RAID 4 or 5 - Which Is Better?
Redundant Array of Independent Disks (RAID) is a storage technique adopted by most IT experts and companies to enable faster performance, data parity, and redundancy. There are many known types of RAID; they are identified by numbers 0, 1, 2, 3, 4, and so on. Each RAID type offers a unique data storage and processing technique.
Talking about RAID 4 and RAID 5, these are two different – yet similar – RAID types. They both promise better performance, but that depends on how you set up the array. In this article, we will compare and contrast the similarities and differences between RAID 4 and RAID 5. A quick tip is that both RAID types support parity, but not in the same manner.
What is RAID 4
RAID 4 is a type of RAID type that supports block-level striping and runs with a dedicated parity disk. This RAID type was originally introduced by tech experts at Berkeley; it has a quite sophisticated setup and is preferably configured using SSDs so you can get considerably high-speed transfers.
One huge advantage of RAID 4 is its flexibility – you can extend the storage online without recomputing the parity, however, the newly added disks must be completely empty with no data. In RAID 4, each drive in the array operates independently and data is saved across the disks via block-level striping; this means data is striped in blocks of variable sizes before getting stored.
Due to the independency of RAID 4 disks, I/O requests run in parallel and this could mean higher performance depending on the application. But then, this RAID uses a single drive for parity, the performance speed isn’t so fast as that of RAID 5.
Disadvantages of RAID 4:
- Uses one single drive for parity, and this reduces the speed to an extent compared with other RAID types.
- The setup is a bit complex, not many people prefer it over RAID 5
- Small file requests run slowly on RAID 4 because data needs to be stripped in blocks and transmitted in parallel.
Advantages of RAID 4:
- You only need a minimum of two disks to set up RAID 4: one disk for data stripping and another for parity. This makes RAID an affordable alternative for some people.
- RAID 4 provides faster performance when handling large sequential files than small random files.
What is RAID 5
RAID 5 is a type of RAID setup that equally supports block data striping and parity. But unlike in RAID 4 where a single parity drive is used, in RAID 5, parity data is spread across the disks in the array. This cross-sharing of parity data makes RAID 5 offer a seemingly better performance coupled with higher transfer speeds.
Also, since there is no single parity drive that may fail, RAID 5 can handle drive failures without your files getting lost. When a single drive drives in RAID 5, subsequent reads can be calculated from the distributed parity; don’t mistake this for data backup, if another drive fails, you could lose everything.
To set up a RAID 5 array, you need a minimum of 3 disks. RAID 5 could feature many data layouts, depending on how data is written across the disks. RAID 5 is generally faster than RAID 4 because of the distributed parity; a single parity disk can create a data input bottleneck, which is a common problem with RAID 4.
Disadvantages of RAID 5:
- RAID 5 has a write penalty calculated to be four. This is because, RAID 5 reads the data on the drives, then goes on to read the parity, returns again to write the data, and finally, writes the parity; four operations for each effective one
- When rebuilding RAID 5, you’ll notice a significant performance decline, especially when disks of different sizes are used.
Advantages of RAID 5:
- RAID 5 can handle single drive failure perfectly; the RAID will attempt to read the lost data from the distributed parity data.
- Due to its distributed parity technique, there’s more space for primary data to be stored across all drives used in the array.
- RAID 5 replaced RAID 2 to 4 and provided the footprint for modern-day RAID levels. It offers better performance and redundancy than RAID 2 to 4.
Comparison Table RAID 4 vs RAID 5:
These two RAID levels compare to one another in many ways and below is a table that makes it clearer to understand their differences.
Single disk parity
Minimum No. of Disks
Cost of Set Up
Not obsolete but rarely used
Performance and Speed
Single disk failure
Single disk failure
High data transfer tasks
High data transfer tasks
A single drive failure will reduce the performance of RAID 4 and RAID 5, and if another drive goes on to fail before you could rebuild the RAID or replace the first damaged disk, then you’re SCREWED. The dedicated parity disk on RAID 4 slows down write speeds but does not affect read speeds.
Data Recovery Differences in RAID 4 vs RAID 5
In RAID 4, the failsafe information stored in the parity disk is only ever retrieved when one of the data disks fails. For the rest of the time (when all drives are in good condition), RAID 4 will only read from volumes on the data disks, which makes it perform faster – up to 20% better than RAID 5, especially when SSD or NVMe drives are used.
In RAID 5, the parity information is written into the same drives where the primary data is saved. Now, because the parity data is saved on the data disks, RAID 5 takes a little more time to read data from the drives because it needs to read the parity information too, which actually is not important until there’s a failed drive in the array.
But then, regardless of the RAID level you choose to set up, you should never play down the role of regular backups. Fault tolerance and parity data calculations do not equate to backup, peradventure multiples disks fail at once in the array, your entire data in the RAID is screwed – with minimal possibility of getting them back.
How to Safeguard Your Vital Data?
You should also monitor the health status of the disks in your RAID array to know when they start going bad, so you can fix or replace them on time. But then, the best way to ensure that your important files and data are safe and preserved is by backing them up externally – to a cloud storage or another local storage.
Regular data backups provide you with the safest failsafe haven to fall back on in times of data loss. So, even if multiple disks fail at the same time in your RAID array, you’re sure your vital data are still retrievable – from backup. A reliable RAID backup solution for Windows OS users is DiskInternals RAID Recovery software.
DiskInternals RAID Recovery
This software lets you clone your RAID drives in disk image format and the image files to serve as your backups. You can create multiple disk images at any time – for free. It doesn’t stop there, the DiskInternals RAID Recovery is primarily a data recovery solution for RAID users; it can recover data from any RAID array and it supports a wide variety of RAID controllers.
DiskInternals RAID Recovery runs on all Windows OS versions and utilizes very minimal system resources. The interface is intuitive and there’s a wizard interface that guides you through recovering your lost RAID data using this program. Whether your RAID disk got dead or the controller is damaged, DiskInternals RAID Recovery can help out.
Literally, in all respects (aside from how they store and deal with parity data) RAID 4 and RAID 5 are identical. If you must choose between these two, RAID 5 is a better option. However, you may love to consider RAID 6 or RAID 10, which tend to offer higher levels of redundancy and performance.