Disk Group
You can combine several hard disks to build a Disk Group and create volumes or iSCSI LUNs on it. If the space of the Disk Group is available, you can expand the size of the volumes/ iSCSI LUNs on it according to your needs. Data protection in different levels may be provided according to the RAID type you choose when creating the Disk Group. For RAID types supported by Synology RackStation, please refer to General.
To create a Disk Group:
- Click the Create button.
- Choose a creation mode.
- Quick: This is the easiest way for general users to create a Disk Group. The system will create a SHR RAID type of Disk Group for you to get the optimal balance of space and performance.
- Custom: This is for advanced users who want to choose their own RAID type when creating a Disk Group.
- Follow the wizard to complete the process.
Note:
If you want to create a Disk Group with a certain hard disk but it doesn't appear in the Disk Group Creation Wizard, please check the status of the hard disk in HDD Management.
To remove a Disk Group:
- Select the Disk Group you want to remove.
- Click the Remove button and follow the wizard to complete the process.
Note:
Volumes and iSCSI LUN on the Disk Group will be deleted when you remove the Disk Group. Be careful when using this option.
To repair a Disk Group:
When a Disk Group is in Degraded status and the Suggestion field shows the link of Repair the system partition in blue, you can repair the Disk Group simply by clicking the link, and the Disk Group status will be back to normal.
When the Disk Group is in Degraded status but it is not due to system partition failure, you can repair it when the RAID type is one of the followings: SHR, RAID 1, RAID 5, RAID 5+Spare, RAID 6 and RAID 10. The data on the Disk Group will be consistent after repairing.
- Turn off your RackStation. You can skip this step if your model supports hot-swapping.
- Remove the failing hard disk as indicated in Disk Info of the page and replace it with a new one.
- Click Manage.
- Select Repair.
- Follow the wizard to complete the process.
Note:
- The size of the hard disk for replacement must be larger or equal to the size of the smallest disk in the Disk Group.
- The status of the hard disk for replacement must be "Initialized" or "Not Initialized".
Changing the RAID Type of Disk Groups
You can change the RAID type of a Disk Group if there are available hard disks on your RackStation. Currently, the following types of RAID change are supported:
- Basic to RAID 1, RAID 5 or RAID 5+Spare
- RAID 1 to RAID 5 or RAID 5+Spare
- Add mirror disk to RAID 1
- RAID 5 to RAID 5+Spare or RAID 6
- RAID 5+Spare to RAID 6
Please follow the steps below to change the RAID type of your Disk Group:
- Select the Disk Group you want to change.
- Click Manage.
- Select Change RAID type.
- Follow the wizard to complete the process.
Note:
- You can only change the RAID type of a Disk Group when it is in Normal status; otherwise it will cause data loss. If the Disk Group is in Degraded status, please repair it first.
- If you want to change the RAID type of a Disk Group, enough number of hard disks for the new RAID type is required. The size of the selected hard disk must be larger than the smallest disk in the Disk Group.
- The status of the selected hard disk must be "Initialized" or "Not Initialized".
Expanding the Size of Disk Groups
You can expand the size of a Disk Group by replacing existing hard disks with ones of larger size or by adding hard disks.
Note:
- To expand a volume or Disk Group with 3 TB or larger disks, make sure your volume or Disk Group was created using DSM 3.0 or later.
Expanding Disks Group by Replacing Existing Disks
You can expand a Disk Group by replacing existing hard disks with ones of larger size in the following RAID types: RAID 1, RAID 5, RAID 5+Spare, and RAID 6.
RAID 5 and RAID 6
When replacing hard disks of RAID 5 or RAID 6 volumes or Disk Groups, the smallest hard disk should always be replaced first. The storage capacity of RAID 5 volumes is (number of hard disks – 1) x (smallest hard disk size), and RAID 6 is (number of hard disks – 2) x (smallest hard disk size). Therefore, the smallest hard disk should always be replaced first in order to maximize hard disk usage.
For example, if your RAID 5 volume contains three hard disks that are 4 TB, 3 TB, and 2 TB respectively, the available capacity of your volume will be 4 TB. If you replace the 4 TB or 3 TB disks, the capacity of the volume will not change. To increase the capacity of your volume, the 2 TB hard disk must be replaced first.
To replace disks:
- Turn off your RackStation. You can skip this step if your model supports hot-swapping.
- Replace one hard disk with another of larger size.
- Turn on the RackStation and repair the Disk Group.
- Repeat step 1 to 3 until all hard disks are replaced with ones of larger size.
- The system will expand the Disk Group automatically.
Note:
- When replacing the spare disk of a RAID 5+Spare Disk Group, the RAID type will be changed to RAID 5. After replacing the spare disk of a RAID 5+Spare Disk Group, you need to click Manage and choose Change RAID type to change the RAID type back to RAID 5+Spare and choose the new spare disk as the larger one. Then you can expand the RAID 5+Spare Disk Group.
- All services of Storage Manager will be temporarily stopped during the expansion process.
- You can only expand the hard disk when the Disk Group is in Normal status; otherwise it will cause data loss. If the Disk Group is in Degraded status, please repair it first.
Expanding Disk Groups by Adding Disks
For JBOD, RAID 5, RAID 5+Spare, and RAID 6, the storage capacity of Disk Groups can be expanded by adding more hard disks if there are empty hard drive bays in your RackStation.
Minimum Hard Disk Size
Please see the guidelines below regarding the minimum size of new hard disks.
- For RAID 5, RAID 5+Spare, or RAID 6: The capacity of the hard disk you wish to add must be equal to or larger than the smallest hard disk in the volume or Disk Group. For example, if your volume is composed of three hard disks – 2 TB, 1.5 TB, and 1 TB respectively – then the capacity of the new hard disk must be at least 1 TB.
To add more hard disks:
- Select the Disk Group you want to expand.
- Click Manage.
- Select the hard disks with which you want to expand the size of RAID.
- Follow the wizard to complete setup.
Note:
- The Disk Group status must be Normal.
- For RAID 5, RAID 5+Spare and RAID 6 types of Disk Group, the hard disk size must be larger than the smallest disk in the Disk Group.
- The status of the selected hard disk must be "Initialized" or "Not Initialized".
Data Scrubbing
Data scrubbing is a data maintenance function that inspects volumes or Disk Groups and repairs any detected data inconsistencies. This function can be used with volumes or Disk Groups that implement SHR (comprised of three or more disks), RAID 5, or RAID 6.
We recommend regularly performing data scrubbing in order to maintain data consistency and avoid losing any critical data in the event of disk failure.
To perform data scrubbing:
- Select the volume or Disk Group on which to perform data scrubbing.
- Click Manage
- Select Data scrubbing.
Note:
- Data scrubbing can only be performed when the status of the volume or Disk Group is Normal.
- Please do not shut down the system before data scrubbing is completed. If the system is shut down before completion, data scrubbing must be restarted from the beginning.