RAID 1 vs. RAID 5: Five Must Know Facts
- RAID 1 is used to mirror, or duplicate, one drive to another in real-time.
- RAID 5 puts multiple drives into a single logical drive and spreads the written data in blocks across each drive.
- RAID 1 has no form of information parity or striping.
- RAID 5 does not mirror information to other drives.
- Both 1 and 5 arrays can be set up on nearly any RAID setup.
What Is RAID?
RAID stands for redundant array of inexpensive/independent disks. It is a data storage virtualization technology that manages multiple physical disk drive components as one or more logical units. The point is to increase data redundancy for security and stability as well as to improve server performance.
Data is distributed across the available drives in one of several ways known as RAID levels. Each RAID level provides a variation to reliability, availability, performance, and capacity. The different RAID levels to know are:
- RAID 0: Uses striping with no mirroring or parity.
- RAID 1 Mirrors data with no parity or striping.
- RAID 2 Bit-level striping with Hamming-code parity.
- RAID 3 Byte-level 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.
Striping is a process that distributes the contents of each file across all of the drives connected in the RAID set. Disk mirroring is the process of replicating logical disk volumes onto separate drives in real-time. Parity is a simple form of error detecting code.
Striping data across multiple drives in a RAID set allows for expanded storage. This is only useful for using a set of hard drives as a single logical drive as striping alone as in a RAID 0 level relies on drive stability. If any drive in a RAID 0 set fails, the logical drive fails. The benefit to this process is an increased throughput of reading and write operations multiplied by the number of storage drives in the RAID set.
Mirroring is a redundancy feature meant to improve the security of drive data by creating copies. This can help keep your data safe if you happen to experience a drive failure as the mirrored drive contains the exact same information.
What Is RAID 1?
RAID 1 uses only data mirroring. One drive can be selected out of the RAID set to copy to one or more other drives in the set. This creates an exact duplicate of the files on the original drive. This level is often used to increase data security. It can also be used to increase open access to a set of information. As each drive has a limit to its read/write speeds, multiple users can access information quicker with mirrored RAID drive by causing less stress on the main drive.
A RAID 1 array remains functional as long as one drive is still working. That means drives in the set that fail can be quickly replaced with no data loss and only a small amount of downtime.
What Is RAID 5?
RAID 5 uses block-level striping with distributed parity code. That means it stores blocks of information across separate drives along with parity information. In order to set up a RAID 5 array, you must use three separate physical hard drives.
RAID 5 helps to increase operation speed by using multiple drives throughput to write blocks of information. This means a single file or program can be distributed across a minimum of three hard drives quickly. The benefit is increased data read/write speeds which speeds up project time and overall performance.
RAID 1 vs. RAID 5: Side-by-Side Comparison
As there is no real price difference between setting up a RAID 1 or RAID 5 array, you’ll need to weigh the pros and cons of each array to determine which array best fits your applications. This section will give the similarities and differences between the two.
| RAID 1 | RAID 5 | |
|---|---|---|
| What it is: | RAID array level | RAID array level |
| Primary use: | Mirroring Storage for backups | Increasing read/write performance and combine multiple drives into a single logical drive |
| Conceived: | 1977 | 1986 |
| Initial release: | 1988 | 1986 |
| Technical committee: | IBM | IBM |
| Influential developers: | Norman Ken Ouchi, David Patterson, Garth A. Gibson, and Randy Katz | IBM |
| Open format: | Yes | Yes |
| Technologies influenced: | HDDs, SSDs, Servers | HDDs, SSDs, Servers |
Configuration Differences
RAID 1 arrays can be set up with only two drives in the RAID set. One drive is used as the primary while the second keeps an exact copy of the first. This process runs at the same speed the drives are capable of reading/writing at.
RAID 5 requires multiple drives to stripe across and one drive to hold parity bits and service information to restore the array in the case of disk failure. You’ll need a minimum of three drives in the RAID set to make a RAID 5 array.
Read/Write
RAID 1 arrays read/write at the same speed as a single disk, sometimes a little higher due to writing to multiple disks simultaneously.
RAID 5 has a slower write speed as time is spent calculating blocks to slice and where to put them along with recording checksum on a separate disk. However, the read speed on RAID 5 is fairly quick.
Fault Tolerance
RAID 1 arrays allow for complete redundancy and information protection. As one drive fails, the information is completely accessible on the mirrored drive or drives.
RAID 5 stores data and parity information between three or more disks. That means if a disk failure were to render a RAID 5 setup one drive short, the array will collapse and fail. However, data recovery can be done in a RAID 5 array much quicker than RAID 1 as only blocks of information are stored on each drive rather than a complete mirrored set.
Performance Differences
RAID 1 arrays require more than one mirrored drive to see an increase in performance. It’s still not the greatest in terms of speed, but speed is the price you pair for data security.
RAID 5, on the other hand, has seen disk controllers improve to the point that it can be considered a fast and productive array. The write speeds aren’t the greatest, but the read speed is perfect for continuing to access stored data.
Storage Capacity
RAID 1 will be limited to the storage capacity of the main mirrored drive. As the array is meant to maintain duplicates for redundancy and security reasons, all drives would need to be increased in capacity to increase the array capacity.
RAID 5 takes all but one of the drives in the RAID set and creates a single consistent logical drive. That means if you have the minimum setup of three drives, two-thirds of the total capacity is the RAID data storage capacity.
