{"id":3132,"date":"2020-05-17T00:00:00","date_gmt":"2020-05-16T18:30:00","guid":{"rendered":"https:\/\/www.24x7serversupport.com\/blog\/?p=3132"},"modified":"2023-01-28T12:32:23","modified_gmt":"2023-01-28T07:02:23","slug":"linux-raid-with-mdadm-cheat-sheet","status":"publish","type":"post","link":"https:\/\/www.24x7serversupport.com\/blog\/linux-raid-with-mdadm-cheat-sheet\/","title":{"rendered":"Linux RAID with mdadm Cheat Sheet"},"content":{"rendered":"\n

RAID Levels<\/h3>\n\n\n\n
RAID 0<\/td>Stri\u00adpes<\/strong> data evenly across two or more disks.<\/td><\/tr>
RAID 1<\/td>Mirr\u00adors<\/strong> data on two or more disks.<\/td><\/tr>
RAID 2<\/td>Rarely used, Bit-level striping with Hamming code for error correc\u00adtion.<\/td><\/tr>
RAID 3<\/td>Rarely used, byte-level striping with a dedicated parity.<\/td><\/tr>
RAID 4<\/td>Block-\u00adlevel striping with dedi\u00adcated parity<\/strong>.<\/td><\/tr>
RAID 5<\/td>Block-\u00adlevel striping with dist\u00adributed parity<\/strong>.<\/td><\/tr>
RAID 6<\/td>Block-\u00adlevel striping with double distri\u00adbuted parity<\/strong>.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Nested RAID Levels<\/h3>\n\n\n\n
Number<\/strong><\/td>Desc\u00adrip\u00adtion<\/strong><\/td>Efficiency<\/strong><\/td><\/tr>
RAID 01<\/td>Block-\u00adlevel striping, and mirroring without parity<\/td>1\/stripes<\/td><\/tr>
RAID 10<\/td>Mirroring without parity, and block-\u00adlevel striping<\/td>stripes\/n<\/td><\/tr>
RAID 50<\/td>Block-\u00adlevel striping with distri\u00adbuted parity, and block-\u00adlevel striping<\/td>(1-str\u00adipes)\/n<\/td><\/tr>
RAID 60<\/td>Block-\u00adlevel striping with double distri\u00adbuted parity, and block-\u00adlevel striping<\/td>(1-2*s\u00adtri\u00adpes)\/n<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Formatting Disks for Use with mdadm<\/h3>\n\n\n\n
DISC\u00adLAIMER: PROCEED WITH CAUTION.<\/strong><\/td><\/tr>
MAKE SURE YOU KNOW WHAT DISK YOU ARE OPERATING ON. IT IS VERY EASY TO DO IRREVO\u00adCABLE DAMAGE TO YOUR SYSTEM IF YOU DON’T.<\/td><\/tr>
0. Figure out disk location in the file system:<\/strong><\/td><\/tr>
lsblk -o name,s\u00adize\u00ad,fs\u00adtyp\u00ade,t\u00adype\u00ad,mo\u00adunt\u00adpoint<\/code><\/td><\/tr>
1. Formatting with fdisk<\/strong><\/td><\/tr>
sudo fdisk \/dev\/sdx<\/code><\/td><\/tr>
2. Navigatng fdisk: just press the following keys when promted to create new linux RAID type primary partition<\/strong><\/td><\/tr>
n<\/code>, p<\/code>, 1<\/code>, Enter<\/code>, Enter<\/code>, t<\/code>, fd<\/code>, w<\/code><\/td><\/tr>
3. Repeat steps 1 and 2 for each disk that will be included in new array<\/strong><\/td><\/tr>
sudo fdisk \/dev\/sdy<\/code><\/td><\/tr>
n<\/code>, p<\/code>, 1<\/code>, Enter<\/code>, Enter<\/code>, t<\/code>, fd<\/code>, w<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Creating RAID arrays<\/h3>\n\n\n\n
Create a mirrored array<\/strong><\/td><\/tr>
mdadm –create \/dev\/md0 –level=1 \/dev\/sdx1 \/dev\/sdy1<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Assembling RAID arrays<\/h3>\n\n\n\n
