Can you use any hard drive for RAID?

Quick Answer

Technically yes, you can use any hard drive in a RAID array, but there are some important factors to consider for optimal performance and reliability. The key things to look at are drive interface, capacity, rotational speed, and enterprise-level features.

What is RAID?

RAID stands for Redundant Array of Independent Disks. It is a data storage technology that combines multiple physical disk drives into one or more logical units. The main goals of RAID are to increase data reliability and/or improve performance.

Some key advantages of RAID include:

• Increased read/write performance – spreading data across multiple disks allows for simultaneous access.
• Fault tolerance – certain RAID levels allow for drive failures without any data loss.
• Extra storage capacity – RAID arrays can provide more storage space than a single disk.

There are several different RAID levels, each with specific data distribution and redundancy characteristics. Some common RAID levels are:

RAID 0	Stripes data across disks for faster reads/writes, but has no redundancy.
RAID 1	Mirrors data between two disks for redundancy, slower writes.
RAID 5	Stripes data and parity information across three or more disks, allowing for one disk failure.

The choice of RAID level depends on the goals for performance, redundancy, and storage capacity.

Drive Interface

One of the first considerations for a RAID array is the interface that the hard drives use to connect to the computer. There are a few common options:

• SATA – Serial ATA is the most popular interface for consumer hard drives and RAID arrays. SATA drives provide good performance and are cost effective.
• SAS – Serial Attached SCSI is a server-grade interface designed for enterprise environments. SAS offers faster transfers and more robust connectivity than SATA.
• NVMe – NVMe or Non-Volatile Memory Express is a high performance interface designed to utilize the fastest SSDs. NVMe offers unmatched bandwidth and low latency.

The interface used should match the capabilities of the storage controller or RAID card. Most consumer RAID arrays use SATA drives, while SAS and NVMe drives are more common in high-end servers and workstations.

Using mismatched drive interfaces in a single array is not recommended, as the faster drives will be bottlenecked by the slower interface. For optimal performance, all the drives should use the same interface type.

Drive Capacity

Drive capacity or size is another important variable. Here are some guidelines when selecting drives:

• Match capacities – For an array, all drives should typically have the same or very similar storage capacity. Mixing widely different sizes can lead to unused storage space.
• Larger is better – Bigger drives provide more storage efficiency and potential throughput for the array.
• Minimum vs maximums – Check storage controller specifications for any minimum or maximum drive size limitations.

In general, matching the highest capacity drives allows for the most flexibility and space in your RAID configuration.

Rotational Speed

The rotational speed of the hard drives, measured in revolutions per minute (RPM), directly affects performance. Some key considerations around RPM:

• Higher RPM = faster performance – 15,000 RPM is faster than 7,200 RPM, for example.
• Match RPMs – Having mismatched drive speeds can hamper RAID performance.
• SSDs have no RPM – Solid state drives have no moving parts, so RPM is not applicable. Their access times are extremely fast.

For RAID focused on faster data access, using higher RPM or SSD drives is recommended. Slower RPM drives like 5,400 RPM are best suited for storage-centric arrays.

Enterprise vs Consumer Drives

Hard drives designed for enterprise and server applications offer more robustness and reliability features compared to consumer models. Benefits of enterprise-class drives include:

• Higher workload tolerance – 24/7 operation, heavier workloads.
• Faster speeds – 10,000+ RPM spindle speeds.
• Better caching – Larger caches improve performance.
• Enhanced error correction – Reduces data errors and drive failure rates.
• Longer warranties – 5 years versus 2-3 years for consumer models.

These enterprise-level characteristics make server drives ideal candidates for mission-critical and high-performance RAID setups. The improved reliability can provide better uptime and data integrity.

Consumer drives are acceptable for home and small office RAID arrays where performance demands are lower. Their lower costs help make RAID more affordable in budget systems.

TL;DR

While nearly any drive can work in RAID, these criteria should be considered for optimal results:

• Match the RAID interface – SATA, SAS, NVMe, etc.
• Use same capacity drives
• Higher RPM and SSDs provide faster speed
• Enterprise drives handle heavy workloads and RAID better
• Consumer drives work for budget RAID arrays

Matching the components to the performance, capacity and redundancy needs of your RAID array will lead to a more effective system.

