Deciding Between RAID 5 vs RAID 10: An In-Depth Comparison

Choosing the right RAID level for storage is crucial to meet performance, capacity, and resilience requirements. Two of the most versatile options include RAID 5 and RAID 10. Let‘s unpack what each offers and dive deeper on their pros, cons and ideal use cases.

First, what exactly is RAID? It stands for Redundant Array of Independent Disks – which is a virtualization method that combines multiple physical drives into logical units. The different standard RAID levels use various techniques like:

  • Striping: Segmenting data sequentially across drives
  • Mirroring: Creating duplicate copies of data
  • Parity: Error detecting checksums for redundancy

Common RAID levels utilize one or more of these to deliver different benefits:

RAID 0 – Striping for pure performance
RAID 1 – Mirroring for total redundancy
RAID 5 – Block-level striping with distributed parity
RAID 10 – Striping over mirrored spans for speed + redundancy

Now let‘s explore RAID 5 and RAID 10 to understand their strengths and weaknesses.

Diving Deep on RAID 5

RAID 5 stripes blocks of data and parity information across a minimum of three drives. The parity allows the array to sustain a single drive failure without data loss. When a failed drive gets replaced, the RAID rebuild process reconstructs the data and parity back onto the new replacement.

However, rebuilds take a very long time with RAID 5 since all data blocks must be read to recalculate parity. Performance degrades significantly during this rebuild time. The larger the drives, the longer RAID 5 rebuild times will be.

RAID 5 (minimum 3 drives)

Data - Data - Parity
Data - Data - Parity 
Data - Data - Parity
Data - Data - Parity

Total usable capacity is the sum of all drive capacities, minus one drive worth used for parity.

For example, three 4 TB drives would give you 8 TB total capacity.

When Does RAID 5 Perform Well?

With a lower parity calculation overhead, read performance can be very good with RAID 5 since the multiple drives can operate in parallel.

But write performance and latency suffer compared to RAID 10 as each change must read old data and parity, update parity, then write the new data and parity blocks.

Consequently, RAID 5 best suits use cases like:

  • Media storage with mostly sequential reads
  • Backups or archives rarely needing updates
  • Budget environments prioritizing capacity

However, the parity overhead along with rebuild times make RAID 5 a poor fit for transactional or "write-heavy" workloads like databases.

Understanding RAID 10 Benefits

RAID 10 combines mirroring for fault tolerance along with striping for parallel performance. It requires a minimum of four drives, configured as two identical pairs:

PAIR 1                 PAIR 2

Drive 1 - Drive 2    Drive 3 - Drive 4 
(Mirrored)              (Mirrored)

Striped Across Pairs:

This layout can handle multiple drive failures – as long as no more than one failure happens per mirrored pair. If a drive fails, the rebuild time is very fast since the data can simply get copied from the mirror drive.

Compared to RAID 5, write performance and latency are excellent given RAID 10 only needs to stripe/mirror data with no parity calculation overhead.

The tradeoff is usable capacity equals 50% of the raw drive capacity in RAID 10. With those same four 4 TB drives, total RAID 10 capacity would be 8 TB.

When to Choose RAID 10?

RAID 10 is preferred for applications needing high availability along with fast transactions. For example:

  • Database servers
  • Virtualized environments
  • Critical business systems
  • High performance compute
  • Smaller capacity requirements

If application performance and uptime are vital, RAID 10 provides superior redundancy and speed. The mirroring avoids rebuild performance hits while striping accelerates reads and writes across multiple spindles.

Comparing Key Specifications

SpecificationRAID 5RAID 10
Minimum Drives34
Raw CapacitySum of all drivesSum of all drives
Fault Tolerance1 drive failure1 failure per mirror
Rebuild TimeLongVery fast
Read PerformanceHigh (parallel drives)Highest (striping over mirrors)
Write PerformanceModerate (parity overhead)Excellent (mirroring only)
Cost EfficiencyHighLow (50% used for redundancy)
Database SuitabilityLowHigh

So in summary:

  • RAID 10 emphasizes performance, redundancy, and rebuild times
  • RAID 5 focuses on overall capacity with good reads

When choosing RAID levels, first define availability, performance and capacity goals. Mixing RAID types across drives or enclosures can also optimize for budget while meeting application needs. Work with solution providers to map the ideal RAID layout based on workload priorities and constraints.

I hope this deep dive helps provide more context to choose the right RAID for your next project! Let me know if you have any other questions.

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