Planning for disks in your Synology Product
From SynologyWiki
| This article will cover basic information and planning for storage capacity for the Synology Multi-bay models. |
Disk Configurations
The Synology Product use a technology of RAID to allow for greater hardware redundancy and disk capacity by merging multiple disks to work together. Currently, a Synology multi-bay product with Disk Station Manager 2.0-0598 supports the following RAID Types
| RAID Type | Disks Supported | Tolerable Disk Failures |
|---|---|---|
| Non-RAID | 1 | 0 |
| RAID 0 | 2, 3, 4, 5 | 0 |
| RAID 1 | 2 | 1 |
| RAID 5 | 3, 4, 5 | 1 |
- Tolerable disk failures is defined as how many disks can be lost from the array before total data lost will occur.
- Any disk error or power failure in a 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.
Capacity Examples
Assuming a Synology DS508 is populated with 1TB HDDs, here is a table of the possible storage capacity available to the administrator. For simplicity, this table will only cover the maximum supported disks for each RAID type.
| RAID Type | Number of Disks Used | Capacity (TB) |
|---|---|---|
| Non-RAID | 1 | 1 |
| RAID 0 | 5 | 5 |
| RAID 1 | 2 | 1 |
| RAID 5 | 5 | 4 |
Note: With all capacity estimates are displayed in Decimal Capacity, such as 4TB. This does not mean that a user has 4TB of storage, however, the user has a raw estimated 3.7TiB of available or usable storage. Note the difference capacity designation, as it is being displayed as a Binary Terabyte. For further information about the differences between Decimal Capacity and Binary Capacity, please refer to this article.
Upgrading Volume Types
Security Precaution
Before executing any type of RAID manipulation, or even using the Synology system, it is recommended to have a backup of data present. For further information about what is a backup, please look here.
Converting Non-RAID to RAID 1 Volume
The Synology System currently supports converting a Non-RAID Volume into a RAID-1 Volume. To briefly cover the procedure, if another disk is available in a Synology system, the Disk Station Manager will prompt the Administrator that the current Non-RAID Volume can be upgraded to the redundant Volume RAID-1. Use the Disk Station Manager to begin the upgrade. This should not destroy the data volume, but it is always recommended to have a backup of the as a security precaution.
Converting Non-RAID/RAID 0/RAID 1 into a RAID 5 Volume
Currently, the Synology System does not support the ability of converting a Non-RAID/RAID 0/RAID 1 Volume into a RAID 5 Volume. It is most likely to be unsupported by Synology as to do so would involve using proprietary RAID technology, which cannot be used in another system, such as a Linux Computer.
To convert from a Non-RAID/RAID 0/RAID 1 Volume, the entire volume will have to be deleted and then rebuilt as the RAID 5 type. Please ensure that a backup copy of the data exists before deleting the volume, as deleting a volume will result in data destruction.
Expanding RAID 1/RAID 5 Disk capacity
Currently, the Synology system supports Redundant RAID Array disk-level expansion, where smaller disks can replaced with a larger disk. This allows users to convert for example...
Convert 2-drive xxxGB RAID 1 into 2-drive yyyGB RAID 1
Convert f-drive xxxGB RAID 5 into f-drive yyyGB RAID 5 (where f = 3, 4, or 5)
This allows users to continually expand the storage capacity of their Synology system, as their storage needs grow larger.
RAID 5 Volume Reshaping
With the introduction of the Synology Disk Station Manager 2.0-0598, Synology introduce the ability of "Adding a disk" to an existing RAID 5 Volume to expand the current capacity. This will allow users to expand a 3-disk RAID 5 Array to a 4-disk RAID-5 Array for example. However, during the Volume Reshaping process, there will be no parity protection to the Volume, thus any disk error or power failure may result in the destruction of the Volume. However, after the Reshaping process has completed, the parity protection will be restored, where the RAID-5 Volume can tolerate the loss of one disk.
Criticisms of Volume Manipulation
When performing a Volume Manipulation (converting from RAID 1 to RAID 5, moving from 3-disk RAID 5 to 4-disk RAID 5 to 5-disk RAID 5 for example), the most costly resource is time. To avoid this cost of time, it is recommended to build any RAID array completely full of disks, and not start out with one or two HDD units. Though the option of starting out with a small amount of disks is available for those administrators who wish to save resources in the immediate term; however it may not save resources when the a RAID systems needs more capacity when it is being used as a "live system" in the future.
