Requirements and restrictions

The following software licenses are required:

• Global-active device
• TrueCopy (for GAD+TC configurations)
• Universal Replicator (for GAD+UR configurations)
• Remote Replication Extended (for 3DC delta resync (GAD+UR) configurations)

You can use Maintenance Utility or CCI to view and manage the software licenses.

User interfaces (UIs)

You can use the following UIs to perform GAD operations:

• Command Control Interface (CCI) (CLI)

  CCI must be installed on a host connected to the primary and secondary storage systems.

  A CCI command device is required on the primary and secondary storage systems.

• VSP One Block Administrator (GUI)

  VSP One Block Administrator can be used for some GAD operations. Only the configurations that use consistency groups are supported. If you perform detailed management or troubleshooting, use CCI.

  For more information, see the VSP One Block Administrator User Guide.

• REST API

Secondary storage systems for VSP One Block 85

VSP One B85 can be connected to:

• VSP One B85 (all versions)
• VSP 5000 series (90-09-29 or later)

Note: Storage system interoperability depends on the models, microcode levels, and physical data paths. For details, see the TC, UR, GAD Replication Intermix site at https://compatibility.hitachivantara.com/products/replication-intermix.

Secondary storage systems for VSP One Block 20 series

VSP One B20 series can be connected to VSP One Block 20 series (all versions).

VSP One B20 series can be connected to:

• VSP One B20 series: All versions
• VSP 5000 series: DKCMAIN 90-09-29 or later
• VSP E1090, VSP E590, VSP E790, VSP E990: DKCMAIN 93-07-22 or later
• VSP G/F350, G/F370, G/F700, G/F900: DKCMAIN 88-08-12 or later
• VSP G200, G400, G600, G800 and VSP F400, F600, F800: DKCMAIN 83-05-53 or later (for 83-05-xx), 83-06-25 or later (for 83-06-xx)

Note: Storage system interoperability depends on the models, microcode levels, and physical data paths. For details, see the TC, UR, GAD Replication Intermix site at https://compatibility.hitachivantara.com/products/replication-intermix.

GAD 3DC delta resync (GAD+UR)

3DC delta resync in a GAD+UR configuration is supported in the following configurations:

VSP One Block 85 as primary storage system

VSP One B85 can be connected to:

• VSP One B85 (all versions)
• VSP 5000 series (90-09-29 or later)

VSP One Block 20 series as primary storage system

VSP One B26 and VSP One B28 can be connected to:

• VSP One B26 (all versions)
• VSP One B28 (all versions)
• VSP E series (93-07-23 or later)
• VSP 5200 (90-09-25 or later)
• VSP 5600 (90-09-25 or later)

External storage systems or servers (for quorum disk)

• The storage system or server must be supported for attachment using Universal Volume Manager. The server can be attached using iSCSI or can be cloud-based.

  For the latest information about external storage support, see the product compatibility guide at https://compatibility.hitachivantara.com/products/uvm.

• The maximum distance between the external storage system and the primary site and secondary site is 1,500 km.

Licensed capacity

• If creating a GAD pair will exceed the available licensed capacity, the pair creation operation will fail.
• If the actual licensed capacity exceeds the available licensed capacity, pair creation cannot be performed. In addition, 30 days after the licensed capacity is exceeded, only pair split and pair delete operations are allowed.
• If a V-VOL is used as a GAD P-VOL or S-VOL, the page size assigned to the V-VOL is counted as licensed capacity for GAD. However, for a data-reduced volume (V-VOL with capacity saving enabled on VSP One B20 series, DRS-VOL on VSP One B85), the GAD licensed capacity is the capacity before data reduction (savings).

Host platforms (when connecting the host and the storage system using Fibre Channel or iSCSI)

Partial list of supported host platforms:

• AIX
• HP-UX
• Red Hat Enterprise Linux
• Solaris
• SUSE Linux
• VMware ESX
• Windows Server

This is not a complete list. For the latest information about supported host platforms, see the storage interoperability matrix at https://compatibility.hitachivantara.com/products/interop-matrix.

