How To Create RAID 10 Or 1+0 (Nested)
RAID 10 is a combine of RAID 0 and RAID 1 to form a RAID 10. To setup Raid 10, we need at least 4 number of disks. In our earlier articles, we’ve seen how to setup a RAID 0 and RAID 1 with minimum 2 number of disks.
About raid 10
Combining these two storage levels makes RAID 10 fast and resilient at the same time. If you need hardware-level protection for your data and faster storage performance, RAID 10 is a simple, relatively inexpensive fix. RAID 10 is secure because mirroring duplicates all your data. It’s fast because the data is striped across multiple disks; chunks of data can be read and written to different disks simultaneously.
To implement RAID 10, you need at least four physical hard drives. You also need a disk controller that supports RAID.
Gives better performance.
We will loose two of the disk capacity in RAID 10.
Reading and writing will be very good, because it will write and read to all those 4 disk at the same time.
It can be used for Database solutions, which needs a high I/O disk writes.
Requirements
In RAID 10, we need minimum of 4 disks, the first 2 disks for RAID 0 and other 2 Disks for RAID 1. Like I said before, RAID 10 is just a Combine of RAID 0 & 1. If we need to extended the RAID group, we must increase the disk by minimum 4 disks.
To create RAID 10 follow the nest steps:
Update the system and install “mdadm” package:
The mdadm is a small program, which will allow us to configure and manage RAID devices in Linux.
After the ‘mdadm‘ package installation, let’s list the three 20GB disks which we have added to our system using ‘fdisk‘ command.
Software RAID 6 or Striping with Double Distributed Parity in Linux systems or servers using four 20GB disks named /dev/sdb, /dev/sdc, /dev/sdd and /dev/sde.
Creating partition for RAID 10
. Now create a new partition on all 4 disks (/dev/sdb, /dev/sdc, /dev/sdd and /dev/sde) using the ‘fdisk’ tool.
# fdisk /dev/sdb # fdisk /dev/sdc # fdisk /dev/sdd # fdisk /dev/sde
Create /dev/sdb Partition
Let me show you how to partition one of the disk (/dev/sdb) using fdisk, this steps will be the same for all the other disks too.
# fdisk /dev/sdb
Please use the below steps for creating a new partition on /dev/sdb drive.
Press ‘n‘ for creating new partition.
Then choose ‘P‘ for Primary partition.
Then choose ‘1‘ to be the first partition.
Next press ‘p‘ to print the created partition.
Change the Type, If we need to know the every available types Press ‘L‘.
Here, we are selecting ‘fd‘ as my type is RAID.
Next press ‘p‘ to print the defined partition.
Then again use ‘p‘ to print the changes what we have made.
Use ‘w‘ to write the changes.
Creating RAID 10 md device
Now it’s time to create a ‘md’ (i.e. /dev/md0) device, using ‘mdadm’ raid management tool. Before, creating device, your system must have ‘mdadm’ tool installed, if not install it first.
# yum install mdadm [on RedHat systems] # apt-get install mdadm [on Debain systems]
Once ‘mdadm’ tool installed, you can now create a ‘md’ raid device using the following command.
# mdadm --create /dev/md0 --level=10 --raid-devices=4 /dev/sd[b-e]1
Next verify the newly created raid device using the ‘cat’ command.
# cat /proc/mdstat
Next, examine all the 4 drives using the below command. The output of the below command will be long as it displays the information of all 4 disks.
# mdadm --examine /dev/sd[b-e]1
Next, check the details of Raid Array with the help of following command.
# mdadm --detail /dev/md0
Creating Filesystem
Create a file system using ext4 for ‘md0’ and mount it under ‘/mnt/raid10‘. Here, I’ve used ext4, but you can use any filesystem type if you want.
# mkfs.ext4 /dev/md0
After creating filesystem, mount the created file-system under ‘/mnt/raid10‘ and list the contents of the mount point using ‘ls -l’ command.
# mkdir /mnt/raid10 # mount /dev/md0 /mnt/raid10/ # ls -l /mnt/raid10/
Next, add some files under mount point and append some text in any one of the file and check the content.
# touch /mnt/raid10/raid10_files.txt # ls -l /mnt/raid10/ # echo "raid 10 setup with 4 disks" > /mnt/raid10/raid10_files.txt # cat /mnt/raid10/raid10_files.txt
For automounting, open the ‘/etc/fstab‘ file and append the below entry in fstab, may be mount point will differ according to your environment. Save and quit using wq!.
# vim /etc/fstab /dev/md0 /mnt/raid10 ext4 defaults 0 0
Next, verify the ‘/etc/fstab‘ file for any errors before restarting the system using ‘mount -a‘ command.
# mount -av
Save RAID Configuration
By default RAID don’t have a config file, so we need to save it manually after making all the above steps, to preserve these settings during system boot.
# mdadm --detail --scan --verbose >> /etc/mdadm.conf
