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Creating Virtual Disks

Many options and customizations are available to prepare each virtual disk for a particular use.

Procedure

  1. On the Virtual Disk Management (VDM) page, select Add Disk.

  2. In the Add New Virtual Disk dialog, enter the desired attributes for the virtual disk, as described in the following table. When you are done, select Run to create the virtual disk.

    Important: Hedvig does not currently support reusing the name of a deleted Block or NFS type virtual disk. However, Hedvig's S3-Protocol Compatible Object Storage does support reusing the name of a deleted bucket.

    field

    description

    Batch

    Select the batch option to create a group of virtual disks.

    Number
    (batch only)

    Enter the number of virtual disks for batch creation.

    Base Name
    (batch only)

    Enter a descriptive name for the group of virtual disks. This name will be the same for all disks in this batch; the subsequent numbering will uniquely identify them.

    This name must contain only alphanumeric characters — no special characters or spaces.

    Important: Hedvig does not currently support reusing the name of a deleted Block or NFS type virtual disk. However, Hedvig's S3-Protocol Compatible Object Storage does support reusing the name of a deleted bucket.

    Starting At
    (batch only)

    Enter the first number for this group of virtual disks.

    Digits
    (batch only)

    Enter the number of digits for the group of virtual disks. This can be greater than the number of current digits — for future expansion. For example, you might create two disks now, but plan for more: Disk001 and Disk002, and later up to Disk999.

    Disks Will be Named
    (batch only)

    Review your naming format to adjust the previous fields, as necessary.

    Name
    (single disk)

    Enter a name for a single virtual disk. This name must contain only alphanumeric characters — no special characters or spaces.

    Important: Hedvig does not currently support reusing the name of a deleted Block or NFS type virtual disk. However, Hedvig's S3-Protocol Compatible Object Storage does support reusing the name of a deleted bucket.

    Size

    Enter a number, and select the units (GB or TB).

    Hedvig supports single block and NFS virtual disks of unlimited size.

    Note: (1) Although Hedvig allows unlimited size for virtual disks, other factors in your setup may not. For example, VMware imposes a limit of 62 TB per virtual disk per virtual machine. (2) See also Why Virtual Disk Sizes May Appear "Rounded Down".

    Disk Type

    Select the protocol: BLOCK or NFS.

    Note specifically for NFS: (1) Clustered file system is automatically enabled. (2) Block size is automatically set to 512.

    NFS Version

    Select NFS 3 or NFS 4.

    Workload Type

    (NFS only)

    VIRTUALIZATION: For virtualized environments.

    BACKUP: For use cases in which Hedvig will be a backup target that can be used with and without deduplication enabled.

    OST: For use cases in which the backup software is NetBackup, and Hedvig is the target.

    Workload Type

    NFS Protocol Supported

    VIRTUALIZATION

    NFSv3

    BACKUP

    NFSv4

    OST

    NFSv3

    Note: Virtual disks that have been enabled for backup are targets for backups only, and VMs cannot be run on them.

    Retention Policy

    Select ONE_WEEK, TWO_WEEKS, ONE_MONTH, SIX_WEEKS, TWO_MONTHS, THREE_MONTHS, NINE_MONTHS, SIX_MONTHS, ONE_YEAR, or FOREVER.

    Encryption

    Enable encryption to encrypt both data at rest and data in flight.

    Enable Deduplication

    Enable deduplication to enable inline global deduplication.

    When enabling deduplication, be aware of the following conditions:

    • Disk Residence can be either HDD or Flash.
    • Compression is automatically enabled.
    • Deduplication cannot be enabled for a block virtual disk with a Clustered File System.
    • For dual data centers with a Replication Policy of Data Center Aware, you can choose a Replication Factor of 2, 4, or 6.
    • You can create global system deduplication-enabled virtual disks for multiple combinations of data centers when the number of data centers exceeds 3.
    • You can create Rack Aware or Agnostic Replication Policy system deduplication virtual disks in a Data Center Aware Replication Policy environment.
    • You can create Agnostic Replication Policy system deduplication virtual disks in a Rack Aware Replication Policy environment.
    • Deduplication metrics are computed on demand and do not run as a scheduled task.
    • Deduplication is not supported with Erasure Coding.

