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Raid 10 vs Raid 5

by Kevin Bellah

The redundant array of inexpensive/independent disk (RAID) allows you to utilize a group of physical hard disks that appear as a single area of usable space on your PC. This combination enables reliable data storage in the background so you can have fault tolerance, speed, and redundancy. Since previous RAID levels have become obsolete, this comparison focuses on RAIDs 5 and 10.

RAID 5

RAID 5 is somehow an improvement of its predecessor RAID 4. Just like RAID 4, RAID 5 is stripped at a block level and has dedicated parity disk. The parity disk enables data recreation if one of the disks fails. Since RAID 4 has only one parity disk, you will likely experience a slight delay in writing operations. Thus, it’s far more efficient to go with RAID 5, which doesn’t require spinning and sync.

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Instead of allocating a full-disk space on a single dedicated parity drive, RAID 5 distributes parity across all drives. The RAID 5 distributed parity space will still occupy a similar space as in RIAD 4, but it enhances efficiency by storing across the disks. So, if one disk was to fail, you can reconstruct the information from the records on other drives and the parity disk. RAID 5’s block-level stripping offers good performance and is probably the most cost-effective solution since it takes the space on only one disk for any number of drives. Despite this, you should expect slow operations as the controller rewrites parity information from other drives. Overall, RAID 5 is perfect for databases.  

RAID 10

RAID 10 is nested RAID 1+ RAID 0 because it applies both setups. 

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RAID 0 stripes its data across the disks enabling it to read multiple data points from multiple disks simultaneously. In simple terms, disks in RAID 0 levels store different parts of the same data. Therefore, losing a single disk would lead to the loss of some parts of the data. While RAID 0 is known to provide exceptional speed, it could be unreliable, especially for a mission-critical system.

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As you can see from the diagram above, RAID 1 seems to mirror or duplicate data from one disk to the other. The data duplication enables data recovery in case of disk failure making RAID 1 ideal for reliability.

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Going back to RAID 10, single disk failure won’t screw up your system because you have the backup in one of RAID 1’s drives. You also enjoy the level of performance with the RAID 0 stripes. However, you remain with half the usable space, so four disks would give you two-disk space. Nonetheless, RAID 10’s efficiency is based on the fact that you would need a pair of drives to fail for the system to mess up because it’s a nested level. 

RAID 5 and RAID 10 Features and Advantages

Fault Tolerance

Both RAIDS 10 and 5 can survive one-drive failure. However, RAID 10 builds the array faster by copying the remaining good data from the second mirrored set, so it has minimal performance on your network-attached storage (NAS). On the other hand, RAID 5 has to pull data from all the remaining drives to rebuild the bad one, which is time-consuming, not to mention the severe impact on performance. 

Performance

As for speed, RAID 10 is a clear winner here as it can have four times the read performance and twice the write performance over a RAID 5 configuration. Unfortunately, that’s not the reality on most low to medium NAS units.  The unit’s controller performance and saturation hugely impact the theoretical speed gains, especially if you use faster drives such as solid-state drives (SSDS). 

Minimum Number of Drives

RAID 5 has a clear advantage here as you only need 3 drives to create an array and at least four drives for a RAID 10 configuration. So, if you want to expand your four-bay RAID 10 NAS, you’ll have to add an expansion unit or replace all four drives. In RAID 5, you only need to add a drive to that empty slot to expand your storage, making it more efficient. Remember that RAID 10 requires additional drives in pairs, whereas RAID 5 allows one extra drive at a time. 

You really need to maximize how much storage you can get on your device, especially for archives and the likes. If you have a massive storage base, RAID 10 might not be a problem, but it’s an issue in NAS units. RAID 10 and RAID 5 have a different configuration that impacts their reliability, speed, and performance. The detailed comparison seeks to help you decide on the suitable RAID level depending on your storage purpose.  

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