Host platforms (when connecting the host and the storage system using NVMe-oF)

(VSP One B85) Supported on all versions.

(VSP One Block 20 series) Volumes connected to a host using NVMe-oF can be used as GAD pair volumes.

For the latest information about supported host platforms, see the storage interoperability matrix at https://compatibility.hitachivantara.com/products/interop-matrix.

Maximum number of storage systems that can be connected

You can create GAD pairs from one primary storage system to up to 15 secondary storage systems.

SCSI commands

• The Thin Provisioning function of Windows Server 2012 is supported.
• The SCSI-2 Reserve command, the SCSI-3 Persistent Reserve command, and the VAAI command are supported.
• In the environment with SCSI-3 Persistent Reserve enabled, Reservation Key must be registered for each path (host group) on which an I/O operation is performed. Therefore, to perform an I/O operation from the host to both a P-VOL and an S-VOL, make sure to register Reservation Key for each path (host group) of both the P-VOL and the S-VOL. The registered Reservation Key information is duplicated between GAD pairs. If you want to remove a host reservation from the storage system, make sure to remove the host reservations on both the P-VOL and the S-VOL. If you remove only one host reservation, a Reserve Conflict might occur when the host is replaced.

Physical paths connecting the primary and secondary storage systems

• Maximum distance between the primary and secondary storage systems: 500 km
• Maximum value of the round-trip delay, including delay due to failure of an interface device: 20 ms

  Requirements for connecting storage systems that are more than 100 km away from each other:

  • The primary and secondary storage systems must be connected by Fibre Channel interfaces.
  • The line speed between the primary and secondary storage systems must be 1 Gbps or more.
  • Host mode option (HMO) 51 must be set to ON.

  If the primary and secondary sites are more than 100 km away from each other, please contact customer support.

• The following interfaces can be used:
  • Fibre Channel, 32-Gbps or 64-Gbps (VSP One B20 series) link speed

    (Fibre Channel Board 32GB V2 and Fibre Channel Board 64GB V2 are not supported.)

  • iSCSI, 10-Gbps (VSP One B20 series) or 25-Gbps link speed

  NVMe-oF and NVMe/TCP are not supported.

  For details about supported firmware versions of interfaces that can be used for physical paths, see Planning physical paths.

• Port type: Fibre Channel, iSCSI with direct, switch, or channel extenders. For details, see Connection types.

  (VSP One B20 series) For the combinations of models and channel boards that support the iSCSI interface, see the Supported iSCSI interface combinations table below.

Remote paths and path groups

• Maximum number of remote paths per path group: 8
• Maximum number of path groups per storage system: 64 (sum of the path groups used by TC and UR)
• Path group ID: 0-255.
• Set remote paths for each path group.
• When you create a GAD pair, if you specify a path group ID used by TrueCopy or Universal Replicator, the GAD pair uses the same physical path as TrueCopy or Universal Replicator. If you want a different physical path for a GAD pair, prepare a physical path that is not used by TrueCopy or Universal Replicator and specify a path group ID not used by TrueCopy or Universal Replicator.
• The path group is specified during the create pair operation and cannot be changed by resynchronization.
• The remote path must be set by each path group of the storage systems at the primary site and the secondary site.

  You can also use multiple path groups with the same combination of storage systems at the primary and the secondary sites.

Virtual storage machines (VSMs)

The maximum number of virtual storage machines (VSMs) and the supported configurations depend on the storage system model. For details, see the Provisioning Guide for your storage system.

• Maximum number of VSMs :
  • VSP One B85: 15
  • VSP One B20 series: 15
• Maximum number of GAD volumes per VSM:
  • VSP One B85: 49,151
  • VSP One B28: 49,151
  • VSP One B26: 32,767
  • VSP One B24: 16,383
• GAD pari requirements fpr VSMs:
  • You can create GAD pairs using volumes in VSMs.
  • When you want to create a GAD pair using volumes in VSMs, the VSM for the volume in the secondary site must have the same model and serial number as the VSM for the volume in the primary site.
• Restrictions for VSM-based GAD pairs:
  • You can create GAD pairs using volumes in VSMs. When you want to create a GAD pair using volumes in VSMs, the VSM for the volume in the secondary site must have the same model and serial number as the VSM for the volume in the primary site.
  • If a virtual storage machine (VSM) of the secondary storage system has the same virtual LDEV ID as the P-VOL, GAD pairs cannot be created. If volumes are not created and only an LDEV ID exists, the virtual LDEV ID must be deleted before GAD pairs can be created.