Can you mix and match different drive types in RAID?

You can technically combine different kinds of drives in a single RAID array, but doing so comes with some drawbacks:

• Performance imbalance – Faster drives have to run at the speed of the slowest drive.
• Wasted storage – Remaining space on smaller disks is unusable.
• Drive failures – If a smaller drive fails, the array capacity decreases.
• Complex management – Different drive sizes, ages and speeds makes maintenance harder.

Mixing drive types is generally not recommended for production RAID arrays. The preferred method is to use identical drives in terms of capacity, speed and other characteristics.

However, in certain home or testing scenarios, you may opt to combine mismatched drives in RAID modes like RAID 0, RAID 10 or RAID 50. These provide striping across disks which helps account for differences.

The bottom line – mixing drive types in RAID can work but requires accepting lower performance. Homogeneous drives make for a smoother RAID implementation.

Can you add different sized hard drives to RAID?

Adding hard drives of varying sizes to an existing RAID array is possible but has some caveats:

• Uneven arrays – Adding a smaller drive can leave unused space on other disks.
• Rebuilding issues – A smaller new drive may not be able to rebuild a larger failed drive.
• Performance impacts – Size differences can affect overall throughput.
• Logical drive size – The array capacity will match the smallest drive.
• Limits flexibility – Expanding the array in the future is more difficult.

For these reasons, it is best practice to add drives of the same size to a RAID configuration. Many RAID controllers only allow new drives of equal or greater capacity anyways.

An exception is RAID 10, which can tolerate size differences by mirroring pairs of any two drives. But in general, matching drive sizes is recommended for smooth expansion.

What happens if you mix HDD and SSD in RAID?

It is possible to create a RAID array combining both hard disk drives (HDDs) and solid state drives (SSDs). Here is what happens when you mix HDDs and SSDs in RAID:

• Performance imbalance – The SSDs can only run as fast as the HDDs allow.
• Wasted SSD capacity – Extra SSD space remains unused.
• Added cost – SSDs are more expensive than HDDs per gigabyte.
• Rebuilding issues – A failed HDD could take much longer to rebuild to an SSD.
• Disk contention – Both drive types competing for controller bandwidth.

The performance gains of adding SSDs to a HDD RAID array are usually modest. The SSDs end up bottlenecked while their fast capabilities go underutilized.

Mixing drive types can work, but for optimal performance it is better to create separate all-HDD or all-SSD arrays. Matching drive technologies provides a smoother RAID implementation.

Can you put different size SSDs in RAID 0?

You can technically configure RAID 0 with different sized solid state drives, but there are some downsides:

• Unused SSD space – The smaller SSDs have unused leftover capacity.
• Imbalanced stripes – Data stripes may not evenly distribute across different size drives.
• Performance limits – Array is constrained by the smallest SSD.
• No redundancy – RAID 0 offers no drive fault tolerance.
• Harder to expand – Adding more various sized SSDs makes expansion tricky.

For these reasons, it is advisable to use identically sized SSDs when building a RAID 0 array. This allows for optimal utilization of the fast SSD performance.

If using varying SSD sizes, the RAID 0 volume will default to the capacity of the smallest drive. Any extra space on larger drives becomes stranded and wasted.

While possible, mixing SSD sizes in RAID 0 comes with disadvantages. Using uniform SSDs is the better approach for smooth configuration and expansion.

What are the pros and cons of different sized hard drives in RAID 5?

Using different sized hard drives in a RAID 5 array is possible, though not typically recommended. Here are some potential pros and cons:

Pros:

• Inexpensive expansion – Can add cheaper, smaller drives over time.
• Use existing drives – Don’t have to buy all new matching drives.

Cons:

• Wasted space – Unused storage capacity on larger drives.
• Rebuild issues – A smaller new drive may fail before rebuilding a larger drive.
• Slower performance – Size differences can impact throughput.
• Complex management – Multiple drive sizes makes maintenance harder.

