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How to reclaim space from virtual machines snapshots

Thavamaniraja ‎02-17-2016 09:03 AM - edited ‎02-22-2016 10:34 AM

In server virtualization, effectively utilizing the storage is a key in order to maximize the return on investment (ROI). Storage is lost in lots of places in a virtualized environment. One such example is storage consumed by virtual machine (VM) snapshots.

Virtual machine snapshots preserve the state and data of the virtual machines at a specific point in time. Though the maximum number of snapshots supported by VMware in a chain is 32, they recommend that you use only 2-3 snapshots in a chain. Large snapshot files can fill up available space causing all virtual machines running on that host to become inoperative until corrective action is taken. An excessive number of delta files in a chain (caused by an excessive number of snapshots) or large delta files may cause decreased virtual machine and host performance.

For effective utilization of storage and the best performance of virtual machines and the host, you should identify the virtual machines having snapshots, delete the snapshots on a regular basis. Identifying the VMs with snapshots could be easy task at the virtual server level but it is a challenging and time consuming task if you would like to find these details at the environment level.

HPE Storage Operations Manager is here

HPE Storage Operations Manager (SOM) is loaded with Virtual Server Analytics dashboards and makes it easy to identify the virtual machines that are having snapshots along with its reclaimable storage for your environment.

Let’s understand few terms before we dive deep

Count is the number of snapshots of each VM.

Size(GiB) is the total size of all snapshots related files including – delta.vmdk, .vmsd and .vmsn files for a given virtual machine. This would be your exact amount of reclaimable storage.

Let’s look at the dashboard

In SOM, click on Analytics for Virtual Servers dashboard from Analytics and Dashboards workspace. “Top 10 Virtual Machines by Snapshot Count” (Figure 1) chart shows the Top 10 Virtual Machines with the highest number of snapshots. The information shown here is handy when you are looking for Top 10 Virtual Machines by the snapshot count at the environment level.

Figure 1 – Top 10 Virtual Machines by Snapshot Count

Top 10 Virtual Machines by Snapshot Count.jpg

“Top 10 Virtual Machines by Snapshot Size (GiB)” (Figure 2) chart in the dashboard shows the Top 10 Virtual Machines with the largest snapshot size. This chart helps in identifying the Top 10 virtual machines with the largest snapshot size at the environment level.

Figure 2 – Top 10 Virtual Machines by Snapshot Size(GiB)

Top 10 Virtual Machines by Snapshot Size(GiB).jpg

Well, now that you have the details on Top 10 virtual machines by the snapshot count and snapshot size, you may be interested in identifying all virtual machines having snapshots for your environment.

SOM also offers a table All Virtual Machines by Snapshot Size(GiB) to lists all virtual machines having snapshots sorted by the reclaimable space, as shown in Figure 3.

Figure 3 – All virtual machines by snapshot Size(GiB)

All virtual machines by snapshot Size(GiB).jpg

The Virtual Machines tab in Host properties page helps you in identifying virtual machines that are having snapshots on a specific ESX server, as shown in Figure 4.

Figure 4 – Virtual Server properties page showing snapshot details

Virtual Server properties page showing snapshot details.jpg

The VM snapshot data is also shown in Virtual Machines table view under Hosts group in Inventory workspace, as shown in Figure 5. This view lists all virtual machines in your environment in a single view and can be sorted and/or filtered based on Snapshot Count and Snapshots Size(GiB). VMs that haven’t had a snapshot will have 0 snapshot count and 0 snapshot size.

Figure 5 – Virtual Machines inventory view showing snapshot details

Virtual Machines inventory view showing snapshot details.jpg

Now you have the details of all virtual machines having snapshots, with the confirmation of server admin, you are good to delete the snapshots in order to reclaim storage space consumed by snapshots and ensure optimal performance of virtual machines and the host.

On a closing note, virtual server analytics offered by SOM will ease your life by presenting a list of virtual machines having snapshots with the exact amount of reclaimable storage handy.

Refer to blog post How to find and reclaim storage from virtual machines to know how to reclaim storage from powered off virtual machines.

Thanks to Michael Procopio for his help in reviewing my post.

Storage Operations Manager (SOM) is a storage resource management solution that helps you reduce total costs of storage operations and increase productivity.  Start your free trial today.

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About the Author

Thavamaniraja

Sr. Software Engineer with HP Software, part of Storage Resource Management group with nearly 10 years of experience.

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