• Overview

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    Overview

    Unity SMB support

    All Unity releases support SMB 1 through SMB 3.02, which supports enhancements such as Continuous Availability, Offload Copy, Protocol Encryption, Multichannel, and Shared VHDX Support. Some of these features, such Multichannel and Shared VHDX Support, do not require any special configuration on the Unity system. For Multichannel, if there are multiple interfaces created on multiple ports, the SMB 3 protocol automatically uses all available TCP connections for a single SMB session. Shared VHDX support provides the ability to enable Virtual Hard Disk sharing on Hyper-V to share a virtual disk between multiple nodes.

    Starting with Unity OE version 4.2, SMB 3.1.1 is also supported, which adds reliability enhancements for Continuous Availability (CA) for Hyper-V Cluster Client Failover (CCF), and improved security and encryption traffic performance. The SMB version used depends on the client operating system.

    SMB support is enabled on the NAS server level during or after creation, allowing you to create SMB-enabled file systems on that NAS Server. When enabling SMB support on a NAS server, the server can either be standalone or Active Directory domain-joined. Domain- joined NAS servers are placed in the OU=Computers, OU=EMC NAS Servers organizational unit by default.

    Unity also supports the Microsoft Distributed File System (DFS) Namespace, which provides the ability to present shares from multiple file systems through a single mapped share. You can configure a Unity SMB server as a standalone DFS root node or as a leaf node on an Active Directory DFS root.

    DFS Replication (DFS-R) is not supported by Unity systems. If replication is required, the native asynchronous replication feature can be used to replicate the file system instead.

    SMB file systems and shares have the following additional advanced protocol options. All of these options, except for Oplocks Enabled, are disabled by default.

    Protocol option
    Level
    Sync Writes Enabled
    File system
    Oplocks Enabled
    File system
    Notify on Write Enabled
    File system
    Notify on Access Enabled
    File system
    Continuous Availability
    Share
    Protocol Encryption
    Share
    Access-Based Enumeration
    Share
    Branch Cache Enabled
    Share
    Offline Availability
    Share

    Unisphere storage provisioning

    Storage provisioning is the process of allocating available drive capacity to meet the capacity, performance, and availability requirements of hosts and applications. When you provision storage with Unisphere, you create storage resources to which hosts and applications can connect in order to access storage.

    When you provision a storage resource in Unisphere, the system uses thin provisioning by default. This type of provisioning can improve storage efficiency while reducing the time and effort required for monitoring and rebalancing existing pool resources. Organizations can purchase less storage capacity up front, and increase available drive capacity (by adding drives) on an on-demand basis, and according to actual storage usage, instead of basing drive requirements in the requests or predictions of connected hosts. Thin provisioning allows multiple storage resources to subscribe to common storage capacity within a pool, while the system allocates only a portion of the physical capacity requested by each storage resource. The remaining storage is available for other storage resources to use.

    All storage resources require some amount of metadata from the pools where the storage resources were provisioned.
    Thick and thin provisioning

    The following table describes the differences between thick and thin provisioning:

    Table 1. Differences between thick and thin provisioning
    Provisioning type
    Description
    Thick provisioning
    The amount of storage requested for a storage resource is exclusively allocated for it. This storage is reserved, and the unused portion cannot be used or distributed among other storage resources associated with the same pool.
    Thin provisioning
    The amount of storage requested for a storage resource is not immediately allocated for it. Instead, the system allocates an initial quantity of storage to the storage resource. When the amount of storage consumed within the storage resource approaches the limit of the current allocation, the system allocates additional storage to the storage resource from the pool.

    Thin provisioning is required for data reduction.

    Figure 1. Difference between thick and thin provisioning

    An image that highlights the difference between standard provisioning and thin provisioning.

    Creating a thin storage resource

    When you create a thin storage resource, you specify a target size for the resource. The size represents the maximum capacity to which the storage resource can grow without being increased by an administrator. The system reserves only a portion of the requested size, called the initial allocation. The requested size of the storage resource represents a subscribed quantity. Additional storage is allocated on-demand.