Maximum number of GAD pairs for VSP One Block 85

Maximum number of GAD pairs for a single VSM or a single storage system

For external volumes, DP-VOLs, and DRS-VOLs:

(maximum-number-of-volumes-on-a-single-VSM) - (number-of-quorum-disks)

Maximum number of GAD pairs for VSP One Block 20 series

Maximum number of GAD pairs for a single VSM or a single storage system

If all volumes are external volumes:

• VSP One Block 28: 49,152 - number-of-quorum-disks
• VSP One Block 26: 32,768 - number-of-quorum-disks
• VSP One Block 24: 16,384 - number-of-quorum-disks

If all volumes are DP-VOLs:

• VSP One Block 28: 49,152 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 26: 32,768 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 24: 16,384 - number-of-pool-volumes - number-of-quorum-disks

If all volumes are DP-VOLs with the compression setting:

• VSP One Block 28: 21,760 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 26: 21,760 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 24: 16,384 - number-of-pool-volumes - number-of-quorum-disks

If all volumes are DP-VOLs with the compression and deduplication settings:

• VSP One Block 28: 21,754 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 26: 21,754 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 24: 16,376 - number-of-pool-volumes - number-of-quorum-disks

If all volumes are created with data-reduced volumes with the compression setting:

• VSP One Block 28: 32,640 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 26: 32,640 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 24: 16,384 - number-of-pool-volumes - number-of-quorum-disks

If all volumes are created with data-reduced volumes with the compression and deduplication settings:

• VSP One Block 28: 32,630 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 26: 32,630 - number-of-pool-volumes - number-of-quorum-disks
• VSP One Block 24: 16,376 - number-of-pool-volumes - number-of-quorum-disks

For details about calculating the maximum number of pairs based on the number of bitmap areas or cylinders used in volumes, see Maximum number of GAD pairs.

Pair volumes

• Provisioning type:
  • Dynamic Provisioning virtual volumes (DP-VOLs)

    For DP-VOLs, the GAD P-VOL and S-VOL must have the same Data Direct Mapping attribute. You cannot create a GAD pair when the Data Direct Mapping attribute is enabled for one DP-VOL but not the other.

  • External volumes

    Note that external volumes cannot be used in VSM auto-configuration.

• Volume attribute

  The volume attribute (shown as VOL_ATTR by the raidcom get ldev command) of the P-VOL and S-VOL must be same. You cannot create a GAD pair using volumes with different volume attributes. Note that internal volumes, external volumes, and DP-VOLs have different volume attributes. Enabling or disabling the capacity saving function of DP-VOL does not affect the volume attributes.

• Emulation type: OPEN-V
• T10 PI: The same T10 PI attribute must be set for the P-VOL and S-VOL.
• SAN boot: You can use GAD pair volumes for SAN boot.
• Volume size: The P-VOL and S-VOL must be equal in size.
• Maximum volume size:
  • DP-VOL: 268,435,456 MB (549,755,813,888 blocks)
  • External volume: 4,194,304 MB (8,589,934,592 blocks)

Pair connected to host by FC32G

Primary storage: VSP One B85

Secondary storage:

• VSP One B85: all versions
• VSP 5000 series: 90-09-29 or later

Primary storage: VSP One B20 series

Secondary storage:

• VSP One B20 series: all versions
• VSP 5000 series: 90-09-23 or later
• VSP E series: 93-07-22 or later
• VSP G/F350, G/F370, G/F700, G/F900: 88-08-12 or later

Pair connected to host by FC64G

Primary storage: VSP One B85: A0-05-41 or later

Secondary storage:

