Configuration
RAID 0, RAID 1 and RAID 10 RAID 10 configuration is also called RAID
1
+0 or RAID 1&0. It is a nested RAID level, which means it combines two standard RAID levels: RAID 0 and RAID 1. Let’s look at the configurations of these standard RAID levels, so we can understand how RAID 10 is built.
As shown above, RAID 0 uses striping, i.e. data is divided into blocks that are stored on multiple disks. This greatly increases read and write performance because data is already read and written in parallel across all disks. The disadvantage of RAID 0 is that there is no redundancy or fault tolerance. If one of the physical drives fails, all data is lost.
RAID 1 resolves redundancy, so if one of the drives fails, it’s easy to replace it by copying data from the still-functioning drives. However, the disadvantage of RAID 1 is the speed because it cannot take advantage of the parallelism that RAID 0 offers.
Now that we understand how RAID 0 and RAID 1 work,
let’s see how RAID 10 is configured
. RAID 10
, also known as RAID 1+0 is a combination of RAID 1 and RAID 0. It is configured as a strip of mirrors. The discs are divided into groups (usually of two); The disks within each group are images mirrored each other, while the data is divided into bands in all groups. Because you need at least two groups and each group needs at least two disks, the minimum number of physical disks required for a RAID 10 configuration is 4.
RAID 5 Configuration
Now let’s take a look at RAID 5 configuration
. RAID
5
uses parity information, unlike RAID levels 0, 1, and 10. For each combination of blocks, which are stored on different disks, a parity block is calculated and stored. Each individual parity block resides on a single disk; However, parity blocks are stored in a round shape on all disks. that is, there is no dedicated physical drive just for parity blocks (which is what happens in RAID 4).
Considering that the
data blocks are divided into at least two disks and the parity block is written to a separate disk, we can see that a RAID 5 configuration requires at least 3 physical drives
.
Redundancy and fault tolerance
Both RAID 5 and RAID 10 are fault tolerant, i.e. data is not lost even when one — or, in the case of RAID 10, more than 1 of the physical disks fails. In addition, both RAID 5 and RAID 10 can be used when replacing the failed disk. This is called hot swapping.
RAID 5
RAID
5 can tolerate the failure of 1 disk. Data and parity information stored on the failed disk can be recalculated using the data stored on the remaining disks.
In fact, data is accessible and reads are possible from a RAID 5 even when one of the drives has failed and is being rebuilt. However, such reads will be slow because some of the data (the part that was on the failed drive) is calculated from the parity block rather than simply read from disk. Data recovery and replacement disk rebuilding are also slow due to parity calculation overhead.
RAID 10 RAID
10
provides excellent fault tolerance, much better than RAID 5, due to the 100% redundancy built into its design. In the example above, disk 1 and disk 2 may fail and the data would still be recoverable. All disks within a RAID 1 group of a RAID 10 configuration would have to fail for data loss. The probability of 2 disks failing in the same group is much lower than the probability of either two disks failing in the RAID. That’s why RAID 10 offers higher reliability compared to RAID 5.
Failover is also much faster and easier for RAID 10 because data simply needs to be copied from the other disks in the RAID. Data is accessible during recovery.
Performance
RAID
10 offers fantastic performance for random reads and writes because all operations are performed in parallel on separate physical drives
.
RAID 5 also offers great read performance due to striping. However, writes are slower due to the overhead of calculating parity.
Pros and cons
Both RAID 5 and RAID 10 are hot-swappable, i.e. they provide the ability to continue reading from the array even when a faulty disk is replaced. However, in the case of RAID 5, such reads are slow due to the overhead of the parity calculation. But for RAID 10, such reads are as fast as they are during normal operation.
Other advantages of RAID 10 are: Very fast
- reads and writes Very fast
- More fault tolerant than RAID 5 because RAID 10 can tolerate failures of multiple disks at the same time.
failover Recovery
The disadvantages of RAID
10 are
: Costly due to
- inefficient storage (50%, due to duplication
) The advantages of RAID 5 include:
- Great balance between fault tolerance, price (storage efficiency) and performance
- Quick reads
The disadvantages
of
RAID 5 include:
- Slow recovery from failures
- It can only tolerate the failure of 1 unit in the Applications array
Considering the pros and cons, RAID 10 is useful in applications where performance is important not only for reads but also for writes. RAID 10 is also more suitable than RAID 5 in applications where it is critical to maintain performance during error recovery when one of the disks fails.
RAID 5 provides a healthy balance of efficient storage, decent performance, fault resistance, and good security. It is the most popular RAID configuration for enterprise NAS devices and enterprise servers. RAID 5 is ideal for file servers and applications that have a limited number of data drives. If the number of physical disks in the RAID is very large, the probability that at least one of them will fail is higher. Therefore, a RAID 6 may be a better choice because it uses two disks to store parity.
References
- Trade-offs between RAID 5 and RAID 10 storage configurations
- Nested RAID Levels – Wikipedia Parity in computing – Wikipedia Common RAID Disk Data Format (DDF) – Storage Networking Industry Association Solving Data Loss in Mass Storage Systems –
- Network Industry Association
- Storage
- Don’t be afraid of RAID
– Dell Standard RAID Levels – Wikipedia
