Storage Considerations with App Volumes

With the release of VMware App Volumes 2.6 VMware has added the ability to manage multiple copies of the same AppStack as a single AppStack with in the App Volumes Manager interface. Storage groups can be used to group datastores together, this way you can add an AppStack to a storage group and the App Volumes Manager will place the AppStack in the best place based on your Distribution Strategy. For Distribution Strategy you have 3 options:

  • Spread – Distribute files evenly across all the storage locations.
  • Spillover – Distribute files by filling each storage location before using the next one.
  • Round-robin – Distribute files by sequentially using the storage locations.

When a user logs in, the App Volumes Manager will manage the connection to the relevant AppStack. When the Spread option is chosen the App Volumes Manager will use Round-robin to connect users to the AppStack VMDK to spread the connections over the datastores.

This will make managing and assigning AppStacks to large numbers of users much easier for the App Volumes administrators.

The graphic below gives you a high level look at how this affects storage.

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Now the question that an architect needs to answer is how many VMDK’s will be needed to support a single AppStack with in the App Volumes manager. The table below is the recommended number of connections per VMDK depending on storage type.

Storage Type VMFS NFS Flash Storage
Recommended Maximum connections per VMDK 128 250 1000

Using this table it make the decisions basic math. The following equation can be used to figure out just how many VMDK’s will be needed per AppStack.

Number of users / Maximum connections per storage type = Number of VMDK’s needed or datastores

So if you were assigning an AppStack to 500 users in you organization and the storage type the AppStack VMDK’s is stored on is VMFS the calculation would be

500 (Users) / 128 (max connections per datastore) = 3.9

A single copy of the AppStack VMDK could then be placed on a datastore with in the Storage Group and the App Volumes Manager would replicate that VMDK to all the datastores with in the storage group.

Now the above calculation helps with number of users connecting to AppStack VMDK’s however you will also need to take in to consideration the number of IOPS needed for the software in the AppStack. For best performance this may mean you need more datastores to spread the load across more disks.

How to configure Storage Groups for AppStacks

The following will walk you through how to configure a storage group in App Volumes.

  1. Log in to your App Volumes Manager
  2. Click Infrastructure, Storage Groups, Create Storage Group

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  1. Give the Storage group a Name, then choose the options that are required, then click Create

Note: If there are already AppStacks on the storage that will be included in the storage group check the box Automatically Import AppStacks

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  1. Click Create

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Once the storage group is created any new AppStacks created on a datastore with in the storage group will be automatically copied to all the datastores with in the storage group.

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