3PAR storage Remote Copy Failover, Recovery & Restore using IMC
Today we have a highly detailed guest post covering the 3PAR remote copy failover and recovery process. If you fancy writing a guest post check out this post.
About the author
Written by Deepak Garg, a technocrat with over 10+ years of experience in storage administration and with technical expertise in managing the technical support functions. Expert on HPE 3PAR, HPE StoreOnce, HP EVA Storage, HP MSA/P2000, LHN and many other HPE products
Unidirectional 1-to-1 Configuration
A unidirectional 1-to-1 remote-copy configuration is composed of one remote-copy pair. Each storage system in the pair plays only one role: one system is the primary system, and one system is the backup system.
Bidirectional 1-to-1 Configuration
A bidirectional 1-to-1 remote-copy configuration is composed of one remote-copy pair.Each storage system in the pair functions as both the primary and backup system and each system contains both primary and secondary volume groups.
Each system provides backup for the other, according to the direction of replication specified for each volume group. Below figure illustrates a bidirectional 1-to-1 remote-copy configuration.
System Information during Failover for 1-to-1 Configurations
Asynchronous Periodic Mode for 1-to-1 Configurations
When a failure occurs on systems with asynchronous periodic mode volume groups such that all links between the systems are broken, the following actions occur:
- After 60 seconds, the system marks the sending links as down.
- After another 200 seconds, the system marks the targets as failed
Recovering from Disaster for 1-to-1 Configurations
For the remote copy failover, recover and restore operation there are defined steps involved which need to followed as below.
a) Stop Remote Copy Group
Reverse the role of all volume groups on the system that is still in normal operation (the failover system). Here we will consider that system “System-A” is in failed state or having some planned maintenance activity. Below screen shot shows where we want to do the failover of replication group “DRTEST” from primary system System-A to System-B
During this first of all we have to stop the remote copy replication group “DRTEST” to do the testing.
From the 3PAR management console, click on remote copy from the left pane. After this click on the groups and verify the replication group listed on the right side as shown below in picture.
We will be doing the failover of “DRTEST” replication group. So right click on “DRTEST” and click Stop Remote Copy Group(s) as shown below in picture:
Once clicked on Stop Remote Copy Group(s) option a pop-up window as shown below will open which will state that remote copy mirroring will be stopped. Click on OK to proceed.
Once we stop Remote Copy Group, replication from source to target will be stopped.
b) Failover Remote Copy Group
Once the remote copy group is in failed state then we will see that Group state is a stopped state. Now we have to right click on the failed remote copy group (in our case we are preparing example with remote copy group “DRTEST”) and click “Failover Remote Copy Group (s)..” option as shown below
Now one pop-up window will open click OK and after that one more pop-up will open and click yes here
Note:- After this failover will be executed for the selected group. The failover operation changes the role of secondary groups on the backup system (i.e. System-B) from “Secondary” to “Primary-Rev”. Any LUNs (VLUNs) associated with the volumes in the selected groups become writable by hosts connected to the backup system (backup system is System-B in our case). These VLUNs will be in writable permission from both side 3PAR so we must ensure that no write operation on VLUN from primary site.
As per picture below, click YES to continue and the failover operation will start.Now there should be Group state as “stopped” as per below picture. Replication status in the table will be as “Stopped” and Backup system (i.e. System-B) will show its role as “Primary-Rev” with DR state as “Failover”.
This completes all failover steps.
a) Description of Recovery Option
Recover option will recover the failed system (in our case failed system is System-A). When both systems in the remote-copy pair are ready to resume normal operation, reverse the natural direction of data flow and resynchronize the systems.
At this time we have to right click on the replication group which was failed earlier (in our case it is “DRTEST”) and click on “Recover Remote Copy Group (s).. This will copy data / initiates reverse replication and synchronize the delta changes from the reversed volume groups on the failover system (System-B) to the corresponding volume groups on the recovered system (System-A).
Once executed the role of the remote copy group on the source system (System-A) becomes “Secondary-Rev”. Also, any LUN associated with the volumes in the selected groups become non-writable on the source system (System-A).
Note: – The recovery operation can be executed only on groups that have successfully completed the failover option.
b) Recover Remote Copy Group
Below two pictures shows the process on how to put a replication group in recover state and then click YES in pop-up window. Right click on the replication group which was failover and click on the option “Recover Remote Copy Group(s)”
Once clicked on OK prompt, there will be one more pop-up, press yes now. Important to note that VLUNs will not be writable now on source system “System-A” and it will be in writable mode on backup system “System-B”.
Now, we should be able to see Source role for “DRTEST” on source system should be “Secondary-Rev” and “Primary-Rev” on the Backup system role as shown in below picture. Now the DR state will be in “Recover” statc) Verification:
1 Issue the showrcopy command from the CLI on the failover system (System-B).Verify the following:
- The Status of the target system (recovered system – “System-A”) is ready
- The SyncStatus of all volumes in the Primary-Rev volume groups is Syncing.
- The Status of all sending links is Up,
2 Issue the showrcopy command from the CLI on the recovered system (System-A) Verify the following:
- The Status of the target system (System-B) is ready
- The Status of all sending links is Up
- The Role of the synchronizing volume groups is Secondary-Rev
- The SyncStatus of all volumes in the Secondary-Rev volume groups is Syncing
Once the recovery is completed for the remote copy group then we must restore back the actual state of replication group. I.e. bring the replication group (in our case it is “DRTEST”) back to “System-A” as primary role and again replication from the primary system (System-A) to backup system (System-B).
b) Procedure to Implement
For doing this right click on the replication group and click “Restore Remote Copy Group(s)..”.This restore operation restores replication for the selected Remote Copy group to a pre-failover state after the recovery operation has been completed. Once the Restore operation is executed the role of the remote copy group on source system (System-A) will be “primary” and the Remote copy group on the backup system will be “Secondary”. Also, any LUNs associated with the volumes in the selected groups become writable by hosts connected to the source system (i.e. System-A) and become non-writable by hosts connected to the backup system (i.e. System-B)
And once we will click on the OK in the above pasted picture, then there will be one more pop-up to click Yes or No, we have to click “Yes” to complete the process.
Now the system should be able to see the status of restored replication group as it was in actual state. Below picture shows the actual status with System-A system as Primary and normal state and replication pointing from System-A to System-B.