1.158-1.11-1.466-1.11-1.466-.908-.62.069-.608.069-.608 1.003.07 1.531 1.032 1.531 1.032.892 1.53 2.341 1.088 2.91.832.092-.647.35-1.088.636-1.338-2.22-.253-4.555-1.113-4.555-4.951 0-1.093.39-1.988 1.029-2.688-.103-.253-.446-1.272.098-2.65 0 0 .84-.27 2.75 1.026A9.564 9.564 0 0112 6.844c.85.004 1.705.115 2.504.337 1.909-1.296 2.747-1.027 2.747-1.027.546 1.379.202 2.398.1 2.651.64.7 1.028 1.595 1.028 2.688 0 3.848-2.339 4.695-4.566 4.943.359.309.678.92.678 1.855 0 1.338-.012 2.419-.012 2.747 0 .268.18.58.688.482A10.019 10.019 0 0022 12.017C22 6.484 17.522 2 12 2z" clip-rule="evenodd"></path>
                </svg>
            </a>
            
        </div>
        <p class="mt-8 text-base text-center text-gray-400">© 2025
            TechOverflow. All rights
            reserved.</p>
        <p class="mt-2 text-base text-center text-gray-400">Tailbliss Theme for Hugo - made with ❤️ by <a href="https://nusserstudios.com/" class="hover:underline hover:text-primary-600"><span class="font-black uppercase">Nusser</span> <span class="font-light uppercase">Studios.</span></a>
        </p>
    </div>
</footer>


<script type="text/javascript" src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/kicad.js" defer="defer"></script>


<script type="text/javascript" src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/docsearch.js" defer="defer"></script>


<script type="text/javascript" src="How%20to%20interpret%20smartctl%20messages%20like%20%E2%80%98Error_%20UNC%20at%20LBA%E2%80%99_%20_%20TechOverflow_fichiers/algolia.js" defer="defer"></script>


<div id="nguard-popover-hover" style="display: block;"></div></body></html>