Nutanix refers to its current implementation of redirect-on-write snapshots as vDisk based snapshots. Nutanix has continued to improve on its implementation of snapshots by adding in Light-Weight Snapshots (LWS) to provide near-sync replication. LWS uses markers instead of creating full snapshots for RPO 15 minutes and under. LWS further reduce overhead with managing metadata and remove overhead associated high number of frequent caused by long snapshot chains. The administrator doesn’t have to worry about setting a policy between using vDisk snapshots or LWS. Acropolis Operating System (AOS) will transition between the two forms of replication based on the RPO and available bandwidth. If the network can’t handle the low RPO replication will transition out of near-sync. When the network is OK again to meet the near-sync requirements AOS will start using LWS again. In over-subscribed networks, near-sync can provide almost the same level protection a synchronous replication without impacting the running workload.

The administrator only need to set the RPO, no knowledge of near-sync is needed.

The tradeoff is that all changes are handled in SSD when near-sync is enabled. Due to this trade off Nutanix reserves a percentage of SSD space to be used by LWS when it’s enabled.

In the above diagram, first a vDisk based snapshot is taken and replicated to the remote site. Once the fully replication is complete, LWS will begin at the set schedule. If there is no remote site setup LWS will happen locally right way. If you have the bandwidth available life is good but that’s not always the case in the real world. If you miss your RPO target repeatedly it will automatically transition back to vDisk based snapshots. Once vDisk based snapshots meets occurs fast enough it will automatically transition back to near-sync. Both transitioning out and into near-sync is controlled by advanced settings called gflags.
One the destination side AOS creates hydration points. Hydration points is a way for the LWS to transition into a vDisk based snapshot. The process for inline hydration is to:

1. Create a staging area for each VM (CG) that’s protected by the production domain
2. The staging area is essentially a directory with a set of vdisks for the VM.
3. Afterwards, any new incoming LWS’s will be applied to the same set of vdisks.
4. And the staging area can be snapshotted from time to time and then you would have individual vdisk-backed snapshots.

The source side doesn’t need to hydrate as a vDisk based snapshot is taken every hour.

Have questions? Please leave a comment.

The Nutanix platform’s self-healing design reduces operational and support costs, such as unnecessary site visits and overtime. With Nutanix, you can proactively schedule projects and site visits on a regular cadence, rather than working around emergencies. Prism, our end-to-end infrastructure management tool, streamlines remote cluster operations via one-click upgrades, while also providing simple orchestration for multiple cluster upgrades. Following the best practices in this new document ensures that your business services are quickly restored in the event of a disaster. The Nutanix Enterprise Cloud Platform makes deploying and operating remote and branch offices as easy as deploying to the public cloud, but with control and security on your own terms.

One section I would like to call out in the doc is how to seed your customer data if your dealing with poor WAN links.

Seed Procedure

The following procedure lets you use seed cluster (SC) storage capacity to bypass the network replication step. In the course of this procedure, the administrator stores a snapshot of the VMs on the SC while it’s installed in the ROBO site, then physically ships it to the main datacenter.

Install and configure application VMs on a ROBO cluster.
Create a protection domain (PD) called PD1 on the ROBO cluster for the VMs and volume groups.
Create an out-of-band snapshot S1 for the PD on ROBO with no expiration.
Create an empty PD called PD1 (same name used in step 2) on the SC.
Deactivate PD1 on the SC.
Create remote sites on the ROBO cluster and the SC.
Retrieve snapshot S1 from the ROBO cluster to the SC (via Prism on the SC).
Ship the SC to the datacenter.
ReIP the SC.
Create remote sites on the SC cluster and on the datacenter main cluster (DC1).
Create PD1 (same name used in steps 2 and 4) on DC1.
Deactivate PD1 on DC1.
Retrieve S1 from the SC to DC1 (via Prism on DC1). Prism generates an alert here, but though it appears to be a full data replication, the SC transferred metadata information only.
Create remote sites on DC1 and the ROBO cluster.
Set up a replication schedule for PD1 on the ROBO cluster in Prism.
Once the first scheduled replication is successful, you can delete snapshot S1 to reclaim space.

To get all of the best practices please download the full document here, https://portal.nutanix.com/#/page/solutions/details?targetId=BP-2083-ROBO-Deployment:BP-2083-ROBO-Deployment

The last couple of years I am a huge fan of backup software that removes the need for having proxies. Rubrik provides a proxy-less backup solution by using the Nutanix Data Services Virtual IP address to talk directory to each individual virtual disk that it needs to back up.
Rubrik and Nutanix have some key advantages with this solution:
• AOS 5.1+ with version 3 API’s provides change region tracking for quick efficient backup with no hypervisor based snap. This allow for quick and efficient snapshots.
• With AHV and data locality, Rubrik can grab the most recently changed data without flooding the network which can happen when the copy and VM might not live on the same host. For Nutanix the reads happen locally.
• Rubrik has access to ever virtual disk by making an iSCSI connection to bypass the need of proxies.
• AOS can redirect the 2nd RF copy away from a node with it’s advanced data placement if the backup load becomes too great during a backup window. Thus protecting your mission critical apps that running 24-7.
• Did I mention no proxies? 🙂

Stop by the Rubrik booth and catch their session if your at .Next this week.