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How to create and manage RAID volumes on the DiskStation

Overview

This document is to guide you through how to create and manage the RAID volume of your DiskStation.

Contents

  1. What is RAID?
  2. What is Synology Hybrid RAID(SHR)?
  3. Create a Volume on Synology DiskStation
  4. Expand an Existing RAID Volume
  5. Change the Volume Type
  6. Repair a Volume
  7. Remove a Volume
  8. Appendix: Volume Types Supported by Synology DiskStation

1. What is RAID?

RAID (Redundant Array of Independent Disks), in summary, is a technology that combines multiple independent hard disks to work as a unit. By various RAID types, this technology provides the benefits such as increasing data reliability, improving input/output performance, raising failure tolerance, etc.

When multiple disks are joined together with RAID technology, it is called RAID Array or RAID Volume. Please note that a RAID Volume is not a substitute of data backup, nor does it provide protection against viruses, malicious users, or accidental data loss.

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2. What is Synology Hybrid RAID(SHR)?

There are a variety of RAID "Levels" supported by the Synology DiskStation to create different types of RAID Volumes1. You can easily create a RAID volume on your DiskStation by DiskStation Manager.

But if you are not sure which RAID type to go for, or simply wish to have DSM arrange everything for you, Synology Hybrid RAID (SHR) will be the solution. It not only simplifies the volume creation process, but also offers a flexibility of capacity that traditional RAID technology can’t. For example:

If you want to create a volume using 3 hard disks of size 160GB, 300GB, and 500GB respectively, traditional RAID technology offers a RAID 5 volume with 320GB storage space:

However, under the same scenario, SHR will identify that another RAID 1 volume can be created and offer you another 140GB storage capacity.

When you add another hard disk into the existing volume, SHR will adjust the volume size to the optimized status. Thus, the RAID 1 volume that was created in the previous image will be transformed to RAID 5 to offer bigger storage capacity. SHR offers a 960GB space as shown below, while the traditional RAID technology only offers half the size.

SHR provides one-disk data protection and the flexibility of expanding to an optimal volume space when a larger or additional hard disk is added.

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3. Create a Volume on Synology DiskStation

On Synology DiskStation, you can create volumes in 2 different modes: Synology Hybrid RAID (SHR) Mode > or Custom Mode. The steps are shown below.

  1. To create a RAID volume, go to Main Menu > Storage Manager > Storage page.
  2. Click on Create and follow the guide of Volume Creation Wizard to create the volume.
  3. Select the mode in which you’d like to create a volume. Click Next to continue.

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3.1 SHR Mode

By selecting SHR Mode, Synology DiskStation will help you create an optimized storage allocation based on the number of installed disks. SHR volumes consisting of two or three hard disks provide 1-disk fault tolerance, while SHR volumes consisting of four or more hard disks can provide 1- or 2-disk fault tolerance. Follow the steps below to continue:

  1. After choosing to create a volume in SHR mode, select hard disks with which you want to create a volume by ticking the checkboxes before them. The system will create a volume of optimized capacity based on the hard disks you have selected.
  2. Make sure there is no important data on the selected hard disks. All data on them will be erased during the process. Click Yes to go back to the Volume Creation Wizard page and then click Next to continue.
  3. Select Yes if you want to perform disk check. By performing disk check, bad sectors will be automatically remapped if found. Performing disk check takes some time, but errors are less likely to occur during the volume building process. Click Next to continue.
  4. When you have completed the process above, you’ll be taken to the confirmation page. Check out the information listed here.

    5. Proceed by clicking Apply and your DiskStation will start creating the volume.

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3.2 Custom Mode

By selecting Custom Mode, you can create a RAID or non-RAID volume. Follow the steps below:

  1. After choosing to create a volume in custom mode, select Volume to create a volume. Click Next to continue.
  2. Select the hard disks with which you want to create a volume by ticking the checkboxes before them. Click Next to continue.
  3. Make sure there is no important data on the selected hard disk. All data on them will be erased during the process. Click Yes to go back to the Volume Creation Wizard page and then click Next to continue.
  4. Select the volume type that you’d like to use. Click Next to continue.
  5. Select if disk check should be performed. By performing disk check, bad sectors will be automatically remapped if found. Performing disk check takes some time, but errors are less likely to occur during the volume building process. Click Next to continue.
  6. When you have completed the process above, you will be taken to the confirmation page. Check the information listed here. You can return and modify the settings by clicking Back. Proceed by clicking Apply and your DiskStation will start creating the volume.

