How to Manage the Synology RAID Volume
From SynologyWiki
| What is RAID and how does it relate to the Synology Disk Station? This article aims to answer those questions, plus more information on what RAID abilities are available on the Synology Disk Station. |  |
Background Information
What is RAID?
RAID in summary, is a technology used by computer systems, which allows for multiple independent hard disks to behave together in concert to provide...
- Fault tolerance against hard drive failure
- To have gain better performance when conducting read/write operations to multiple drives at once, versus one drive
- To create a large data storage device to store vast quantities of data.
When multiple disks are joined together with RAID technology, the end product is known as a RAID Array or RAID Volume. There are a variety of RAID "Levels" which are supported by the Synology Disk Station, to create different types of RAID Volumes. The various RAID Levels will be covered later in this article.
A RAID Volume is no substitute for not having a backup of data; a RAID system is intended to maintain up-time, so data is still available during a disk error. It will not provide protection against viruses, malicious users, or accidental data loss. For further information about the definition of a backup, please refer to the What is a backup article.
What RAID Levels are supported by the Synology Disk Station?
Assuming a Synology Disk Station is operating Synology Disk Station Manager 2.1-0839, the following RAID Levels are supported.
| RAID Type | Disks Supported | Tolerable Disk Failures | Description |
|---|---|---|---|
| Basic | 1 | 0 | Non-RAID |
| JBOD | 2, 3, 4, 5 | 0 | Spanning of data across multiple odd-sized disks |
| RAID-0 | 2, 3, 4, 5 | 0 | Striping of data across multiple disks |
| RAID-1 | 2 | 1 | Mirroring of data across two disks |
| RAID-5 | 3, 4, 5 | 1 | Striping of data with distributed parity |
| RAID-5 + Hot-Spare | 4, 5 | 1 | Striping of data with distributed parity data, and with Hot-Spare Disk |
| RAID-6 | 4, 5 | 2 | Striping of data with dual distributed parity data |
- Tolerable disk failures is defined as how many disks can be lost from the array before total volume failure will occur.
- Any disk error or power failure in a JBOD/RAID-0 Environment may result in the total destruction of the Volume. While it offers the most capacity, it is also most vulnerable to errors and is not advisable to use this Volume type.
- Basic, JBOD, and RAID-0 are considered non-redundant RAID Volume types, while RAID-1, RAID-5, and RAID-6 are considered Redundant Volume Types.
Can the Synology RAID grow with additional storage?
Multi-bay Synology Disk Stations using Redundant RAID Volumes are capable of growing in storage capacity in the following ways
- Vertically
- Where smaller disks are incrementally changed to larger disks, ie 2x500GB Disks in RAID-1 are replaced with 2x2TB Disks, in RAID-1
- Horizontally
- Where additional disks are added to an existing RAID Volume, ie, 2x500GB Disks in RAID-1 is converted into 4x500GB Disks in RAID-5
- Plug-and-Use Expand
- Applicable to the DS509+ with DX5 (or RS409+ with RX4), where the volume from the DS509+ is expanded onto the HDD Volume located on the DX5.
Notes about Volume Growth
Before executing RAID growth
Before executing any type of RAID manipulation, or even using the Synology system, it is recommended to have a backup of data present. While not designed to affect the data volume, it's a strong recommendation for safety’s sakes. For further information about what is a backup, please look here. It is also recommended to disable IPKG temporarily.
Is data still accessible during Volume Growth?
With Synology's Disk Station Manager 2.1, during the Volume Manipulation procedure the data on the system will still be online for use. The system may suspend connections for a few moments to get the process started, but afterwards, the Synology Disk Station will resume the network access, thus, allowing users to continually access their data during the Volume Expansion, or Volume Change.
How to Guides to manage a RAID Volume with the Synology Disk Station
- How to create a RAID Volume on the Synology Disk Station
- Definitions of RAID Status on the Synology Disk Station
- How to repair a Volume with the Synology Disk Station
- How to expand the RAID Volume with larger disks
- How to expand the RAID Volume with additional disks
- How to expand the RAID Volume with Plug-n-Use Expand
