Frequently Asked Questions About RAID 5 Versus RAID 6

RAID 6 is better than RAID 5 because RAID 6 offers a higher tolerance to disk failure. In other words, RAID 6 provides better data security than RAID.

As you have read in this guide from the beginning, RAID 6 can rebuild both a single disk and two disks when they fail. On the contrary, RAID 5 can only handle a single disk failure.

RAID 5 is obsolete in a sense. In terms of capability, RAID 5 combines striping with parity alone.

Meanwhile, RAID 6 is an extension of RAID 5 and it performs more than RAID 5. It combines striping with double parity, and this difference has some effects on their performance.

Simply put, the newer RAID 6 has a better capacity to handle disk failure.

RAID 5 is a bit faster than RAID 6 in reading (opening) and writing (saving) files. So, It is ideal for file and application servers that care more about data read/write speed than failure tolerance.

RAID 6 is still a good configuration of disks for most file servers today. You’ll appreciate this especially when you consider the major target of RAID 6 – speed and data security.

RAID 5 carries higher risks of encountering an uncorrectable drive error during a rebuild. So, it does not offer optimal data protection.

Therefore, RAID 5 is not recommended for storing business-critical data.

For data recovery, RAID 6 is better because it can recover from 2 simultaneous disk failures.

However, it is more expensive to implement as it requires RAID hardware. Also, compared to RAID 5, It sacrifices 2 disks required for parity information.

Additionally, because RAID 6 needs to calculate a second parity data, RAID 6 is marginally slower than RAID 5.

You lose 2 drives in a RAID 6 configuration. A RAID 6 array requires a minimum of 4 disks – 2 are reserved for parity information.

On the contrary, a RAID 5 array requires a minimum of 3 disks with 1 disk reserved for parity.

The read performance of a RAID 5 array is very close to that of a RAID 6.

However, the write performance of a RAID 6 array is slightly slower due to the time spent in calculating double parity.

In a RAID 5 array, you lose the size of one disk in the array.

As an example, for a RAID 5 array with four 512 GB drives, the total capacity of the array is:

(4-1)*512 GB = 1536 GB (1.536 TB).

Ordinarily, four 512 GB drives should give:

4*512 = 2048 GB (2.048 TB).

For data recovery, RAID 6 is the safest as the array is able to recover from 2 simultaneous disk failures.

On the contrary, a RAID 5 array can only recover from a single disk failure. In a RAID 5 array, if 2 disks fail at the same time, recovery may be impossible.