• VSP One B85: A0-05-41 or later
• VSP 5000 series: 90-09-31 or later

Primary storage: VSP One B20 series

Secondary storage:

• VSP One B20 series: all versions
• VSP 5000 series: 90-09-24 or later
• VSP E series: 93-07-23 or later
• VSP G/F350, G/F370, G/F700, G/F900: 88-08-13 or later

GAD configurations using volumes (namespaces) that are connected to a host using 32-Gbps NVMe-oF

Primary storage: VSP One B20 series

Secondary storage:

• VSP One B20 series: A3-03-01 or later
• VSP 5000 series: 90-09-25 or later

GAD configurations using volumes (namespaces) that are connected to a host using 64-Gbps NVMe-oF as pair volumes

GAD configurations using volumes (namespaces) that are connected to a host using NVMe/TCP as pair volumes

These configurations are not supported.

• VSP One B85: all versions

Secondary storage:

• VSP One B85: all versions
• VSP 5000 series: 90-09-31 or later

Quorum disks

A quorum disk can be a volume in an external storage system supported by Universal Volume Manager or a disk in an iSCSI server, including cloud-based virtual servers (for example, running in Azure) if the server is supported by Universal Volume Manager.

• Maximum number of quorum disks: 32 per storage system in the primary storage system and secondary storage system
• Quorum disk ID: 0 to 31
• (VSP One B85) The maximum number of GAD pairs that can be created on a quorum disk is the same as the maximum number of GAD pairs that can be created on a single virtual storage machine (VSM).
• (VSP One Block 20 series) Maximum number of GAD pairs per quorum disk:
  • VSP One B28: 49,151
  • VSP One B26: 32,767
  • VSP One B24: 16,383
• Minimum size: 12,292 MB (25,174,016 blocks)
• Maximum size: same as the maximum limit for an external volume supported by Universal Volume Manager: 4 TB
• One external volume group must be mapped to one external volume.
• Requirements for the external storage system volume:
  • The T10 PI attribute must not be enabled.
  • The Data Direct Mapping attribute must not be set.

Consistency groups (CTGs)

If different models of storage systems are connected, the maximum number of consistency groups is that of the model with the least maximum number, and the allowed range of CTG IDs is that of the model with the lowest range.

• Maximum number of consistency groups per storage system:
  • VSP One Block 26 and VSP One Block 28: 128 (CTG ID 0-127)*
  • VSP One B85: 1,024 (CTG ID 0-1023)

  * VSP One B24 does not support consistency groups.

• Maximum number of GAD pairs per consistency group: 8,192
• Quorum disk ID: The same quorum disk ID must be set for all GAD pairs in a single consistency group.
• VSM: GAD pairs in the same consistency group must be created on the same virtual storage machine.
• CTG ID: If consistency groups have the same ID but their physical storage systems are different, they are treated as different consistency groups. You can use the same consistency group ID for groups on different storage systems.

Mirrors

Mirror ID: 0 to 3

When no mirror ID is specified, 0 is automatically set.

Multi-path software

Multi-path software is required for the single-server GAD configuration and the cross-path GAD configuration (two servers).

For details, see the storage interoperability matrix at https://compatibility.hitachivantara.com/.

Cluster software

Cluster software is required for the server-cluster and cross-path GAD configurations.

For details, see the storage interoperability matrix at https://compatibility.hitachivantara.com/.

1. This combination is supported for the following firmware versions. The link-up speed is 10 Gbps.
   • VSP 5000 series: 90-09-31 or later
   • VSP One B20 series: A3-05-21 or later
2. This combination is supported for the following firmware versions. The link-up speed is 10 Gbps.
   • VSP E series: 93-07-30 or later
   • VSP One B20 series: A3-05-21 or later
3. This combination is supported for the following firmware versions. The link-up speed is 10 Gbps when 10 Gbps and 25 Gbps coexist. The link-up speed is 25 Gbps when both parties support 25 Gbps.
   • VSP One B20 series: A3-04-21 or later