    When a host or application uses approximately 75% of its initial allocation, an additional incremental quantity of storage is automatically allocated to the storage resource. The incremental allocation process continues until the quantity of storage allocated for the storage resource reaches the limit determined by its target size.

    A storage resource may appear full when data copied or written to the storage resource is greater than the space available at that time. When this occurs, the system begins to automatically extend the storage space and accommodate the write operation. As long as there is enough extension space available, this operation will complete successfully.
    Pool subscription levels

    Because storage resources can subscribe to more storage than is actually available to them, pools can be over-provisioned to support more storage capacity than they actually possess. The system automatically generates notification messages when total pool usage reaches 85% of the pool's physical capacity. (You can customize this threshold.)

    Thin provisioning best practices

    The following general rules can help determine the best environments in which to use thin provisioning:

    • Thin provisioning provides the benefit of space efficiency. It is recommended that you choose thin provisioning for a storage resource (selected by default), unless absolute and predictable performance is a higher requirement than space efficiency. In some workload environments, performance can actually improve with thin provisioning.
    • Environments that can benefit from thin provisioning include:
      • Document repositories with rapidly rising capacity requirements. These repositories can benefit greatly from the improved capacity utilization offered by thin provisioning, provided their environments meet the previously outlined criteria.
      • Software development and source code repositories. These repositories are well-suited to thin provisioning, because their environments can usually tolerate some level of performance variability.
    • Thin provisioning works best in file system environments where files are not frequently deleted. Many file systems do not efficiently reuse the space associated with deleted files, which can result in an allocated but unused space in the thin-provisioned file system.
    • Consider the space consumption characteristics of databases before using thin provisioning. Some databases pre-allocate the storage space for data before writing to it. This space is allocated within a thin-provisioned storage resource, and this can reduce the capacity utilization within the pool. For more information, consult your database vendor documentation.
    Recommendations for migrating data to a new file-based storage resource

    Although there are several benefits to creating a new storage resource using thin provisioning, you must consider the following recommendation when migrating data from an old storage resource to a new file-based storage resource:

    If the data you are migrating will occupy 25% or more of the space available in the new file-based storage resource, it is recommended that you do not initially enable thin provisioning for the storage resource. Enabling thin provisioning for the new storage resource before migrating data to it can cause performance issues. To avoid performance issues, initially create the new storage resource with thin provisioning disabled and the size set to slightly larger than the amount of data being migrated. Once the storage resource is created, modify it to enable thin provisioning, increase its size, and then start migrating data to your storage resource. Consider increasing the size of the storage resource based on the amount of data you expect to be added over time.

    Advantages of thin and standard provisioning

    Thin provisioning provides the following advantages:

    • Provides the most efficient allocation of storage capacity based on usage.
    • Promotes ease of use in setting up and managing pool capacity.
    • Minimizes the host impact of adding pool resources based on host storage usage.
    • Optimizes storage usage in situations where space consumption is difficult to forecast.

    Planning considerations

    The following table summarizes the tasks to perform in a Windows Server environment before you start configuring SMB on your Unity system. For more information on performing these tasks, see the Unity online help and the Windows Server documentation.

    1. Configure one or more DNS servers.
    2. If you are joining the NAS server to the Active Directory (AD), configure at least one NTP server on the storage system to synchronize the date and time. It is recommended that you set up a minimum of two NTP servers per domain to avoid a single point of failure.
    3. Create a domain account in Active Directory.
    4. Optionally configure VLANs and tenants if you plan to implement multi-tenancy.

    Related features and functionality information

    Specific information related to the features and functionality described in this document is included in the following for Unity:

    • Unisphere Online Help
    • Configuring Hosts to Access SMB File Systems
    • Configuring Replication
    • Unisphere Command Line Interface User Guide
    • Service Commands Technical Notes

    The complete set of customer publications is available on the Online Support website at http://Support.EMC.com. After logging in to the website, click the Support by Product page, to locate information for the specific feature required.