Synology RS4021xs Synology High Availability SHA User Guide for DSM 7.0
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- Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 1
User Guide for Synology High Availability (SHA) Based on DSM 7.0 and Synology High Availability 2.1.0 1 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 2
Environment 02 2.1 Supported models (as of January 2022) 2.2 System requirements 2.3 Limitations Chapter 3: Set Up and Configure an SHA Cluster 07 3.1 Connect the hosts 3.2 Create a cluster 3.3 Tests and simulations 3.4 Set up storage for SHA 3.5 Monitored services 3.6 Quorum server - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 3
in mind, users can rest assured that their services are constantly maintained, even in the event of sudden disaster. Those who wish to make full use of the support provided by Synology High Availability will benefit from the information in this User Guide. For information regarding SHA design and - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 4
Models section on this page for the latest information on SHA and its supported devices. Series FS series SA series 22 series 21 series 20 series series 17 series 16 series 15 series 14 series 13 series 12 series Supported models FS6400, FS3600, FS3400, FS3017, FS2500, FS2017, FS1018 SA3600, SA3400 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 5
Availability (SHA), the active server and the passive server are referred to as "hosts". Models and versions • To create an SHA cluster, two Synology NAS (hosts) with support for SHA are required to act as the active and passive servers. • We recommend that the models of the two hosts are identical - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 6
same network interface. For example, if one host connects to subnet A via LAN 1, the other host also must connect to subnet A via LAN 1. Note: NTP service will be automatically enabled on the active server once the high-availability cluster is created. 04 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 7
network card. • A Heartbeat connection can transfer Jumbo Frame packets to the other Synology NAS using a specified network interface. If the connection passes through a switch, make sure that the switch also supports Jumbo Frame. • A Heartbeat connection requires low latency, and its response time - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 8
Directory Server prior to cluster creation, refer to the Create a cluster with a Synology NAS in use section for instructions. USB device limitations SHA does not support switchover/failover for USB devices. Any services or applications provided by USB devices may not work properly after switchover - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 9
Chapter 3: Set Up and Configure an SHA Cluster Chapter 3: Set Up and Configure an SHA Cluster 3.1 Connect the hosts To achieve broader bandwidth for the cluster and Heartbeat connections, we recommend you to set up network interfaces as follows: • If you have four 1 GbE network interfaces available, - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 10
and belong to the same network. To avoid service interruptions caused by network disconnection, we recommend you Synology NAS This section provides instructions on how to create a high-availability cluster using two new Synology NAS. For example, we will use two brand-new DS1621+ Synology NAS - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 11
Chapter 3: Set Up and Configure an SHA Cluster • Server B • Server name: NAS-B • LAN 1: DHCP IP address • LAN 2: Static IP address 10.17.196.13 4. On each server, go to the Package Center and install Synology High Availability. 5. Sign in on the host that you want to assume the role of the active - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 12
Chapter 3: Set Up and Configure an SHA Cluster 8. Read the content of the Before you start page carefully. After confirming that the configurations of your two servers meet the requirements, click Next. 9. If the recommended network configuration meets your needs, configure your network according to - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 13
We used the following name and IP address for example: • Cluster Hostname: NAS-HA • Cluster Static IP address: 10.17.196.14 13. The Done. 15. Tick the checkbox after reading the instructions and click Yes. 16. The wizard will start creating services via the new cluster hostname and IP address. 11 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 14
services, but will remain in standby mode. • You can manage the cluster in Synology Synology High Availability does not support Synology NAS implemented with SHR (Synology Hybrid RAID). If you have already set up SHR on your existing Synology NAS to this article for instructions. b. Go to Storage - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 15
instructions. b. Go to the Package Center and uninstall Synology Directory Server. c. Create a high-availability cluster. d. Reinstall Synology Hostname or IP address of the active server to access your Synology NAS. If services are transferred to another server after a failover, the original active - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 16
Configure an SHA Cluster 5. Click Yes to open the cluster creation wizard. Services on the active server will continue during cluster creation. 6. Read the settings and click Done. 11. Tick the checkbox after reading the instructions and click Yes. 12. The wizard will start creating the high- - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 17
the passive server, while the original passive server will take over the provision of services to become the active server. To trigger an auto-failover: On the Cluster step-by-step instructions on how to manually initiate a switchover, trigger an auto-failover, or simulate connection problems. 15 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 18
unplug all cables from the active server (NAS-A). Services will be temporarily unavailable. 3. The system will notice that the active server (NAS-A) is unavailable and perform autofailover to the passive server (NAS-B). The passive server (NAS-B) will become the active server and start providing - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 19