The cons generally outweigh the pros when it comes to mixing drive sizes in production RAID 5 arrays. Performance and reliable rebuilds suffer compared to using identical drives.

However, more leniency is possible in home or testing RAID 5 configurations where demands are lower. But for critical data, uniform RAID 5 drives remain the safest bet.

Can you combine two RAID 1 arrays into a RAID 10?

Yes, it is perfectly valid to combine two RAID 1 mirrored drive pairs into a RAID 10 array. Here is the process:

1. Create two separate RAID 1 arrays, each with two matched drives.
2. Use RAID software or hardware controller to build a RAID 10 array.
3. Add the two RAID 1 arrays as the components for the new RAID 10.

The end result is a RAID 10 configuration with enhanced performance and fault tolerance. This method provides an easy way to migrate existing RAID 1 mirrors over to a RAID 10 setup.

However, for best performance, the RAID 1 arrays should use drives of the same size and speed. Mixing drive types in RAID 10 is possible but not optimal. Starting from scratch with all new matching drives is ideal.

Can you add more drives to a RAID 10 array?

Yes, expanding a RAID 10 array’s total storage capacity is possible by adding more drives in matched pairs. Here is the general process:

1. Ensure the new drives are of same size and speed as existing drives.
2. Add the new drives in pairs to maintain the RAID 10 mirroring.
3. Let the RAID controller/software rebuild by mirroring the data to the new drives.
4. The total array capacity will increase once rebuild completes.

Most RAID 10 implementations allow gradual addition of drive pairs. However, some considerations include:

• Adding single drives is not possible – Must add in matched mirrors.
• Drive order may get shifted around.
• Rebuild times will be lengthy for larger arrays.
• Controller may have maximum drive number limits.

As long as drive pairs are added, expanding total RAID 10 capacity and redundancy is achievable. But large arrays may need more planning for smooth expansion.

Can You Use Different Speed Drives in RAID 0?

It is technically possible to combine hard drives with different rotational speeds in a RAID 0 array, but this comes with some downsides:

• Performance bottlenecking – The faster drives will need to run at the speed of the slowest drive.
• Imbalanced striping – Data distribution across mixed speed drives may be uneven.
• Increased risk of failure – Slower drives are more likely to fail before faster drives.
• No fault tolerance – RAID 0 does not provide any redundancy.
• Difficult troubleshooting – With drives of varying speeds, fixing issues becomes more complex.

For these reasons, it is best practice to use identical speed drives for RAID 0 arrays. Matching the RPM or using all SSDs will provide balanced performance across the full array.

Mixing drive speeds can work temporarily but makes it harder to optimize and maintain a RAID 0 set. Stick to uniform speeds for a smoother configuration.

Should all drives in a NAS RAID array be the same?

For a NAS (network-attached storage) RAID array, using all identical drives is strongly recommended for optimal performance and consistency. There are several benefits to matching drives in a NAS RAID:

• Avoid bottlenecks – Similar drives prevent faster ones from being limited.
• Maximize usable space – No wasted leftover capacity on smaller drives.
• Efficient rebuilding – Identical drives can rebuild failed drives faster.
• More reliable – Uniform drives tend to fail around the same time.
• Better throughput – Even read/write speeds across the full array.

NAS vendors like Synology, QNAP, Netgear, and Asustor all advise using the same make, model, speed and capacity drives when populating RAID arrays. This provides a smoother experience.

While it is possible to mix and match, keeping drives identical should be the goal for optimal NAS RAID performance and storage utilization.

Conclusion

In summary, while nearly any drive can technically work for RAID, using matched components is highly recommended for performance and reliability. Key criteria like drive interface, capacity, speed and features should be kept consistent across the array.

Mixing drive types in RAID can cause bottlenecks, wasted storage, rebuilds issues and other problems. For critical storage and production environments, uniform RAID drives are the safest path for smooth operations.

Consumers have more flexibility to combine mismatched legacy or spare drives in home RAID deployments where demands are lower. But for business and high-end configurations, keeping drives identical avoids difficulties down the road.

Carefully evaluate RAID requirements and select the optimal drives – buying in matched sets from the start makes maintaining and expanding the array much easier in the long run.