{"id":3244,"date":"2020-11-05T23:46:30","date_gmt":"2020-11-05T18:16:30","guid":{"rendered":"https:\/\/www.24x7serversupport.com\/blog\/?p=3244"},"modified":"2023-01-23T17:45:45","modified_gmt":"2023-01-23T12:15:45","slug":"bad-magic-number-in-superblock","status":"publish","type":"post","link":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/","title":{"rendered":"Bad Magic Number In Superblock"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">Bad Magic Number In Superblock<\/h2>\n\n\n\n<p>The&nbsp;Server will go down due to issues in disks attached. Sometimes fsck in disks ends up in an error \u201cBad magic number in Superblock while trying to open \/dev\/sdb\u201d.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>What do you mean by superblock?<\/strong><\/h3>\n\n\n\n<p>The superblock means a file system metadata (data of a data) that describes the size, type, and status of the file system and information regarding other metadata structures.&nbsp;It is very significant to the file system. Hence, for each file system, the superblock is retained in multiple redundant copies.&nbsp;If the superblock of a partition is corrupt, we are not able to mount the file system of partition by operating system.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>What is a magic number?<\/strong><\/h3>\n\n\n\n<p>Magic numbers are the first few bytes of a file which are unique to a particular file type and they are also called file signature. Magic numbers\/File signatures are t not visible to the user.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>How can see information about superblock and magic number?<\/strong><\/h3>\n\n\n\n<p>We can view superblock header of an existing file system using dumpe2fs<\/p>\n\n\n\n<p><code># dumpe2fs -h \/dev\/sdb<br>[root@sss ~]# dumpe2fs -h \/dev\/sdb<br>dumpe2fs 1.42.9 (28-Dec-2013)<br>Filesystem volume name:&lt;none&gt;<br>Last mounted on:&lt;not available&gt;<br>Filesystem UUID:d6cd4d1a-c69f-4e81-8e7a-ed6cf0be68db<br>Filesystem magic number:0xEF53<br>Filesystem revision #:1 (dynamic)<br>Filesystem features:has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg sparse_super large_file huge_file uninit_bg dir_nlink extra_isize<br>Filesystem flags:signed_directory_hash<br>Default mount options:user_xattr acl<br>Filesystem state:clean<br>Errors behavior:Continue<br>Filesystem OS type:Linux<br>Inode count:720896<br>Block count:2883584<br>Reserved block count:144179<br>Free blocks:2795308<br>Free inodes:720885<br>First block:0<br>Block size:4096<br>Fragment size:4096<br>Group descriptor size:64<br>Reserved GDT blocks:1024<br>Blocks per group:32768<br>Fragments per group:32768<br>Inodes per group:8192<br>Inode blocks per group:512<br>Flex block group size:16<br>Filesystem created:Wed Dec 20 02:33:43 2017<br>Last mount time:Wed Dec 20 02:34:40 2017<br>Last write time:Wed Dec 20 02:34:40 2017<br>Mount count:1<br>Maximum mount count:-1<br>Last checked:Wed Dec 20 02:33:43 2017<br>Check interval:0<br>Lifetime writes:132 MB<br>Reserved blocks uid:0 (user root)<br>Reserved blocks gid:0 (group root)<br>First inode:11<br>Inode size:256<br>Required extra isize:28<br>Desired extra isize:28<br>Journal inode:8<br>Default directory hash:half_md4<br>Directory Hash Seed: c577c1b0-aaa9-4d27-b5e6-54bd5b9540d1<br>Journal backup: inode blocks<br>Journal features: journal_64bit<br>Journal size: 128M<br>Journal length: 32768<br>Journal sequence: 0x00000002<br>Journal start: 1<\/code><\/p>\n\n\n\n<p>In order to view the magic number of a file, we need to install xxd command Note that plain text files do not have the magic number.<\/p>\n\n\n\n<p><code>#yum install vim-common -y<\/code><\/p>\n\n\n\n<p><code>#xxd img-1500x1032-data.jpg |head<br>[root@sss ~]# xxd img-1500x1032-data.jpg |head<br>0000000: ffd8 ffe0 0010 4a46 4946 0001 0101 0048 ......JFIF.....H<br>0000010: 0048 0000 ffe1 17f2 4578 6966 0000 4d4d .H......Exif..MM<br>0000020: 002a 0000 0007 0008 0112 0003 0000 0001 .*..............<br>0000030: 0001 0000 011a 0005 0000 0001 0000 0063 ...............b<br>0000040: 011b 0005 0000 0001 0000 006a 0148 0003 ...........j.(..<br>0000050: 0000 0001 0002 0000 0121 0002 0000 001e .........1......<br>0000060: 0000 0072 0142 0002 0000 0014 0000 008f ...r.2..........<br>0000070: 8769 0004 0000 0001 0000 00a3 0000 00cd .i..............<br>0000080: 000a fc80 0000 2710 000a fc80 0000 2710 ......'.......'.<br>0000090: 4164 6f62 6520 5068 6f74 6f73 686f 7020 Adobe Photoshop<\/code><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><strong>What is \u201cBad magic number in superblock\u201d?<\/strong><\/h3>\n\n\n\n<p>The magic number of the file system is stored in the Superblock. This magic number is used by OS to determine which is the file system related to disk \/dev\/sdb<\/p>\n\n\n\n<p><code>[root@sss ~]# dumpe2fs -h \/dev\/sdb |grep -i magic<br>dumpe2fs 1.42.9 (28-Dec-2013)<br>Filesystem magic number: 0xEF53<\/code><\/p>\n\n\n\n<p>A&nbsp;Bad magic number in superblock error is a clear indication that the operating system is not able to determine file system type of \/dev\/sdb using superblock data.