    Warning: When you are upgrading your system, a non-disruptive upgrade (NDU) could be problematic for a Data Center with a Rack Aware or Agnostic Replication Policy, in an environment with deduplication-enabled virtual disks

    Clustered File System

    Enable to format a clustered file system on top of a virtual disk to be presented to multiple hosts.

    Note: (1) This is automatically enabled for an NFS virtual disk. (2) Block size is automatically set to 512.

    Description

    Enter a description (optional).

    Compressed

    Enable compression to reduce data size.

    Note: This is automatically enabled when deduplication is enabled.

    Client-side Caching

    Enable client-side caching for virtual disk blocks, to cache to local SSD or PCIe devices at the application compute tier for high performance.

    CSV

    Enable Cluster Shared Volumes for failover (HA, that is, high availability) clustering.

    A Cluster Shared Volume is a shared disk containing an NTFS or ReFS volume that isaccessible for read/write operations by all nodes in a Windows Server failover cluster.

    Protection Policy

    Select Replication or Erasure Coding.

    Replication Policy

    (options available depend on cluster type)

    Replication Policy options defined:

    • Agnostic: Also called Rack Unaware.
    • Data Center Aware: Data is spread across multiple data centers, which can include private data centers and public clouds. Selecting certain data centers will automatically set the replication factor.
    • Rack Aware: Data is spread across physically distinct racks in a single data center. No more than one copy of the same data is placed on the same rack, in order to avoid single-rack failure.

      Replication Policy options available by cluster type:

    • Rack Aware and Data Center Aware Cluster: The default is Data Center Aware. [Agnostic is not available.] For Data Center Aware, you select one or more data centers from Pick Data Center(s). For Rack Aware, you select only one data center.
    • Rack Aware Cluster, with no Data Center: The only option available is Rack Aware.
    • Rack Aware Cluster, with one Data Center: The only option available is Rack Aware. The data center is automatically selected.
    • Data Center Aware Cluster: The default is Data Center Aware. You select one or more data centers from the Pick Data Center(s) list.
    • Agnostic Cluster: The only option available is Agnostic.
    • Single Data Center Cluster, with no Rack: The options available are Agnostic and Data Center Aware. For the latter, the data center is automatically selected.

    Pick Data Center(s)

    If the cluster has associated data centers, and Data Center or Rack Aware isselected for Replication Policy, then select the desired Data Centers from the list provided.

    Replication Factor

    Specify the number of replicas (1 to 6) to create for each virtual disk. A replication factor of 3 is the default and is highly recommended.

    Important: A replication factor of 1 offers no copy protection. Use it only when data protection is guaranteed outside the Hedvig system.

    Erasure Config

    Erasure Coding (Erasure Config RS_4_2) is supported for the following setups:

    • For Hedvig's S3-Compatible Object Storage, with a minimum of six nodes.
    • For NFS as a Backup Target for Commvault, with a minimum of three nodes. [However, it is not currently supported for clusters with a Rack Aware or a Data Center Aware replication policy.]

    Note: Deduplication is not supported with Erasure Coding.

    Block Size

    For a block virtual disk, select the block size [512, 4096 (4k), or 65536 (64k)]. For an NFS virtual disk, the only allowed value is 512.

    Note: (1) If deduplication is enabled, block size is set to 4096 automatically. (2) See also Factors Affecting Virtual Disk Block Size and Other Options.

    Residence

    Select the Hedvig Storage Pool type in which to store the virtual disks:

    • HDD, where the system will auto-tier, that is, hot data will be placed on the highest performing media — typically SSD assets (if present) — while cold data will reside on spinning hard disks.
    • Flash, where the virtual disk will be pinned only to SSD assets (which must be present) in the storage cluster, essentially creating an all-flash array for the virtual disk.

Last modified: 8/25/2021 2:38:16 PM