that the data is inconsistent (split-brain error), the High Availability cluster will enter Safe Mode. 7. After waiting some time, sign in to DSM (NAS-A) via one of the server's IP address. You will see that the high-availability cluster status displays Split-brain error. Notes: 1. If you do - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 20
the split-brain error 1. Sign in to DSM (NAS-A) via the cluster IP address. 2. Services on both the servers and the IP addresses of the is complete. 3.4 Set up storage for SHA Before you start This user guide uses the following examples, which are based on SHA's minimum requirements: • - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 21
Chapter 3: Set Up and Configure an SHA Cluster Notes: • Only RAID 1, RAID 5, RAID 6, RAID 10, RAID F1 and BASIC are supported. • Please install a brand new hard disk, as a used hard disk may encounter unexpected issues. • The storage settings will be synchronized on both the active and - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 22
4. Select and deploy the two drives and click Next. Chapter 3: Set Up and Configure an SHA Cluster 5. Select Perform drive check and click Next. 6. Allocate the capacity size and click Next. 7. Select Btrfs for the file system and click Next. For more information on file systems, refer to this - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 23
Chapter 3: Set Up and Configure an SHA Cluster 3.5 Monitored services Select the services that you want to monitor with Synology High Availability. If a monitored service fails on the active server, the system will fail over to the passive server as long as it is operating normally. 3.6 Quorum - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 24
Set Up and Configure an SHA Cluster Set up a quorum server 1. Go to Synology High Availability > Service. 2. Tick Enable quorum server and enter the IP address of the quorum server. on your needs. The following three types of UPS are supported by SHA: • SNMP UPS • USB UPS • Synology UPS server 22 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 25
If something happens to the power supply, UPS will help prevent the Synology NAS from powering off unexpectedly. If the active server experiences issues with its supply, the passive server will enter Safe Mode alone and not affect services on the active server. Once the power issue is resolved, the - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 26
switch and set up any type of UPS (USB UPS / SNMP UPS / Synology UPS server) as the power source protection. If you use USB UPS, connect the occurs, the entire cluster will enter Safe Mode. If you use a SNMP UPS or Synology UPS server, you can connect one or both of the servers to the same UPS. - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 27
UPS or Synology UPS server, you will need to set up a corresponding UPS IP address for each server. In this case, if there is a problem with one of the power supplies, the connected server will enter Safe Mode. If the power supply is that of the active server, services will fail - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 28
on, the passive server will not take over services to avoid a Splitbrain error. 3.9 System notifications If a major event or problem occurs in the system, you may want to be notified as soon as possible. This section provides instructions for notifications settings. Enable email notifications 1. Go - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 29
, add a subject prefix in the Subject prefix field. This prefix will be added to the subject of each message sent by your Synology NAS, helping you identify and filter messages. 5. Refer to the respective help articles for DSM 7.0 and DSM 6.2 for more information. Notification content settings - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 30
Chapter 4: Navigate the SHA User Interface Chapter 4: Navigate the SHA User Interface To learn more about how to navigate the SHA User Interface, you can refer to the respective help articles for DSM 7.0 and DSM 6.2. 4.1 Cluster The Cluster page provides an overview of your SHA cluster. This page is - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 31
case, all services will be suspended to avoid further data inconsistencies until the issues are resolved. To troubleshoot abnormal high availability cluster statuses (Warning or Critical), refer to Chapter 2: SHA Troubleshooting in the Synology High Availability (SHA) Troubleshooting Guide. High - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 32
usage of the hosts are correlated, however, the statistics of the active server are usually be higher since it is responsible for running all services. In this section, you can check the following: • CPU utilization and load average: To ensure that the system reserves sufficient resources to monitor - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 33
, refer to the Log tab. 4.2 Host The Host page displays crucial information about the two hosts. This includes the Find button - for locating your NAS via a beeping sound and LED light - and the Power buttons for each server. This page also shows each host's information, along with their hardware - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 34
Chapter 4: Navigate the SHA User Interface 4.3 Network This page contains two tabs, one that provides the network settings of the high-availability cluster and the other of the hosts. You can get an overview of the network interface usage and create or remove additional Cluster connections if - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 35
Hosts This tab shows the statuses and details of the network interfaces on the active and the passive servers. 4.4 Service This page allows you to monitor certain services. If a monitored service fails on the active server, the system will fail over to the passive server as long as the passive - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 36
Supported services • Windows File Service • iSCSI Target • FTP • Mac File Service • NFS Service • Synology Directory Server • Web Services Refer Set Up and Configure an SHA Cluster for more information and setup instructions. 4.5 Storage This page details the statuses of the storage volumes on - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 37
