RAID 5 vs RAID 10: Recommended RAID For Safety and Performance

A Redundant Array of Independent Drives (or Disks), also known as Redundant Array of Inexpensive Drives (or Disks) (RAID) is a term for data storage schemes that divide and replicate data among multiple hard drives. RAID can be designed to provide increased data reliability or increased I/O performance, though one goal may compromise the other. There different types of RAID levels. But which one you must use for data safety and performance considering that hard drives are commodity priced?

I did some research in last few months and based on my experience I started to use RAID10 for both Vmware / XEN Virtualization and database servers. A few MS-Exchange and Oracle admins also recommended RAID 10 for both safety and performance over RAID 5.

Quick RAID 10 overview (raid 10 explained)

RAID 10 = Combining features of RAID 0 + RAID 1. It provides optimization for fault tolerance.

RAID 0 helps to increase performance by striping volume data across multiple disk drives.

RAID 1 provides disk mirroring which duplicates your data.

In some cases, RAID 10 offers faster data reads and writes than RAID 5 because it does not need to manage parity.

RAID 5 vs RAID 10

For RAID 5 you need three minimum hard drive disks. For example:

  1. Level : RAID 5
  2. Number of disks: 3 (plus 1 spare drive)
  3. Drive size: 4000 GB
  4. Total RAID capacity: 8 TB
  5. Max fault tolerance: 1 disk
  6. Theoretical read performance: 2x
  7. Theoretical write performance: 1x (poor for small size write/files)
  8. Storage efficiency: 2/3 (66.7%)

RAID 10 you need for minimum hard drive disks. For example:

  1. Level : RAID 10
  2. Number of disks: 4 (plus 1 spare drive)
  3. Drive size: 4000 GB
  4. Total RAID capacity: 8 TB
  5. Max fault tolerance: 1 disk
  6. Theoretical read performance: 4x
  7. Theoretical write performance: 2x
  8. Storage efficiency: 1/2 (50%)

From Art S. Kagel research findings:

If a drive costs $1000US (and most are far less expensive than that) then switching from a 4 pair RAID10 array to a 5 drive RAID5 array will save 3 drives or $3000US. What is the cost of overtime, wear and tear on the technicians, DBAs, managers, and customers of even a recovery scare? What is the cost of reduced performance and possibly reduced customer satisfaction? Finally what is the cost of lost business if data is unrecoverable? I maintain that the drives are FAR cheaper! Hence my mantra:
NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5! NO RAID5!

Is RAID 5 Really a Bargain?

Cary Millsap, manager of Hotsos LLC and the editor of Hotsos Journal found the following facts – Is RAID 5 Really a Bargain?“:

  • RAID 5 costs more for write-intensive applications than RAID 1.
  • RAID 5 is less outage resilient than RAID 1.
  • RAID 5 suffers massive performance degradation during partial outage.
  • RAID 5 is less architecturally flexible than RAID 1.
  • Correcting RAID 5 performance problems can be very expensive.

My practical experience with RAID arrays configuration

To make picture clear, I’m putting RAID 10 vs RAID 5 configuration for high-load database, Vmware / Xen servers, mail servers, MS – Exchange mail server etc:

RAID Level Total array capacity Fault tolerance Read speed Write speed
RAID-10
500GB x 4 disks
1000 GB 1 disk 4X 2X
RAID-5
500GB x 3 disks
1000 GB 1 disk 2X Speed of a RAID 5 depends upon the controller implementation

You can see RAID 10 outperforms RAID 5 at a fraction of cost regarding read and write operations.

A note about backup

Any RAID level will not protect you from multiple disk failures. While one disk is offline for any reason, your disk array is not fully redundant. Therefore, old good tape backups are always recommended:

  1. FreeBSD Install Rsnapshot Backup Utility
  2. Debian / Ubuntu Linux Install Rsnapshot Backup Utility
  3. How To Install Rsnapshot on a Red hat / CentOS Linux
  4. 5 Awesome Open Source Backup Software For Linux and Unix-like Systems

Further readings:

Please add your thoughts and experience in the comments below.

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94 comments… add one
  • Noah Jun 16, 2016 @ 11:39

    You can’t have a general answer for all scenarios. There are cases, where RAID10 might be preferred and there are cases, where RAID5 (or any other RAID) might be better. You just should know the pros and cons and decide for your specific environment / application / need. That beeing said, you’re taking out an important factor out of the equation: cost-efficiency. Unless you’re a multi-million dollar enterprise and solve problems by throwing money at it, you will care about costs.

    In my case, I had to decide between a 4-disk RAID5 vs RAID10 with 2TB per disk for a home NAS. We’re talking about 4TB vs 6TB here, which is a 50% difference in storage. At the moment, 4.5TB are used and I’m glad I went for the 6TB RAID5. For a 6TB RAID10, I’d need to buy 2 more HDDs, for the same storage. Instead, I can save money and spend it on external backup solutions or whatever. And it pays out, the more storage you need.

    If performance is a concern for IOPS intense operations, you can still go for a cache enabled hardware RAID card (performance wasn’t a strong concern for me, cause gigabit network is the bottleneck anyways for file servers). Or simply go for a PCIe SSD (was probably not an option at the time of writing this article).

  • Max Nov 9, 2015 @ 17:40

    Raid 10 is work only 4 disk not 6 ? 4,8 ?

  • BISWA Aug 21, 2015 @ 11:08

    WHAT WILL WE DO IF WE ARE USING HOTSPARE FOR BOTH RAID 50 AND RAID 10 THEN SIMULTANEOUSLY DRIVE FAILS FROM BOTH RAID LEVEL THEN THAT MOMENT HOW THE HOT SPARE WILL WORK.???

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