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How to choose between different RAID?
Overview
RAID (Redundant Array of Independent Disks) is a data storage technology that allows multiple hard drives to be combined into a single storage unit.
Depending on your environment and model, Synology NAS supports various types of RAID levels for you to choose from. Each RAID type provides different strengths, such as varying levels of performance, capacity, and reliability.
The article will provide a brief overview of RAID types supported by Synology NAS, including implementation requirements and advantages/disadvantages, so you will be able to choose the RAID type that best suits your individual needs.
Contents
1. RAID Types Supported by Synology NAS
This table provides a brief overview of different RAID types supported by Synology NAS, including the following details: storage capacity; the minimum number of hard drives; and the number of hard drive failures that can be tolerated before data loss occurs.
| Volume Type | Number of HDD | Tolerable Disk Failures | Description | Volume Capacity |
|---|---|---|---|---|
| SHR | 1 | 0 |
|
1 x (HDD size) |
| 2-3 | 1 | Optimized by the system. | ||
| ≧4 | 1-2 | |||
| Basic | 1 | 0 |
|
1 x (HDD size) |
| JBOD | ≧2 | 0 |
|
Sum of all HDD sizes |
| RAID 0 | ≧2 | 0 |
|
N x (Smallest HDD size) |
| RAID 1 | 2-4 | 1 |
|
Smallest HDD size |
| RAID 5 | ≧3 | 1 |
|
(N – 1) x (Smallest HDD size) |
| RAID 5+spare | ≧4 | 1 |
|
(N – 2) x (Smallest HDD size) |
| RAID 6 | ≧4 | 2 |
|
(N – 2) x (Smallest HDD size) |
| RAID 10 | ≧4 (even number) |
Half of the total HDD |
|
(N / 2) x (Smallest HDD size) |
- RAID types except for Basic are supported on specific models only.
- "N" represents the total number of hard drives within the volume.
2. Synology Hybrid RAID (SHR)
The Synology Hybrid RAID (SHR) is an automated RAID management system, designed to simplify storage management and meet the needs of new users who are unfamiliar with RAID types. SHR can combine different sized hard drives to create a storage volume with optimized capacity and performance, wasting less hard drive space and providing a more flexible storage solution. When sufficient hard drives are included, SHR allows for 1- or 2-disk redundancy - meaning the SHR Volume can suffer up to one or two failed disks without suffering data loss. To learn more about SHR, please read What is Synology Hybrid RAID?
3. RAID 0
RAID 0 combines two or more disks to increase performance and capacity, but provides no fault tolerance. A single disk failure will result in the loss of all data on the array. RAID 0 is useful for non-critical systems where a high price/performance balance is required.
4. RAID 1
RAID 1 is most often implemented with two hard drives. Data on the hard drives are mirrored, providing fault tolerance in case of hard drive failure. Read performance is increased while write performance will be similar to a single disk. A single disk failure can be sustained without data loss. RAID 1 is often used when fault tolerance is key, and space and performance are not critical requirements.
5. RAID 5
RAID 5 provides fault tolerance and increased read performance – though write performance often suffers. A minimum of three disks is required. RAID 5 can sustain the loss of a single disk. In the event of a disk failure, data from the failed disk is reconstructed from parity striped across the remaining disks. As a result, both read and write performance is severely impacted while a RAID 5 array is in a degraded state. RAID 5 is ideal when space and cost are more important than performance.
6. RAID 6
RAID 6 is very similar to RAID 5, except it provides another layer of striping and can sustain two drive failures. A minimum of four disks is required. The performance of RAID 6 is lower than that of RAID 5 due to this additional fault tolerance. RAID 6 becomes attractive when space and cost are important and sustaining multiple disk failures is required.
10. RAID 10
RAID 10 combines the benefits of RAID 1 and RAID 0. Read and write performance is increased, but only half of the total space is available for data storage. Four or more disks are required making the cost relatively high, but the performance is great while providing fault tolerance at the same time. In fact, a RAID 10 can sustain multiple disk failures – provided the failures are not within the same sub group. RAID 10 is ideal for applications with a high input/output demand such as database servers.
2013-05-08 18:29:42