What is RAID?
RAID is an acronym for Redundant Array of Independent/Inexpensive Disks. The simplest way to think about RAID is that it allows multiple hard drives to be coupled together as a single larger storage capacity drive.
Aside from creating a single larger storage capacity drive from multiple smaller drives, RAID can also be used for various performance tasks like mirroring for data redundancy and protection or striping across drives to increase write speed and read speed. This is done through RAID array levels that inform the RAID system on how to use the drives installed.
Here is a list of the RAID levels you can choose from:
- RAID 0: Data striping with no mirroring or parity.
- RAID 1: Data mirroring with no parity or striping.
- RAID 2: Bit-level data striping with Hamming-code parity.
- RAID 3: Byte-level data striping with dedicated parity.
- RAID 4: Block-level striping with dedicated parity.
- RAID 5: Block-level striping with distributed parity.
- RAID 6: Block-level striping with double distributed parity.
If you’re unfamiliar with the terms used for data handling on RAID systems, here are a few quick definitions to get you up to speed.
Striping is the process of writing file contents across multiple drives within an array.
Striping data is the base process that allows RAID arrays to form a single large storage capacity drive out of smaller drives. Put simply, it cuts files that need to be written to the array into small sections on the bit, byte, or block-level and writes them in pieces across each drive in the array. RAID 0 is the only RAID level to use striping with no parity or mirror function. This is useful for increasing storage capacity, but if a single drive in the array fails the entire set fails.
Disk Mirroring is the process of replicating/cloning a logical disk volume onto separate storage drives in real-time.
Mirroring is a basic redundancy function that allows the user to maintain exact duplicates of an entire disk drive across as many other drives as needed in the RAID drive set in real-time. This process ensures that if one drive fails, there’s a complete backup to restore it with.
Parity is the simple error detection code used to confirm data integrity.
As striping data across multiple drives can lead to problems with heavy use, parity codes were created to help track data integrity. Different RAID levels use different parity methods.
What is RAID 0?
The RAID 0 level is a simple setup that combines the storage disks into the array into a single logical drive. It writes and reads across the multiple drives through stripes of data. RAID 0 has no parity which means it is a quick and dirty way to make a pile of small hard drives into a single large capacity drive. Unfortunately, this means that if any drive fails the entire array fails.
The upside to a RAID 0 array is that it can greatly increase the performance of the read/write speeds of the drives in the array. As striping moves from one drive to another, it can break down the file content and save stripes simultaneously. The more drives in the array, the faster the write/read speeds.
Here are the key features of RAID 0:
- High performance
- Stripped volume with no fault tolerance
- Two or more disks required
- No parity disk
- Inexpensive overall cost
What is RAID 1?
RAID 1 is designed for mirroring/cloning an entire volume onto one or more other disks in real-time. It provides great data security and fault tolerance through data redundancy. If the original disk is damaged or fails in any way, it can be restored with a mirrored disk.
This array requires that each storage disk is at least as big as the smallest drive as it retains an exact copy of the original disk and requires the exact amount of space. If any drive in the array fails, it will continue to work properly. Failed drives should still be replaced to maintain data redundancy.
Here are the key features of RAID 1:
- Volume mirroring with fault tolerance through redundancy
- No parity disk
- Two or more storage drives required
- High data security
- Can be expensive as each mirrored volume must be the same storage capacity as the original drive.
Similarities Between RAID 0 and RAID 1
Aside from both being RAID arrays, there are a few other similarities between the two. Both require at minimum 2 storage drives. Both use a singular method of RAID arrays, one uses only striping and one uses only mirroring. Neither use parity code nor require a parity disk.
While these similarities may lead some to believe that the two are interchangeable, the two arrays function completely differently.
RAID 0 vs RAID 1: Side-by-Side Comparison
|RAID 0||RAID 1|
|What it is:||RAID array level||RAID array level|
|Primary Use:||Direct data management of disk drives|
Direct data management of disk drives
|Technical Committee:||David Patterson, Garth A. Gibson, Randy Katz||David Patterson, Garth A. Gibson, Randy Katz|
|Technologies Influenced:||Servers, Hard Drives, Virtualization||Servers, Hard Drives, Virtualization|
|High performance (fast write speeds and read speeds)||No parity|
|Stacks smaller drives into a single logical volume||No data fault tolerance|
|Budget-friendly||One disk failure leads to array data loss|
|Fastest RAID array|
|High data security||No parity|
|Provides fault tolerance through data redundancy||More expensive than RAID 0|
|Drive failure does not lead to data loss and array failure||No performance improvement|
|Most overall cost fault-tolerant system|
Differences Between Them
The largest of the differences between RAID 0 and RAID 1 comes down to their primary data storage functions. In other words, RAID 0 and RAID 1 handle storage drives completely differently. RAID 0 puts all of the drives in the RAID array into one single logical volume. That turns a set of small drives into a single large volume. RAID 1 copies a primary drive to one or more other drives in the array bit-for-bit in real-time.
The differences between these two functions alone make RAID 0 faster for read/write operations with a lower overall cost and RAID 1 a much safer option for data safety and integrity. For this reason, comparing the pros and cons of each array against the other isn’t the best way to decide which to use.
When to use RAID 0 or RAID 1
RAID 0 is not generally recommended as it is the highest risk of an array failure. However, it can be useful for applications that require the fastest read/write speeds like 3D modeling or PC gaming. It can quickly turn a set of small drives into a single high-performance volume.
RAID 1 is a basic data security array that allows the user to copy the contents of the main drive in the array in real-time. This is perfect for applications that require high data security and fault tolerance like development and personal records.
RAID 0 vs RAID 1: Six Must-Know Facts
- RAID 0 uses only striping, while RAID 1 uses only mirroring.
- Both RAID 0 and RAID 1 require a minimum of 2 drives.
- RAID 0 allows for multiple drives to stack into a single virtualized storage volume.
- RAID 1 maintains an exact duplicate of the main drive on other drives in the array.
- RAID 0 allows for faster performance and has less system cost.
- Neither RAID 0 nor RAID 1 use parity code or a parity disk.