There comes a big concern of speed and reliability in selection of data storage disks, mainly in hard disk drives. To overcome and resolve such kind of issues, a technology named RAID was introduced. Let’s find out how this technology works with its different standards from RAID 0 to RAID 10. How RAID helps increasing speed and reliability of existing drives.
First Things First
Full Form of RAIDRedundant Array of Inexpensive Disks
Redundant Array of Independent Disks
As the name suggests, different physical independent disks are combined together on software or hardware level for the purpose of data redundancy and performance improvement. RAID is a data virtualization technology.
RAID can be implemented in very different ways using different levels like RAID 0, RAID 1, RAID 10, RAID 5 and so on. These works in different ways to give you a specific advantage, or more. Let’s have a quick look at different RAID levels below.
- Double the Read/Write data transfer speeds
- Reduces the reliability
- Overall capacity is doubled
RAID 0 Standard makes use of data striping. A part of data is stored on first disk whereas another part of same data is stored in another disk. The doubling of data transfer speed is possible because of two disk can work at same data at same instance of time.
As a result, some part of data is stored in disk 0 and another part of data is stored in disk 1, if any of the disk undergoes any hardware failure, complete data is corrupted. That’s why reliability is worsen by RAID 0.
If we use two disks of 1TB each, the resultant data we can store in entire setup is equivalent to 2TB. We can hence use the full storage capacity of both the disks in RAID 0 setup.
- Doubles the reliability of overall setup of disks
- Write speeds are not improved at all
- Read speeds undergoes good improvement
- Overall storage capacity is halved
RAID 1 setup makes use of data mirroring. i.e. same data is written into both the disks. In case of a single disk hardware failure, exact same copy of the data can be obtained from another disk. Read speeds are improved as the data can now be readed from both of the disks.
Written of the exact same data takes place on both of the disks and hence we can not experience any improvement in terms of write speed. Also, if we use two disks of 1TB each, we can store only 1TB of data in RAID 1 setup as the another disk is supposed to have a copy of data in the first disk.
Hybrid RAID or Nested RAID
Before going further in more advanced RAID 5 setup, let’s understand the very simple RAID 10 standard. As the name suggests it the combination of RAID 1 and RAID 0. The mirroring from RAID 1 and striping of data from RAID 0 are combined in RAID 10 standard.
- Doubles the read and write speeds
- Doubles the Reliability
- We need to have at least 4 disks for RAID 10 setup
- Overall storage capacity is halved
In the RAID 10 setup, two RAID 1 arrays are joined using RAID 0 such that both striping and mirroring of data takes place. Incoming data is first striped into two RAID 1 arrays and then its mirrored in both the drives.
The overall storage capacity that can really be used to store data is half of total capacity of disks. If we use four disks of 1TB each, we can store only 2TB of data in RAID 10 standard as 2TB data have its exact copy equivalent to 2TB.
- Striping of data with parity
- Read and write speeds are improved a lot
- Reliability is also improved
- 75% space can be used to store data
It is probably the most used RAID setup. RAID 5 array of disks make use of striping of data into different blocks with parity. Parity is an important piece of data which is used to rebuilt or recover the data in case any of the disk undergoes hardware failure. The parity is distributed evenly in all the disks.
But there is a downside as well, if we use four disks of 1TB each, the overall space we can use for storage of data is 3TB as equivalent of 1TB will be used to store the parity. It is fast, reliable and economical, in the same vein, it’s most used RAID setup.
Powercert Animated Video for RAID technology stands to be outstanding among all others. For instance, here you can understand the whole concept more easily.
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