RAID or less commonly known as Redundant Array of Independent Disks is a data storage virtualization combining several physical disks drives into a single unit for various reasons. These include performance optimization, data redundancy or both.
In this setup, data is distributed across the disk drives. Depending on the type of performance or redundancy desired, there are several types of levels named RAID 0, 1, 2 etc. In this short guide, we will be looking at three common levels.
RAID Levels Explained
RAID 0: First off we look at this level and as the name implies it brings zero to the table in terms of reliability. If you have two disks all this does is it increases your usage capacity to the combined total available in both disks. However, it strips the data across these drives. This gives you greater read and writes performance from the drives.
Performance is achieved because of concurrent writes of the files thereby doubling the performance.
The cons here is that if one of your drives goes south then you lose all the data on both drives, not just the bad one because the data was stripped across both drives. Therefore when you use this configuration you had better take plenty of backups.
So why would one want to ever use one of these? Well, to take advantage of the performance of running multiple SSDs would be reason enough to go for it.
RAID 1: On the other hand, if performance is not such an issue but reliability is, then RAID 1 is for an option. This configuration allows you to have the performance of half of your drives and the storage capacity of half of your drives as well. It, however, increases the reliability in that it saves the data redundantly on all the drives. If you lose one drive you still have access to all of your data.
This solution is ideal for those who maintain a premium on the data over performance.
RAID 10 – Nested (hybrid) RAID: This configuration combines the benefits of RAID 0 and RAID 1. With this set up you get half the performance of all the drives and half the storage capacity of all the drives. You need a minimum of four disks for this set up to work.
Ideally, you would perform a RAID 0 on the two initial disks and mirror (RAID 1) those to two other disks. This set up allows for you to lose a maximum of two disks and still get all your data back. In the end, you get your performance and reliability plus additional storage space out of this.
There are other levels not mentioned here as they are no longer used or are more appropriate for more professional setups therefore are beyond the scope of this guide. With that said, RAID 2 and RAID 3 are no longer in use in modern systems. These two Levels are like RAID 0 but strip at the bit level. RAID 4 is also not used but there is a propriety version in use. This one strips at block-level with dedicated parity.
RAID 5 is in use and requires a minimum of three drives to work and are susceptible to system failures. RAID 6 like RAID 5 does block-level striping and requires a minimum of four drives and can tolerate failure in two drives at most. There far many more configuration beyond these but that’s all we have for now on this topic.
With that said. Having RAID drives is no substitute for having a good old back up systems in place. Now you know.