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4. Expand an Existing RAID Volume

Multi-bay Synology DiskStations using Redundant RAID Volumes are capable of expanding storage capacity in the following ways:

  • Vertically： Where smaller disks are incrementally changed to larger disks, like 2 x 500 GB disks in RAID 1 are replaced with 2 x 2 TB disks, for example.
  • Horizontally：Where additional disks are added to an existing RAID Volume, like 2 x 500 GB disks in RAID 1 are converted into 4 x 500 GB disks in RAID 5, for example.
  • Plug-and-Use Expand：Applicable to DiskStations with expansion units, where the volume from the DiskStation is expanded with the HDD Volume located on the expansion unit.

Before executing volume expansion
Before executing any type of RAID expansion, it is recommended to backup present data. Though DiskStation is designed not to affect the data when expanding volume, we strongly recommend you to backup your data before executing volume expansion to avoid any risk. It is also recommended to disable IPKG temporarily.

Is data still accessible during volume expansion?
With Synology's DiskStation Manager, the data on the system will still be online for use during the volume manipulation procedure. The system may suspend connection to get the process started, but Synology DiskStation will resume the network access and allow users to access their data during the volume expansion or volume change in a few moments.


Note：For cold-swap models, the data will be off-line during the disk replacement procedure.

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4.1 Expand the RAID Volume by Replacing Existing Hard Disks

Volume expansion differs according to the number of bays the DiskStation has and its RAID type. This section will guide you to expand the RAID volume by replacing a hard disk with a bigger one without losing your data.

Before you begin, please check the following:

  • The status of your RAID volume is Normal.
  • The size of the new hard disk is larger than the size of the disk replaced.
  • If your DiskStation does not support hot-swap, please turn it off before adding new hard disks. For models support hot-swap, you can perform the volume expansion procedure with the power on.

For one-bay models:

  1. Turn off the DiskStation.
  2. Replace the hard disk with one of larger size.
  3. Turn on the DiskStation.
  4. Reinstall the DSM.
  5. Connect the replaced hard disk to the USB or eSATA port of your DiskStation.
  6. Go to Main Menu > File Browser. You will see a “usbshare” or “satashare” folder in it. The data of the old hard disk is inside. Copy the data from the folder to the new hard disk.
  7. After copying the data, you can remove the old hard disk. The volume capacity is now successfully expanded.

For Basic or RAID 0 volumes types:

  1. Back up all data stored on the DiskStation to another storage target. If using external storage device, go to Main Menu > File Browser page, you will see either a "usbshare" folder or a "satashare" folder, depending on the way of connection between your storage target and DiskStation. You can backup all your data into the folder.
  2. Turn off the DiskStation.
  3. Replace "all" the hard disks on the DiskStation with ones of larger size.
  4. Turn on the DiskStation.
  5. Reinstall the DSM and create a new volume.
  6. Copy the backup data to the new volume.
  7. The volume capacity is now successfully expanded with all the old data inside.

For RAID1, RAID5 and RAID6 volume types:
These volume types have failure tolerance ability, which means you can expand storage capacity by replacing old disk(s) with new one(s). When expanding capacity of RAID volumes, you have to replace hard disks "one by one". After each replacement, you have to initialize the new hard disk by going through the “Repair” procedure (step 1 to 5). Then you can continue with the next hard disk. When all the new hard disks are replaced and repaired, the DiskStation will expand the volume automatically.
Please follow the instructions below:

  1. Replace one disk with another of larger size.
  2. Login to the DiskStation by admin account.
  3. Go to Main Menu > Storage Manager > Storage page. Select the volume you want to expand the volume. It should be marked as Degraded now on the UI.
  4. Click Manage. The Volume Manager Wizard shows.
  5. Select Repair and follow the wizard to continue.
  6. After the repair process is done with the new hard disk and the volume status is back to Normal, proceed to replace another disk. Repeat the process (step 1 to 5) until you are done with all the new disks.
  7. When all the new hard disks are replaced and repaired, the DiskStation will expand the volume automatically.
Note :
  • Before replacing the spare disk of a “RAID 5+Spare” volume, you have to change the RAID type first. To do so, click Manage > Change RAID type, and then follow the wizard to change the RAID type of the volume.
  • When the system is removing a volume, all services will be temporarily stopped. When the volume is removed successfully, those services will be started again.

