RAID Recovery™
Recovers all types of corrupted RAID arrays
Recovers all types of corrupted RAID arrays
Last updated: Dec 04, 2023

Difference between RAID 3 and RAID 4

RAID 3 and RAID 4, once popular choices among IT professionals and data centers, have largely fallen out of favor in contemporary settings, with RAID 5 and RAID 6 offering more advantageous features. Nonetheless, understanding these RAID levels remains valuable. RAID, or Redundant Array of Independent Disks, is a data storage configuration known for its distinctive storage capabilities.

RAID 3 is characterized by its use of data striping along with a single, dedicated parity drive. RAID 4 shares a similar approach, employing block-level data striping also with a dedicated parity drive. The primary distinction between RAID 3 and RAID 4 lies in their respective methods of distributing data and parity information across the drives.

What is RAID 3?

Put simply, RAID 3 is a type of Redundant Array of Independent Disks that supports byte-stripping of data and uses a dedicated parity drive. Byte-stripping implies that data passed on to the RAID storage is stripped in bytes instead of blocks, and then spread across the data disks. A copy of the data is also written into the dedicated parity disk.

The presence of a dedicated parity drive implies that when a drive fails on the array, you can still access your file. Yes, this is possible because when you try to access your data, the RAID will try to retrieve information about the data stored in the failed disk from the parity drive. Also, in RAID 3 data is transferred in bulk and access in parallel, so it is best for heavy-data environments.

But most IT experts are moving on from RAID 3 to newer RAID levels that are much easier to setup and offer better benefits. RAID 3 is a bit costly to setup and the configuration is quite complex. It compares with RAID 4 in that both utilize a separate drive to store parity data.

Disadvantages of RAID 3:

  • Reduced Performance for Small Data: RAID 3 performs well when you’re dealing with heavy data, but it slows down when you’re handling small data due to the data storage technique.
  • Possible Bottleneck: Because RAID 3 uses a single dedicated drive to store parity information, chances of experiencing a bottleneck are high.
  • Costly and Complex Setup: You will need to buy a separate drive to serve as the parity disk, which means additional cost. Also, RAID 3 is quite complex to set up.

Advantages of RAID 3:

  • High Data Read Speed: You may experience high data read speeds when you’re dealing with voluminous operations such as uncompressed video editing or other similar tasks.
  • Error Correction: The parity drive helps for error corrections. If there’s an error in the data being read, the RAID will try to pull up information from the parity drive and correct the error.
  • Fault Tolerance for Single Drive Failures: RAID 3 will still function very well even when a single drive fails in the array. But with more than one failed drive, your entire data could be lost.

What is RAID 4?

RAID 4 is a RAID level that utilizes a dedicated parity drive and supports block-level striping. It was introduced by the tech experts at Berkeley; while it has a quite sophisticated configuration, RAID 4 offers better performance than RAID 3 and it is best configured using SSDs for greater speeds.

Also, RAID 4 is much more flexible, it is one of those RAID levels you can extend the storage online without reconfiguring the parity settings. But for this to be possible, the new disk(s) must have nothing saved on them prior – they must be completely blank. The block-level stripping in RAID 4 means data is stripped in blocks (instead of bytes like in RAID 3) before getting saved across the data disks.

RAID 4 does not read information from the parity disk until one of the data drives fails. So, all the while, RAID 4 offers faster read speed as it only reads from the data drives. I/O requests run in parallel.

Disadvantages of RAID 4:

  • Slow Write Speeds: Since there’s a single parity drive and every data block needs to be written to the parity drive too, RAID 4 tends to have slower write speeds.
  • Possible Bottleneck: Just like in RAID 3, the single parity drive could lead to a bottleneck situation.
  • Uncommon: RAID 4 is very uncommon and rarely used in today’s data storage applications.

Advantages of RAID 4:

  • Faster Read Speeds: Because data is not read from the parity drive until one disk fails, RAID 4 tends to offer faster read speeds as data is read from only the data drives.
  • Fault Tolerance: RAID 4 can handle single drive failure, whereby the RAID tries to retrieve lost information from the parity drive.

Individual Block-Level Access: Due to the block-level stripping supported by RAID 4, data can be accessed in blocks from the individual disks.

RAID 3 vs RAID 4 Comparison

These two RAID levels are similar in many ways, but, they still contrast each other in many ways too. Hereunder is a table that clearly shows the difference between these two RAID levels.




Storage Pattern




Single disk parity

Single disk parity




Cost of Set Up



Modern Relevance



Performance and Speed

Fast read, slow write speed 

Fast read, slow write speed

Fault Tolerance 

Single disk failure

Single disk failure

Best Application

High data transfer tasks

High data transfer tasks

Data Recovery Differences in RAID 3 vs RAID 4

RAID 3 and RAID 4 function similarly, the only difference is the data-stripping technique – RAID 3 utilizes byte-stripping and RAID 4 utilizes block stripping. In a situation where one drive fails in the array, you will still be able to access all your files and data; this is because the RAID (whether RAID 3 or RAID 4) will try to read the lost information from the parity drive.

The recovery process in RAID 3 and RAID 4 are pretty much the same as they both use single dedicated drives for parity. When one drive fails in any of these RAID levels, it is advisable that you replace the drive and rebuild the array as soon as possible, or you stand the chance of losing every data you have stored on the RAID disks.

To replace a damaged drive in your RAID array, you should shut off the system remove the faulty drive and replace it with a new disk, then rebuild the array. There are different RAID rebuild software programs to use. If you delay replacing a failed drive in your RAID 3 or RAID 4, you stand to lose everything if another drive fails too. These RAIDS can only handle one drive failure.

How to Safeguard Your Vital Data?

The best way to keep your data safe is by backing them up to an external storage; it could be a cloud storage or another local storage. Interestingly, there are software programs that allow you to back up your RAID data for free – and as many times as possible. No matter the redundancy offered by your RAID level, it does not substitute for backups.

DiskInternals RAID Recovery is a professional software solution that helps you recover data from RAID arrays; it supports RAID 0 to RAID 6, as well as runs on all Windows OS and Server OS versions. This software is pretty intuitive to use and offers a “Disk Image” feature that lets you clone your RAID drives, and this can serve as your backup copies.

Making regular backups is a way to ensure you don’t lose any of your important files. You can also set up on-site solutions to help you with regular backups if you don’t want to use cloud storage or software programs.

DiskInternals RAID Recovery

  • Recovers data from corrupted RAID arrays, from RAID 0 to RAID 60
  • Supports RAID-enabled motherboards
  • Recovers lost data from NAS, Linux, Apple, and UNIX RAIDs
  • Save recovered files remotely via FTP or on a local storage
  • Mount virtual drives like local disk accessible by Windows Explorer

This is one of the best tools you can use to recover files from failed RAID drives. It can also recover your data even if the RAID controller is bad. The recovery wizard guides you through the entire process to retrieve your lost files, and you don’t need to pay until your files are recovered and preview them to confirm.


RAID 3 and RAID 4 are currently obsolete; their offers are part of what RAID 5 offers, so many would rather set up RAID 5 than one of these two. Also, the single parity drive utilized by these RAID levels isn’t reliable, so you should make backups often. DiskInternals RAID Recovery comes in handy as your reliable software program for recovering any data you lose from a RAID drive, regardless of the scenario.

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