You could lose up to ten minutes' worth of writes that happened at the primary site since the last scheduled replication, so your RPO would be 10 minutes. For synchronous replication, you will typically need a really fast network between the two sites. That can be prohibitively expensive, in which case asynchronous replication would be a better solution for you. To begin with, the initial baseline transfer is completed. Then, a snapshot copy of all data on the source volume is created.
This is then transferred to the destination volume. Typically you'll have scheduled updates. You can just run manual ones if you prefer, or you can do a combination of both. When you do an update, a new snapshot copy of the source is taken. The current SnapMirror snapshot copy is compared with the previous SnapMirror snapshot copy, and then only changes are synchronized from the source to the destination incrementally.
Replication is done at the block level, so it's only the changed blocks that get sent across. It's very efficient after the initial baseline transfer. Whenever you do a new replication, only incremental changes at the block level get replicated across. The SnapMirror engine is compatible with storage efficiency and volume moves. Deduplication and compression savings are replicated from the source to the destination volume.
The data is not inflated or decompressed for the transfer. If you've got storage efficiency turned on at the source site, the space savings are going to be automatically replicated to the destination site as well.
This also helps save on your network bandwidth and the amount of time it takes to do the transfer. SnapMirror source or destination volumes can be moved to another aggregate in the cluster without breaking the SnapMirror relationships. If you want to move a volume because your aggregate is getting too full or you want to move it to higher or lower performance disks, you can.
Any SnapMirror relationships will be retained even after you perform the move. Let's now talk about the three different features that use the SnapMirror engine. I'll cover Load Sharing mirrors first. Load Sharing mirrors are mirror copies of FlexVol volumes which provide redundancy and load balancing. They provide load balancing for read traffic only, not for write. Write requests always go to the one source volume so that you have that single, consistent copy of the data. Load Sharing mirror destination volumes are always in the same cluster as the source volume.
This is unlike DP mirrors and SnapVault. Data Protection Mirrors and SnapVault can perform their function either within the same cluster or to a different cluster, whereas Load Sharing mirrors only work within the same cluster. Load Sharing mirrors are automatically mounted into the namespace with the same path as the source volume, and they provide redundancy for read access with no administrator intervention required.
If the source volume goes down, clients can still get read-only access the data without requiring any action from the administrator. Getting write access back if the original source volume cannot be recovered does require the administrator to manually promote one of the mirror copies to be the new source. Next we have Data Protection mirrors DP mirrors. With DP mirrors you can replicate a source volume to a destination volume in the same or in a different cluster.
Most often it'll be a different cluster. They can be used for the following reasons:. As mentioned earlier and unlike Load Sharing mirrors , DP mirror copies are not automatically mounted into the namespace and implicitly accessed by clients.
Step 7. Check the status. Simple example, which will update the snapmirror relationship at 10 a. SnapMirror is a complex technology. In this post I presented only the most simple setup of asynchronus Volume Snapmirror.
If you would like to go a little bit deeper into how the transfer works, how to setup the QSM or what arguments can you specify try this book: Data Protection Online Backup and Recovery Guide. What is SnapMirror? There are three modes availabe: SnapMirror Sync — replicated data to the destination ASAP — so basically when data is written to the source volume it is being replicated instantly.
The wizard will prompt you to choose the source and destination volumes for the new SnapMirror relationship, as well as other options, such as maximum transfer rate, so that you can control the network bandwidth used for synchronization. Finally, the wizard will ask you to review the requested setup and confirm that you wish to proceed. When the SnapMirror relationship has been created, the status of the AWS replication and data transfer can be monitored through the dashboard.
This can be a very cost-effective solution for infrequently accessed systems, such as DR environments. Cloud Central. View All Blogs. Read Next:. More about AWS Snapshots. Subscribe to our blog. Thanks for subscribing to the blog. How do I set it up? Updates the destination to reflect incremental changes on the source, as per the schedule you specify.
Each of the following replication methods consists of a pair of operations, one operation each at the source storage system and the destination storage system: Volume SnapMirror replication Qtree SnapMirror replication SnapVault replication.
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