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4.2 Expand a Volume by Adding Additional Hard Disks

The benefit of expanding a volume by adding additional hard disk is that it allows administrator of the DiskStation to start out with one disk, and allow the storage capacity to grow as needed. This function is applicable to the following volume types:

  • SHR RAID
  • JBOD
  • RAID 5
  • RAID 5+Spare
  • RAID 6
If your volume is created in SHR Mode:

Before you begin, please check the followings:

  • The status of your RAID volume is Normal.
  • If your DiskStation does not support hot-swap, please turn it off before adding new hard disks.
  • The size of the hard disk you wish to add must be equal to or larger than the largest disk in the volume. For example, if a volume consists of three hard disks, with respective capacities of 2 TB, 1.5 TB, and 1 TB, then the size of the new hard disk must be 2 TB or above.

Follow the instructions below:

  1. Replace one disk with another of larger size.
  2. Login to the DiskStation by admin account.
  3. Go to Main Menu > Storage Manager > Storage.
  4. Select the volume you want to manage. Click Manage.
  5. Choose Expand the volume by adding hard disks. Click Next.
  6. Select hard disks by ticking the checkboxes. Click Next to continue.
  7. Make sure there is no important data on the selected hard disks. All data on them will be erased during the process. Click Yes to continue.
  8. When you have completed the process above, you’ll be taken to the confirmation page. Check the information listed here. Click Apply to confirm and finish the process. You can return and modify the settings by clicking Back.

If your volume is created in Custom Mode :

Before you begin, please check the following ：
  • The status of your RAID volume is Normal.
  • If your DiskStation does not support hot-swap, please turn it off before adding new hard disks.
  • For "RAID 5", "RAID 5+Spare", and "RAID 6" volume, the hard disk size must be larger than the smallest size of disk in the volume.

Follow the instructions below:

  1. Insert the new hard disk into DiskStation.
  2. Login to the DiskStation by admin account.
  3. Go to Maine Menu > Storage Manager > Storage.
  4. Select the volume you want to manage. Click Manage.
  5. Click Next.
  6. Choose Expand the volume by adding hard disks. Click Next to continue.
  7. Select hard disks by ticking the checkboxes. Click Next to continue.
  8. Make sure there is no important data on the selected hard disks. All data on the selected disks will be erased during the process. Click Yes to continue.
  9. When you have completed the process above, you’ll be taken to the confirmation page. Check the information listed here. Click Apply to confirm and finish the process. You can return and modify the settings by clicking Back.

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5. Change the Volume Type

You can change the volume type according to the total number of hard disks you have. Please see Appendix for detailed info on each volume type.

You can change the volume type as the following:

  • Basic to RAID 1, RAID 5, or RAID 5+Spare
  • RAID 1 to RAID 5 or RAID 5+Spare
  • RAID 5 to RAID 5+Spare or RAID 6

Before you begin, please check the following:

  • The status of your RAID volume is Normal.
  • The size for the replacement hard disk must be larger than the smallest size of disk in the volume.

Follow the instruction below:

  1. Login to the DiskStation by admin account.
  2. Go to Main Menu > Storage Manager > Storage.
  3. Select the volume you want to manage. Click Manage and the Volume Manager Wizard shows.
  4. Select Change RAID type. Click Next to continue.
  5. Select the RAID type that you want to switch to. Click Next to continue.
  6. If the change requires adding additional hard disks to the existing volume, select hard disks by ticking the checkboxes. Click Next to continue.
  7. Make sure there is no important data on the selected hard disks. All data on the selected disks will be erased during the process. Click Yes to continue.
  8. When you have completed the process above, you’ll be taken to the confirmation page. Check the information listed here. Click Apply to confirm and finish the process. You can return and modify the settings by clicking Back.

