{"id":212,"date":"2017-08-28T15:38:16","date_gmt":"2017-08-28T15:38:16","guid":{"rendered":"https:\/\/d1m0.com\/?p=212"},"modified":"2017-08-29T15:30:02","modified_gmt":"2017-08-29T15:30:02","slug":"software-raidbasics-and-how-to","status":"publish","type":"post","link":"https:\/\/d1m0.com\/?p=212","title":{"rendered":"Software Raid,basics and how to."},"content":{"rendered":"

1. Create
\n1.1 Levels
\n2. Monitor
\n2.1 Follow
\n3. Build Manage
\n4. Grow
\n5. hints<\/p>\n

<\/p>\n

1. Create<\/p>\n

sudo mdadm –zero-superblock \/dev\/sdc
\nsudo mdadm –zero-superblock \/dev\/sdd
\nsudo mdadm –create –verbose \/dev\/md0 –level=0 –raid-devices=2 \/dev\/sda \/dev\/sdb
\ncat \/proc\/mdstat<\/p><\/blockquote>\n

Create and Mount the Filesystem<\/p>\n

sudo mkfs.ext4 -F \/dev\/md0
\nsudo mkdir -p \/mnt\/md0
\nsudo mount \/dev\/md0 \/mnt\/md0<\/p><\/blockquote>\n

Save the Array Layout<\/p>\n

sudo mdadm –detail –scan | sudo tee -a \/etc\/mdadm\/mdadm.conf
\nsudo update-initramfs -u
\necho ‘\/dev\/md0 \/mnt\/md0 ext4 defaults,nofail,discard 0 0’ | sudo tee -a \/etc\/fstab<\/p><\/blockquote>\n

1.1 Levels<\/p>\n

Level 4<\/p>\n

mdadm –create –verbose \/dev\/md0 –level=4 –raid-devices=4 \/dev\/sdb \/dev\/sdc \/dev\/sdd \/dev\/sde spare-devices=\/dev\/sdf<\/p><\/blockquote>\n

Level 5<\/p>\n

mdadm –create \/dev\/md0 –level=5 –raid-devices=4 \/dev\/sda1 \/dev\/sdb1 \/dev\/sdc1 \/dev\/sdd1
\nmdadm –assemble \/dev\/md0 \/dev\/sda1 \/dev\/sdb1 \/dev\/sdc1 \/dev\/sdd1<\/p><\/blockquote>\n

Level 1<\/p>\n

mdadm –create –verbose \/dev\/md0 –level=mirror –raid-devices=2 \/dev\/sdb1 \/dev\/sdc1
\nmdadm –assemble \/dev\/md0 \/dev\/sdb1 \/dev\/sdc1<\/p><\/blockquote>\n

Level 0<\/p>\n

mdadm –create –verbose \/dev\/md0 –level=stripe –raid-devices=2 \/dev\/sdb6 \/dev\/sdc5<\/p><\/blockquote>\n

If you have spare disks, you can add them to the end of the device specification like<\/p>\n

mdadm –create –verbose \/dev\/md0 –level=mirror –raid-devices=2 \/dev\/sdb1 \/dev\/sdc1 –spare-devices=1 \/dev\/sdd1<\/p><\/blockquote>\n

2.Monitoring mdadm, Follow<\/p>\n

cat \/proc\/mdstat
\nmdadm -D \/dev\/md0
\nmdadm –query \/dev\/md0
\nmdadm -E \/dev\/sdc1
\nmdadm –verbose –detail -scan<\/p><\/blockquote>\n

2.1Follow<\/p>\n

mdadm –monitor –mail=root –delay=300 \/dev\/md0<\/p><\/blockquote>\n

You can also specify -y option to let mdadm write log into syslog.<\/p>\n

chkconfig mdmonitor on
\nchkconfig –list mdmonitor
\nmdmonitor 0:off 1:off 2:on 3:on 4:on 5:on 6:off
\nBy default, it uses the following options
\nOPTIONS=”–monitor –scan -f –pid-file=$PIDFILE”<\/p><\/blockquote>\n

test it<\/p>\n

mdadm –monitor -t \/dev\/md1<\/p><\/blockquote>\n

 <\/p>\n

3.Build, Manage, adding, removing<\/p>\n

mdadm –stop \/dev\/md0
\nmdadm –remove \/dev\/md0<\/p><\/blockquote>\n

To start (assemble) a stopped array :<\/p>\n

mdadm –asemble \/dev\/md0
\nmdadm –add \/dev\/md0 \/dev\/sdd<\/p><\/blockquote>\n

removing a device<\/p>\n

We can fail a device (-f) from an array and then remove (-r) it:<\/p>\n

mdadm –manage \/dev\/md0 -f \/dev\/sdd
\nmdadm –manage \/dev\/md0 -r \/dev\/sdd<\/p><\/blockquote>\n

5.Hitns
\nlsblk -o NAME,SIZE,FSTYPE,TYPE,MOUNTPOINT<\/p>\n","protected":false},"excerpt":{"rendered":"

1. Create 1.1 Levels 2. Monitor 2.1 Follow 3. Build Manage 4. Grow 5. hints<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[],"class_list":["post-212","post","type-post","status-publish","format-standard","hentry","category-linux"],"_links":{"self":[{"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/posts\/212","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/d1m0.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=212"}],"version-history":[{"count":6,"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/posts\/212\/revisions"}],"predecessor-version":[{"id":218,"href":"https:\/\/d1m0.com\/index.php?rest_route=\/wp\/v2\/posts\/212\/revisions\/218"}],"wp:attachment":[{"href":"https:\/\/d1m0.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=212"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/d1m0.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=212"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/d1m0.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=212"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}