Storage snapshots offer incredible advantages in many areas. From applications testing to a form of prevention against ransomware and even to tight integration with Backup application requestors. There are different types of storage snapshots and surely each one of them is the perfect fit for specific scenarios. The purpose of this article is to provide a quick overview on HPE Application Snapshot Manager. This solution in fact, can operate both Point-In-Time (PIT) and Application Aware Snapshots.
What’s the difference?
In general, when the storage controller takes a snap of the volume this tends to “copy” all the written files in the sectors into a new storage area. Which is great. What if these files are VMs running? Let’s think about *.vmdk in the case of VMware or *.vhdx in the case of Hyper-V. In this case the storage snapshot is not transactionally consistent as the volume snapshot might have been taken when applications were running. For example enterprise applications like Microsoft Active Directory, SQL and Oracle Databases, Exchange and many others simply cannot stop running just to take storage snapshots or even backups. From this perspective there are two types of approach: VSS snapshots and PIT.
VSS snapshots can be used as transportable snapshots that can be copied or mounted onto a different server for restoring purposes. VSS snapshots leverage the Microsoft VSS framework which allows to interact with VSS aware applications (eg, AD, SQL, SharePoint, Exchange..) quiesce these applications before taking a volume snapshot. This allows a consistent restore as no data was pending or still running into server’s memory.
PIT snapshots are created by the SAN storage controller directly (as a point in time) and might not include changes to data blocks that are in flight (still running into server’s RAM Memory) and not yet committed to disk which is effectively sitting on the volume. As a result such applications might not be fully recoverable and some data might be lost. This is one of the key requirements for highly transactional applications like Databases and other applications with high IOPS requirements.
The solution is to make the storage snapshots application aware. The HPE Application Snapshot Manager assists in the creation of transactionally consistent volume snapshots for applications that follow the Microsoft VSS framework. In this article the install and configuration steps for an HPE StoreVirtual VSA running on VMware vSphere environment. It requires the installation of this component directly on the VMware vCenter or a Windows Server that can communicate with vCenter (same subnet) and is assigned as a Server to into the CMC console to volume where the storage snapshots will occur.
Install HPE Application Snapshot Manager
The HPE Application Snapshot Manager is installed by default together with the HPE Central Management Console. Since the first install I have upgraded the LeftHand OS components on the StoreVirtual appliance. As part of the upgrade process there is also a new version of the HPE Application Snapshot Manager component. This wizard is essentially the same for a new installation.
As a single component it is also available for download directly from the HPE Software Depot. Prior to install the HPE Application Snapshot Manager the Windows server requires .Net 3.5.
Next is to specify the Network Port the HPE Application Snapshot Manager will use to read the CIM schema information.
In case existing volume snapshots or scheduled ones are running these should be temporarily paused.
At this point the in install wizard has the information to install/upgrade the necessary components. The process is very quick.
In order to use the HPE Application Snapshot Manager it is necessary to specify the credentials to access the HPE Management Groups previously created. This is necessary to “read” the configuration and content of the volumes.
This screen will appear only when updating existing installations.
At this point on the Windows Server where the component is installed or updated it is possible to verify if the VSS Hardware Provider component is successfully installed. From an admin command prompt this can be done with:
“vssadmin list providers”
which shows the built-in System and Software Providers plus the new one which directly interacts with the Storage Controller on the HPE StoreVirtual to manage the volume snapshots.
Next step is to provide the credentials to access the desired Management Groups. The Credentials wizard will help with the setup and verification.
By default, the credentials wizard has already identified the available Management Groups on the network. Let’s provide the credentials and hit on test to verify the connection.
In this case the test utility is already showing the correct IP Address for the storage system and when more than one are available it is possible to verify multiple arrays. For example when HPE StoreVirtual storage replication is used.
The verification test is now complete and the wizard will save in its own cache the credentials for later used until updated.
Now everything is ready to instruct the HPE StoreVirtual array to take application aware storage snapshots. All is required is the address and credentials for the vCenter managing the Datastores sitting on the volumes provided by the HPE StoreVirtual servers. Let’s make sure the VMware tools are installed on the VMs for the desired datastores.
In cases where the VSS fails or times out to quiesce the applications (eg. too many VMs, or slow storage backend) the workaround is to disable the virtual machine memory snapshot.
One last configuration with the VMware integration options is the ability to choose the type of snapshot the HPE StoreVirtual array will create. Essentially there are 4 options available:
- Full Backup – All files in the volume are backed up in the snapshot.
- Incremental Backup – Files created or changed since the last full or incremental backup are saved.
- Differential Backup – Files created or changed since the last full backup are saved.
- Copy Backup With No History Update – Files on disk will be copied to a backup medium regardless of the state of each file’s backup history, and the backup history will not be updated. This is the default option.
All these options are supported by the majority of application requestors and namely Backup applications. Very interestingly the option to copy volume server assignments to 3rd party VSS snapshots. This means that selected settings on the snapshot type will be passed on to an application requestor.
From an HPE StoreVirtual perspective and in particular from a storage point of view there is now the option to enable the application aware volume snapshots (namely Application-Managed Snapshot) for an application and file consistent snapshot for those applications that can leverage the Microsoft VSS framework and for which the VSS writers exist with the application.
This feature is available for any type of volume snapshot that HPE StoreVirtual can manage:
- Storage Snapshots
- Scheduled Snapshots
- Remote Snapshots
- Remote Scheduled Snapshots
- Remote SmartClones
The next articles will explore how to run Backup and Restore jobs from Storage Snapshots leveraging the HPE StoreVirtual storage arrays.