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6. Repair a Volume

The Repair function is available for “RAID 1”, “RAID 5”, “RAID 5+Spare”, “RAID 6” and “RAID 10” volume types. When the volume status is marked as Degraded, you can repair the volume by replacing the crashed hard disks to keep the data on the volume consistent.

To repair the volume, follow the steps below:

  1. Remove the crashed hard disk as indicated on the page of Storage and replace it with a new one.
  2. Login to the DiskStation by admin account.
  3. Go to Main Menu > Storage Manager > Storage.
  4. Select the volume you want to repair. It should be marked as Degraded on the UI. Click Manage and the Volume Manager Wizard shows.
  5. Select Repair. Click Next to continue.
  6. Make sure there is no important data on the selected hard disks. All data on the selected disks will be erased during the process. Click Yes to continue.
  7. When you have completed the process above, you’ll be taken to the confirmation page. Check the information listed here. Click Apply to confirm and finish the process. You can return and modify the settings by clicking Back.

    8. Warning：If the volume status is marked as Crashed, please Do NOT touch or change anything on the DiskStation and please submit a Support Form on the official website of Synology Inc.

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7. Remove a Volume

All data on the volume will be deleted when you remove it. To remove a volume, follow the steps below:

  1. Login to the DiskStation by admin account.
  2. Go to Main Menu > Storage Manager > Storage.
  3. Select the volume you want to remove. Click Remove button.
  4. Click OK to remove the volume.
  5. Make sure there is no important data on the selected hard disks. All data on the selected disks will be erased during the process. Click Yes to continue.
  6. When you have completed the process above, you’ll be taken to the confirmation page. Check the information listed here. Click Apply to confirm and finish the process. You can return and modify the settings by clicking Back.

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8. Appendix: Volume Types Supported by Synology DiskStation

Volume Type Tolerable Disk Failures HDD Description Volume Capacity
Basic 0 1 A Basic volume must be created with one hard drive as an independent unit. When creating a Basic volume, you can select only one hard drive at a time. 1 x (HDD size)
JBOD2 0 ≧2 JBOD is a collection of hard drives. Sum of all HDD sizes
RAID 0 0 ≧2 Combining multiple disks to build a volume, RAID 0 offers Striping, a process of dividing data into blocks and spreading the data blocks across several hard drives, but without safety measures. N3 x (Smallest HDD size)
Standard 1 ≧1 The Standard volume (also known as Synology Hybrid RAID) can optimize the volume size when combining hard drives with different sizes. If the volume is composed of two or more hard drives, data integrity is protected when one of the hard drives fails. Optimized by the system
RAID 1 1 2 - 4 The system will write identical data to each hard drive at the same time, so data integrity is protected when at least one disk is normal. Smallest HDD size
RAID 5 1 ≧3 This configuration includes a backup option. It uses parity mode to store redundant data on space equal to the size of one disk for later data recovery. (N – 1) x (Smallest HDD size)
RAID 5
+Spare		 1 ≧4 A RAID 5+Spare volume requires at least four drives, and one will act as a hot spare drive to rebuild the failed drive of the volume automatically. (N – 2) x (Smallest HDD size)
RAID 6 2 ≧4 This volume type eliminates the risk of volume failure and provides extra data protection. It uses parity mode to store redundant data on space equal to the size of two disks for later data recovery. (N – 2) x (Smallest HDD size)
RAID10 Half of the total HDD ≧4
(even number)		 RAID 10 has the performance of RAID 0 and data protection level of RAID 1. RAID 10 combines two hard drives into a group, in which data integrity is protected when one of the two hard drives fails. (N / 2) x (Smallest HDD size)

  • Tolerable disk failure is defined as how many disks can be lost from the array but data in the volume is still protected.
  • 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, RAID 5+Spare, RAID 6, and RAID 10 are considered Redundant Volume Types.

___
1. Please refer to Appendix of this document for RAID levels supported by Synology DiskStation.
2. Volume types except for Basic are supported on specific models only. For more information, please visit www.synology.com
3. "N" represents the total number of hard drives within the volume.

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2012-11-08 09:44:34

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Hard DriveInstallationStorage Management

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