<\/p>\n\n\n\n<p>Solution<br>1) Find the&nbsp;backup of superblocks using dumpe2fs or mke2fs<\/p>\n\n\n\n<p>dumpe2fs will work on mounted or unmounted disk but mke2fs require disk unmounted.<\/p>\n\n\n\n<p><code>#dumpe2fs -h \/dev\/sdb<\/code><\/p>\n\n\n\n<p><code>[root@sss ~]# dumpe2fs \/dev\/sdb |grep -i superblock<br>dumpe2fs 1.42.9 (28-Dec-2013)<br>Primary superblock at 0, Group descriptors at 1-2<br>Backup superblock at 32768, Group descriptors at 32769-32770<br>Backup superblock at 98304, Group descriptors at 98305-98306<br>Backup superblock at 163840, Group descriptors at 163841-163842<br>Backup superblock at 229376, Group descriptors at 229377-229378<br>Backup superblock at 294912, Group descriptors at 294913-294914<br>Backup superblock at 819200, Group descriptors at 819201-819202<br>Backup superblock at 884736, Group descriptors at 884737-884738<br>Backup superblock at 1605632, Group descriptors at 1605633-1605634<br>Backup superblock at 2654208, Group descriptors at 2654209-2654210<\/code><\/p>\n\n\n\n<p><code>[root@sss ~]# #mke2fs -n \/dev\/sdb<br>\/dev\/sdb is entire device, not just one partition!<br>Proceed anyway? (y,n) y<br>Filesystem label=<br>OS type: Linux<br>Block size=4096 (log=2)<br>Fragment size=4096 (log=2)<br>Stride=0 blocks, Stripe width=0 blocks<br>720896 inodes, 2883584 blocks<br>144179 blocks (5.00%) reserved for the superuser<br>First data block=0<br>Maximum filesystem blocks=2952790016<br>88 block groups<br>32768 blocks per group, 32768 fragments per group<br>8192 inodes per group<br>Superblock backups stored on blocks:<br>32769, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208<\/code><\/p>\n\n\n\n<p>2) Replace the superblock using the&nbsp;backup superblock<\/p>\n\n\n\n<p><code>#fsck -b 32768 \/dev\/sdb<\/code><br>or<br><code>#mount sb=32768 \/dev\/sdb \/mountpoint<\/code><br>or<br><code>#e2fsck -b 32768 \/dev\/sdb<\/code><\/p>\n\n\n\n<p>If we are getting the same error with superblock located on 32768, repeat the step with another superblock location.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Bad Magic Number In Superblock The&nbsp;Server will go down due to issues in disks attached. Sometimes fsck in disks ends up in an error \u201cBad magic number in Superblock while trying to open \/dev\/sdb\u201d. What do you mean by superblock? The superblock means a file system metadata (data of a data) that describes the size, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3511,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[30,237,38,33,238,273,321,243,34],"tags":[],"class_list":["post-3244","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-centos","category-centoswebpanel","category-cloudlinux","category-cpanel","category-cwp","category-directadmin","category-freebsd","category-kali-linux","category-linux"],"jetpack_publicize_connections":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Bad Magic Number In Superblock | 24x7serversupport Blog<\/title>\n<meta name=\"description\" content=\"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Bad Magic Number In Superblock | 24x7serversupport Blog\" \/>\n<meta property=\"og:description\" content=\"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/\" \/>\n<meta property=\"og:site_name\" content=\"24x7serversupport Blog\" \/>\n<meta property=\"article:published_time\" content=\"2020-11-05T18:16:30+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-01-23T12:15:45+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1280\" \/>\n\t<meta property=\"og:image:height\" content=\"720\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"24x7support\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@24x7serversuppo\" \/>\n<meta name=\"twitter:site\" content=\"@24x7serversuppo\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"24x7support\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"4 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/\",\"url\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/\",\"name\":\"Bad Magic Number In Superblock | 24x7serversupport Blog\",\"isPartOf\":{\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage\"},\"image\":{\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage\"},\"thumbnailUrl\":\"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1\",\"datePublished\":\"2020-11-05T18:16:30+00:00\",\"dateModified\":\"2023-01-23T12:15:45+00:00\",\"author\":{\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/#\/schema\/person\/decfb5fad6bde6ac6822d4e965c6d401\"},\"description\":\"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,\",\"breadcrumb\":{\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage\",\"url\":\"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1\",\"contentUrl\":\"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1\",\"width\":1280,\"height\":720,\"caption\":\"Bad Magic Number In Superblock\"},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.24x7serversupport.