RAID


If you have complex redundancy or performance requirements, RAID can be a helpful solution.

Here you can find an updated list of the current RAID methods that the Maxihost platform supports, as well as a brief explanation of how RAID works.

Availability

 RAID Level RAID 0 RAID 1
Disks required 2+ 2+
Operating Systems supported
  • Ubuntu 16.04 LTS or newer
  • CentOS 7.4 or newer
  • Ubuntu 16.04 LTS or newer
  • CentOS 7.4 or newer
RAID Type Software Software
What it does Combines two or more disks by striping data across them. Read more. Mirrors data between two or more disks. Read more.

RAID levels explained

The RAID level is what determines the relationship of the disks. There are numerous RAID levels but here we will explain only the ones supported by Maxihost.

RAID 0

RAID 0 combines two or more disks by striping data across them, which means that chunks of data are written to each disk in the array alternately. This gives you a great performance improvement as the data is distributed between disks and each one can be utilized for both reads and writes.

This approach offers great performance as you get the performance of a single disk multiplied by the number of disks in the array and also get the combined capacity of all drives, but there is one important drawback that needs to be considered.

As data is being split up and divided between the disks in the array if one of the disks fails the entire array and all data is lost because the failure of a disk will remove the chunks that were written to it from the array, leaving the other disks with incomplete (as in corrupted) data. RAID 0 arrays cannot be rebuilt as there will be no knowledge by the other devices of the data that needs to be reconstructed.

If you decide to run a RAID 0 array, backups are extremely important, as your entire data set depends equally on the reliability of each of the disks in the array.

RAID 1

RAID 1 is a configuration that mirrors data between two or more disks. Everything written to the array is placed on each of the devices in the group, so each disk has a complete set of the available data.

This means that you have redundancy in case of device failure. In a RAID 1 array, data is accessible as long as a single disk in the array is functioning properly. The array can be rebuilt by replacing failed drives, at which point the remaining disks will be used to copy the data back to the new device.

In RAID 1 it's especially important that all disks in the array are performing well, as the performance of write operations will be that of the slowest device in the array. This happens because the whole piece of data must be written to each of the disks in the array.

It's also important to note that, as all of the data lives in each disk, the total capacity of the array will be that of the smallest disk. Adding new disks increases the number of redundant copies of the data, but doesn't increase the amount of available capacity.

For read operations, the theoretical performance is the same as with RAID 0 where you multiply the read speed of a single disk by the number of disks.

 


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