Assemble an existing array<\/strong><\/td><\/tr>
mdadm --assemble \/dev\/md0 \/dev\/sdx1 \/dev\/sdy1<\/code><\/td><\/tr>
mdadm --scan --assemble --uuid=<UUID><\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Resetting Existing RAID Devices<\/h3>\n\n\n\n
Find the active arrays<\/strong><\/td><\/tr>
cat \/proc\/\u00admdstat<\/code><\/td><\/tr>
Unmount the array<\/strong><\/td><\/tr>
sudo umount \/dev\/md0<\/code><\/td><\/tr>
Stop and remove the array<\/strong><\/td><\/tr>
mdadm --stop \/dev\/md0<\/code><\/td><\/tr>
mdadm --remove \/dev\/md0<\/code><\/td><\/tr>
Find the devices used to build the array<\/strong><\/td><\/tr>
lsblk -o name,f\u00adsty\u00adpe,\u00admou\u00adntp\u00adoint<\/code><\/td><\/tr>
Zero out the respective superb\u00adlocks<\/strong><\/td><\/tr>
sudo mdadm --zero\u00ad-su\u00adper\u00adblock \/dev\/sdx<\/code><\/td><\/tr>
sudo mdadm --zero\u00ad-su\u00adper\u00adblock \/dev\/sdy<\/code><\/td><\/tr>
Remove persistent references to the array<\/strong><\/td><\/tr>
sudo nano \/etc\/f\u00adstab<\/code><\/td><\/tr>
Comment out or remove the reference to the array.<\/td><\/tr>
# \/dev\/md0 \/mnt\/md0 ext4 defaults,nofail,discard 0 0<\/code><\/td><\/tr>
In \/etc\/\u00admda\u00addm\/\u00admda\u00addm.c\u00adonf<\/code> comment out or remove the array reference<\/td><\/tr>
sudo nano \/etc\/m\u00addad\u00adm\/m\u00addad\u00adm.conf<\/code><\/td><\/tr>
Comment out the reference<\/td><\/tr>
# ARRAY \/dev\/md0 metada\u00adta=1.2 name=m\u00addad\u00admwr\u00adite:0 UUID=xxxx<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

RAID Levels RAID 0 Stri\u00adpes data evenly across two or more disks. RAID 1 Mirr\u00adors data on two or more disks. RAID 2 Rarely used, Bit-level striping with Hamming code for error correc\u00adtion. RAID 3 Rarely used, byte-level striping with a dedicated parity. RAID 4 Block-\u00adlevel striping with dedi\u00adcated parity. RAID 5 Block-\u00adlevel striping with […]<\/p>\n","protected":false},"author":1,"featured_media":3599,"comment_status":"closed","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":[30,38,238],"tags":[257,319,318,76,320],"class_list":["post-3132","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-centos","category-cloudlinux","category-cwp","tag-cheatsheet","tag-linuxcheatsheet","tag-madam","tag-raid","tag-raidcheatsheet"],"jetpack_publicize_connections":[],"yoast_head":"\nLinux RAID with mdadm Cheat Sheet | 24x7serversupport Blog<\/title>\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\/linux-raid-with-mdadm-cheat-sheet\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Linux RAID with mdadm Cheat Sheet | 24x7serversupport Blog\" \/>\n<meta property=\"og:description\" content=\"RAID Levels RAID 0 Stri\u00adpes data evenly across two or more disks. RAID 1 Mirr\u00adors data on two or more disks. RAID 2 Rarely used, Bit-level striping with Hamming code for error correc\u00adtion. RAID 3 Rarely used, byte-level striping with a dedicated parity. RAID 4 Block-\u00adlevel striping with dedi\u00adcated parity. 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