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Bad Magic Number In Superblock\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/#website\",\"url\":\"https:\/\/www.24x7serversupport.com\/blog\/\",\"name\":\"24x7serversupport Blog\",\"description\":\"Linux | CPanel | WHM | webhosting| Plesk | DirectAdmin | CentOs | Debian | Ubuntu Blog\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/www.24x7serversupport.com\/blog\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"en-US\"},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.24x7serversupport.com\/blog\/#\/schema\/person\/decfb5fad6bde6ac6822d4e965c6d401\",\"name\":\"24x7support\",\"url\":\"https:\/\/www.24x7serversupport.com\/blog\/author\/24x7support\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Bad Magic Number In Superblock | 24x7serversupport Blog","description":"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/","og_locale":"en_US","og_type":"article","og_title":"Bad Magic Number In Superblock | 24x7serversupport Blog","og_description":"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,","og_url":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/","og_site_name":"24x7serversupport Blog","article_published_time":"2020-11-05T18:16:30+00:00","article_modified_time":"2023-01-23T12:15:45+00:00","og_image":[{"width":1280,"height":720,"url":"https:\/\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg","type":"image\/jpeg"}],"author":"24x7support","twitter_card":"summary_large_image","twitter_creator":"@24x7serversuppo","twitter_site":"@24x7serversuppo","twitter_misc":{"Written by":"24x7support","Est. reading time":"4 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/","url":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/","name":"Bad Magic Number In Superblock | 24x7serversupport Blog","isPartOf":{"@id":"https:\/\/www.24x7serversupport.com\/blog\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage"},"image":{"@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage"},"thumbnailUrl":"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1","datePublished":"2020-11-05T18:16:30+00:00","dateModified":"2023-01-23T12:15:45+00:00","author":{"@id":"https:\/\/www.24x7serversupport.com\/blog\/#\/schema\/person\/decfb5fad6bde6ac6822d4e965c6d401"},"description":"Bad Magic Number In Superblock, Bad Magic Number In Superblock linux, Bad Magic Number In Superblock cpanel servers, debian, ubuntu,","breadcrumb":{"@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#primaryimage","url":"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1","contentUrl":"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1","width":1280,"height":720,"caption":"Bad Magic Number In Superblock"},{"@type":"BreadcrumbList","@id":"https:\/\/www.24x7serversupport.com\/blog\/bad-magic-number-in-superblock\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.24x7serversupport.com\/blog\/"},{"@type":"ListItem","position":2,"name":"Bad Magic Number In Superblock"}]},{"@type":"WebSite","@id":"https:\/\/www.24x7serversupport.com\/blog\/#website","url":"https:\/\/www.24x7serversupport.com\/blog\/","name":"24x7serversupport Blog","description":"Linux | CPanel | WHM | webhosting| Plesk | DirectAdmin | CentOs | Debian | Ubuntu Blog","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.24x7serversupport.com\/blog\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"en-US"},{"@type":"Person","@id":"https:\/\/www.24x7serversupport.com\/blog\/#\/schema\/person\/decfb5fad6bde6ac6822d4e965c6d401","name":"24x7support","url":"https:\/\/www.24x7serversupport.com\/blog\/author\/24x7support\/"}]}},"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.24x7serversupport.com\/blog\/wp-content\/uploads\/2020\/11\/bad-magic.jpg?fit=1280%2C720&ssl=1","jetpack_sharing_enabled":true,"jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/posts\/3244","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/comments?post=3244"}],"version-history":[{"count":1,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/posts\/3244\/revisions"}],"predecessor-version":[{"id":3245,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/posts\/3244\/revisions\/3245"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/media\/3511"}],"wp:attachment":[{"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/media?parent=3244"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/categories?post=3244"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.24x7serversupport.com\/blog\/wp-json\/wp\/v2\/tags?post=3244"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}