How to create Raid 01 over loop devices
hii guys today we will learn how to create raid 01 on loop devises . if you want to know what is loop devises so click how to create loop in redhat linux . so here we will start loop over raid
at fast we will make two loop device a.txt, b.txt
[root@localhost ~]# touch a.txt
[root@localhost ~]# touch b.txt
[root@localhost ~]# touch c.txt
[root@localhost ~]# touch d.txt
[root@localhost ~]# touch e.txt
[root@localhost ~]# touch f.txt
[root@localhost ~]# touch g.txt
then we will provide txt file size blow this commands
[root@localhost ~]# dd if=/dev/sda of=a.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=b.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=c.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=d.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=e.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=f.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=g.txt bs=2M count=100
[root@localhost ~]# dd if=/dev/sda of=h.txt bs=2M count=100
here our every file size is 200MB now we convert in loop devices blow commands
[root@localhost ~]# losetup /dev/loop0 a.txt
[root@localhost ~]# losetup /dev/loop1 b.txt
[root@localhost ~]# losetup /dev/loop2 c.txt
[root@localhost ~]# losetup /dev/loop3 d.txt
[root@localhost ~]# losetup /dev/loop4 e.txt
[root@localhost ~]# losetup /dev/loop5 f.txt
[root@localhost ~]# losetup /dev/loop6 g.txt
[root@localhost ~]# losetup /dev/loop7 h.txt
now we can look over loop devices through this commands [root@localhost ~]# losetup -a
[root@localhost ~]# losetup -a
/dev/loop0: [0801]:5197237 (a.txt)
/dev/loop1: [0801]:5197240 (b.txt)
/dev/loop2: [0801]:5197247 (c.txt)
/dev/loop3: [0801]:5197242 (d.txt)
/dev/loop4: [0801]:5197243 (e.txt)
/dev/loop5: [0801]:5197244 (f.txt)
/dev/loop6: [0801]:5197245 (g.txt)
/dev/loop7: [0801]:5197246 (h.txt)
now here we will configure raid 01 . before we create raid 0 .
[root@localhost ~]# mdadm –create /dev/md1 –level=0 –raid-device=2 /dev/loop0 /dev/loop1
mdadm: /dev/loop0 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:53:32 2017
mdadm: /dev/loop1 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:53:32 2017
Continue creating array? yes
mdadm: array /dev/md1 started.
[root@localhost ~]# mdadm –create /dev/md2 –level=0 –raid-device=2 /dev/loop2 /dev/loop3
mdadm: /dev/loop2 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop2 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:54:01 2017
mdadm: /dev/loop3 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop3 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:54:01 2017
Continue creating array? yes
mdadm: array /dev/md2 started.
here we have two md group md1 md2. and we used total 4 loop devises in both md group
then we will have four free loop devises so we create another group md3 and md 4
[root@localhost ~]# mdadm –create /dev/md3 –level=0 –raid-device=2 /dev/loop4 /dev/loop5
mdadm: /dev/loop4 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop4 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:54:55 2017
mdadm: /dev/loop5 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop5 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:54:55 2017
Continue creating array? yes
mdadm: array /dev/md3 started.
[root@localhost ~]# mdadm –create /dev/md4 –level=0 –raid-device=2 /dev/loop6 /dev/loop7
mdadm: /dev/loop6 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop6 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:55:39 2017
mdadm: /dev/loop7 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/loop7 appears to be part of a raid array:
level=raid1 devices=2 ctime=Mon Jan 9 06:55:39 2017
Continue creating array? yes
mdadm: array /dev/md4 started.
now we have md3 and md4 .then we will add md1 and md2.
[root@localhost ~]# mdadm –create /dev/md5 –level=0 –raid-device=2 /dev/md1 /dev/md2
mdadm: /dev/md1 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:08 2017
mdadm: /dev/md2 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/md2 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:08 2017
Continue creating array? yes
mdadm: array /dev/md5 started.
like same we will add md3 and md4
[root@localhost ~]# mdadm –create /dev/md6 –level=0 –raid-device=2 /dev/md3 /dev/md4
mdadm: /dev/md3 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/md3 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:53 2017
mdadm: /dev/md4 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/md4 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:53 2017
Continue creating array? yes
mdadm: array /dev/md6 started.
now we have new md group md5 and md6 . Here we will create raid 1 over md5 and md 6 then we found we create raid 01
[root@localhost ~]# mdadm –create /dev/md11 –level=1 –raid-device=2 /dev/md5 /dev/md6
mdadm: /dev/md5 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:08 2017
mdadm: /dev/md6 appears to contain an ext2fs file system
size=204800K mtime=Thu Jan 1 05:30:00 1970
mdadm: /dev/md6 appears to be part of a raid array:
level=raid0 devices=2 ctime=Mon Jan 9 06:58:53 2017
Continue creating array? yes
mdadm: array /dev/md11 started.
we can look raid 01 through this commands # cat /proc/mdstat
[root@localhost ~]# cat /proc/mdstat
Personalities : [raid0] [raid1]
md11 : active raid1 md6[1] md5[0]
818752 blocks [2/2] [UU]
md6 : active raid0 md4[1] md3[0]
818816 blocks 64k chunks
md5 : active raid0 md2[1] md1[0]
818816 blocks 64k chunks
md4 : active raid0 loop7[1] loop6[0]
409472 blocks 64k chunks
md3 : active raid0 loop5[1] loop4[0]
409472 blocks 64k chunks
md2 : active raid0 loop3[1] loop2[0]
409472 blocks 64k chunks
md1 : active raid0 loop1[1] loop0[0]
409472 blocks 64k chunks
unused devices:
next i will show you how can we permanent mount our raid 01 /(md11)
so before we format our md11 like this
[root@localhost ~]# mkfs.ext3 /dev/md11
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
102368 inodes, 204688 blocks
10234 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=209715200
7 block groups
32768 blocks per group, 32768 fragments per group
14624 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840
Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 38 mounts or
180 days, whichever comes first. Use tune2fs -c or -i to override.
here we will create data1 folder for md11 mounting
[root@localhost ~]# mkdir data1
[root@localhost ~]# mount /dev/md11 data1
now we do permanent mounting just go to #vim /etc/fstab
[root@localhost ~]# vim /etc/fstab
we will add { /root/data1 /dev/md11 ext3 defaults 0 0 }
LABEL=/ / ext3 defaults 1 1
tmpfs /dev/shm tmpfs defaults 0 0
devpts /dev/pts devpts gid=5,mode=620 0 0
sysfs /sys sysfs defaults 0 0
proc /proc proc defaults 0 0
LABEL=SWAP-sda2 swap swap defaults 0 0
/root/data1 /dev/md11 ext3 defaults 0 0
~
now your raid 01 is complet
THANK YOU
BY VISHNU SHARMA
