RAID configuration on a Scaleway Dedibox

RAID Overview

RAID is a data storage technology used for the purpose of data redundancy, performance improvement, or both by combining multiple physical hard drives into one or more logical drives.

The different RAID schemes are referenced as levels and are named by the word RAID itself, followed by a number (For example RAID 0, RAID 1 or RAID 5). Depending on the RAID level, data is distributed and stored across the disks in one or several ways. Each of the different raid levels addresses another use-case:

RAID 0

RAID 0 uses data striping, this increases the storage capacity of the virtual disk to the sum of all available disks in the RAID. The write and read performances of the machine are increased in RAID 0 die to concurrent read and write operations. There is zero fault tolerance in RAID 0, as the contents of each file are distributed among all disks in the set, the failure of any single disk in the RAID array causes the entire RAID 0 volume to break down.
The minimum number of disks in a RAID 0 set is two.

RAID 1

RAID 1 uses disk mirroring, this means data is written identically to any of the two disks in the set. File requests are broadcasted to any drive in the array and can be served by the drive that accesses the data at first, improving read performances. Write performance can be slower than using a single drive, as any write request has to be sent to all drives in the set, limiting the write performances to the speed of the slowest disk. A fault tolerance is provided using this RAID level, as data can be restored from the second disk in case one disk fails. The minimum number of disks available in a RAID 1 set is two and the number can be increased in odd pairs (For example: 2, 4, 6, …)

RAID 5

RAID 5 uses block-level data striping with distributed parity. This means parity information is distributed among all available drives, resulting in a fault tolerance where all drives but one need to be present to operate. In case a single drive fails, subsequent reads can be calculated from the distributed parity available on the other drives, so that no data is lost. This RAID level requires a minimum of three disks in the set and the total available space of the virtual disk is the sum of all drives minus one.

Requirements

Software RAID Configuration

A software RAID is a type of RAID implementation using capabilities of the operating system to construct and manage the RAID. It does not use a dedicated RAID controller but host system resources such as the CPU or RAM to provide RAID services using a software driver.

The RAID configuration of a software RAID can be done during the installation of a Scaleway Dedibox having at least two disk drives (HDD or SSD) and is available depending on the capabilities of the operating system.

1 . Log into the Scaleway Dedibox console

2 . Click on Server > Server list to display a list of available servers in the account.

3 . Select the server to install and click Manage

4 . On the server status overview page, click Install:

5 . The available operating systems are grouped by their different use cases. Choose the use case corresponding to your project and click the button:

6 . Choose the distribution and version to be installed on the server and click the Install button:

7 . Configure the disk partitioning:

You can select the Filesystem, RAID level and set the mount point as well as the partition size in MB.

If the server has two disks, the RAID levels RAID 0, RAID 1 and No RAID are proposed. If the server has more than two disks installed, also RAID 5 is proposed. Set the configuration towards your needs, if a software RAID is configured, make sure that the partitioning on all disks of the RAID is identical.

The following restrictions apply during partitioning:

  • The disks can have a maximum of 4 primary partitions.
  • Do not create a /var partition, is is likely that the installation will fail.
  • The / partition must be at least 2048MB large.

Once configured click VALIDATE to confirm the partition layout and to proceed to the next step.

8 . Set a user and eventually administrator password and select SSH keys that will be able to connect to the server. Click Next Step once all set.

9 . A configuration summary displays. Confirm the configuration by clicking DELETE ALL MY DISKS AND INSTALL THE SYSTEM!. This launches the automatic installation of the server.

Important: This will delete all data present on the disks. Make sure to have a backup of your data before launching the re-installation of a Scaleway Dedibox to avoid data loss!

Hardware RAID Configuration

A hardware RAID a type of RAID implementation where construction and management of the RAID is done on dedicated hardware, independently from the operating system.
The logical disks of the RAID array are managed by a physical controller, sitting on the PCI bus, which presents only the logical volumes to the operating system. The RAID controller manages the RAID using its own CPU and RAM, without delegating tasks to the main CPU of the machine.

To configure a hardware RAID on Scaleway Dedibox, two main options are available:

Raid Configuration From the Management Console

1 . Log into the Scaleway Dedibox console

2 . Click on Server > Server list to display a list of available servers in the account.

3 . Select the server to install and click Manage

4 . Click RAID configuration in the menu:

5 . Choose the RAID level for the server from the drop-down list and confirm by clicking ERASE ALL MY DATA AND PROCEED TO RAID LEVEL CHANGES.

Important: This will delete all data on the servers disks. Make sure to have a backup of your data before changing the RAID level of the machine.

6 . Once done, proceed with a reinstallation of the operating system from the console.

Raid Configuration Using the KVM-over-IP Device

Important: This method is recommended only for advanced users. The RAID configuration utility may differ depending on the hardware reference of your server. Be careful, modifications to the RAID directly using the configuration tool of the controller may harm your server.

1 . Log into the Scaleway Dedibox console

2 . Click on Server > Server list to display a list of available servers in the account.

3 . Select the server to configure and click KVM OVER IP, IDRAC or ILO depending on the hardware manufacturer of the chassis.

4 . Enter the IP address of your Internet connection to create a secure KVM-over-IP session and validate the form.

5 . Connect to the KVM over IP device and launch the virtual console.

6 . Reboot the machine and enter the RAID configuration tool during the boot process.

7 . Configure the hardware RAID towards your needs.

Discover New Bare Metal Cloud servers