Does RAID 5 Configuration Give You Faster Transfer Speed Versus RAID 1 Mirroring Configuration?

Raid configurations serve different purposes and performance characteristics. This article provides a comprehensive comparison between RAID 5 and RAID 1 in terms of transfer speeds, read operations, and write operations.

RAID 1 Mirroring Configuration

With RAID 1, data is duplicated across two or more disks. This duplication offers several benefits, particularly for read operations.

Read Speed: Reads can be faster because the system can read from multiple disks simultaneously, effectively allowing for parallel read operations. Write Speed: Generates slower write speeds, as data must be written to every disk in the array, which is a limitation compared to RAID 5.

RAID 5 Striping with Parity Configuration

RAID 5 implements striping (data spread across multiple disks) with parity. This configuration offers higher redundancy and performance compared to RAID 1, especially for read operations.

Read Speed: Typically faster than RAID 1, particularly as the number of disks increases, due to striping, which allows multiple disks to be read simultaneously. Write Speed: Slower than RAID 1, primarily due to the necessity of simultaneously writing data and calculating and writing parity information, which adds overhead.

Conclusion

In general, RAID 5 can provide better read performance, especially as the number of disks increases. However, for write operations, RAID 1 may perform better due to the lack of parity calculations. The choice between RAID 1 and RAID 5 should also consider redundancy needs, available disk space, and the specific workload characteristics.

Generality: Generally, RAID 5 will give a little higher transfer rate on read operations and a fair bit on write operations. The read difference tends to be a “benchmarks only can tell” thing, while the writes can be quite noticeable.

Read vs. Write Performance: RAID 1 can share a read instruction between all the disks, each doing a small portion effectively reading from multiple sources at once. With RAID 5, at least one disk is not forming part of this team, making read operations slower. If RAID 5 has parity checked reads enabled, there is an additional overhead in calculating the data from each read, making it certainly slower. However, for RAID 1, it needs to send exact same instructions to all disks, each one doing the exact same work, which is bounded by the slowest drive in the set.

Overhead of Parity Calculation: This "extra overhead" of parity calculation changes the speed differential between RAID 5 and RAID 1, particularly by the amount of disks. A RAID 1 of 3 disks might be slightly faster even for writing than a RAID 5 of 3 disks. However, a RAID 5 with 4 or more disks may pull ahead due to the overhead of parity calculation.

Intermediary Factors: 'Transfer speed' isn't just about how the drives are arranged and connected. The act of 'transfer' means there is at least one intermediary between endpoints, such as a cable or a network bottleneck. Each point could influence the maximum speed you see. This includes the SATA controller, the processor on the RAID card, or the CPU when doing software RAID.

Hardware Limitations: RAID speed is limited by the hardware used to join the disks. A SATA controller should be able to handle up to 600MB/s, capable of handling several hard drives. Adding more drives into the same controller or using SSDs can make the controller the bottleneck, as drives can individually send/receive much faster than a single controller.

Expansion and Performance: Previously, SSD RAID was a bottleneck issue, as even adding a second drive did not improve speed. However, with newer NVMe/PCIe connections and faster SSDs, single controllers are now less of a limitation. If drives exceed the single controller's limits, ensure they are connected on separate controllers.

Therefore, it's crucial to ensure the RAID setup is configured to optimize performance and meet the specific needs of the workload.