Chapter 4: Navigate the SHA User Interface The following situations may require you to repair a malfunctioning volume or iSCSI LUN: • If a volume on one of the servers has crashed • If the passive server is offline • If a file system error occurs You can use the Repair button in the case that you - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 38
to either of the servers with the cluster IP address and open Synology High Availability. 3. To view the differences in the data on the data, follow the instructions in this article. 4. Click Manage > Resolve split-brain errors on the Cluster page and follow the onscreen instructions. There are two - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 39
(original active server). Services will remain uninterrupted on the NAS will check if there is a new version available. If there is a new version available, click Download and then click Update Now to begin the update process.2 To update DSM manually on a high-availability cluster: 1. Go to Synology - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 40
using two different Synology NAS models to create a hybrid high-availability cluster, you can only update DSM manually. 1. Go to Synology Download Center, Synology High Availability package Services will still be available while updating the Synology High Availability package. 1. Go to Synology High - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 41
via DSM. Firmware updates ensure the compatibility and continued use of the Synology drives installed in your Synology NAS. If the firmware status of one order to halt all services during the update and prevent any application errors. • You can perform firmware updates for Synology drives on both - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 42
, and disable2 the SHA cluster IP address, or click Configure Server Network to edit the IP addresses of the active and passive servers. 3. Select Use manual configuration and edit the network information of either or both servers. 4. Click OK when you're done. 40 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 43
to configure the new network settings. 6. Enter a DSM administrator's username and password. 7. Select Use manual configuration and specify the new IP information. 8. Click OK to save your settings. 9. Go to Synology Assistant again, and you will see that your cluster's IP address has changed. 10 - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 44
are listed on the Synology Products Compatibility List. Using incompatible healthy. 5. Make sure your Synology NAS model supports using drives located in expansion units Synology NAS, make sure to follow the drive installation instructions found in the Hardware Installation Guide for your Synology - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 45
active server and replace it with one of a larger size. To avoid injury or damaging your Synology NAS, make sure to follow the drive installation instructions found in the Hardware Installation Guide for your Synology device.1 3. Go to Storage Manager > HDD/SSD to make sure the newly added drive has - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 46
Notes: 1. Your device's Hardware Installation Guide can be found in the Synology Download Center under Documents. 2. When NAS in a high-availability cluster, you will be able to expand its storage capacity with expansion units. Refer to this article to see if your servers are compatible with Synology - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 47
of the two servers is exactly the same to ensure that services can be properly transferred and to maintain consistent system performance. • Go to the Download Center and download the Hardware Installation Guide for your Synology NAS. Method 1: Shut down the cluster You can expand the memory - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 48
return to normal. For more details, refer to Chapter 2: SHA Troubleshooting in the Synology High Availability (SHA) Troubleshooting Guide. 5.6 M.2 SSD installation SSD caches can achieve better performance on Synology NAS by leveraging the advantages of SSDs. By storing frequently accessed data in - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 49
and download the Hardware Installation Guide and Datasheet for your Synology NAS. Then, check the following: • Make sure that the PCIe slot is supported on your Synology NAS. • Confirm that the network interface card you want to use is listed on Synology Products Compatibility List. • Make sure that - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 50
function. 1. Sign in to your high-availability cluster and go to Synology High Availability > Host. 2. On the passive server, click the power button and select Shut Down. 3. Refer to the Hardware Installation Guide for instructions on how to install the network interface card on the passive - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 51
to Synology Synology NAS. 3. Install the drives on the destination Synology NAS Synology NAS. 5. Power on the destination Synology NAS (new passive server). 6. Open a web browser on your computer and go to find.synology.com. 7. Find the destination Synology NAS the destination Synology NAS will - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 52
on the source Synology NAS. 11. Once the migration is complete, the destination Synology NAS will automatically be instructions. Note: If the cluster is in an abnormal state before migration, refer to Chapter 2: SHA Troubleshooting in the Synology High Availability (SHA) Troubleshooting Guide - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 53
Learn more Learn more Related articles • Can I create a high-availability cluster with two different Synology NAS servers? • What should I know when creating a Heartbeat connection for a Synology High Availability cluster? • How long does it take to synchronize high-availability clusters? • What is - Synology RS4021xs | Synology High Availability SHA User Guide for DSM 7.0 - Page 54
specifications and product descriptions at any time, without notice. Copyright © 2022 Synology Inc. All rights reserved. ® Synology and other names of Synology Products are proprietary marks or registered trademarks of Synology Inc. Other products and company names mentioned herein are trademarks of
User Guide for
Synology High Availability (SHA)
Based on
DSM 7.0 and Synology High Availability 2.1.0