Configuring Storage : Configuring LUNs
  
Configuring LUNs
You configure block disk (Fibre Channel), Edge Local, and iSCSI logical unit numbers (LUNs) in the LUNs page.
Typically, block disk and iSCSI LUNs are used to store production data. They share the space in the blockstore cache of the associated Edges, and the data is continuously replicated and kept synchronized with the associated LUN in the data center. The Edge blockstore caches only the working set of data blocks for these LUNs; additional data is retrieved from the data center when needed.
Edge Local LUNs are used to store transient and temporary data. Local LUNs also use dedicated space in the blockstore cache of the associated Edges, but the data is not replicated to the data center LUNs.
Fibre Channel LUN configuration steps in ESXi
To configure storage arrays using Fibre Channel, Core-v leverages raw device mapping (RDM) functionality through VMware ESXi. To configure a Fibre Channel LUN, you must do the following tasks in the ESXi server where Core-v is deployed:
•  Expose the Fibre Channel LUNs to the ESXi server.
•  Assign the discovered Fibre Channel LUNs as raw device mappings (RDM).
•  Ensure that NPIV is disabled.
You can then discover and configure the Fibre Channel LUN as a block-disk LUN in the SteelFusion Core Management Console. For details, see To configure a LUN. After configuring the block-disk LUN in the SteelFusion Core Management Console, you must return to the ESXi server to configure high availability for the new LUN:
•  In ESXi, modify the storage group to which the LUN belongs to expose the LUN to both ESXi servers running the Core failover peers.
•  Ensure that the LUN is raw-data mapped (RDM) to both Core-v appliances.
•  Ensure that the SCSI bus number of the RDM LUN is the same on both ESXi servers.
For details about all preconfiguration and postconfiguration steps for Fibre Channel LUNs, see the Fibre Channel on SteelFusion Core Virtual Edition Solution Guide.
Block-disk LUN considerations
Block-disk LUNs for Fibre Channel are distinct from iSCSI LUNs in several important ways:
•  No MPIO configuration - There is no MPIO configuration for block-disk LUNs. Multipathing is instead performed by the ESXi system.
•  No Volume Snapshot Service (VSS) snapshot support - While all other snapshot features are supported, Windows VSS is not.
•  SCSI reservations - Not taken on block-disk LUNs.
•  Additional HA configuration required - Configuring high-availability for Core-v failover peers requires that each appliance be deployed on a separate ESXi system. Similarly, block-disk LUNs must be exposed to both systems. For details, see Fibre Channel LUN configuration steps in ESXi.
•  Maximum of sixty Fibre Channel LUNs per ESXi system - ESXi allows a maximum of four SCSI controllers, each of which can support up to 15 SCSI devices.
Note: Block-disk LUN configuration pertains to Fibre Channel support. Fibre Channel is supported only in Core-v deployments. For details, see the SteelFusion Design Guide. For important distinctions between iSCSI and block-disk LUNs, see Block-disk LUN considerations.
To add a new LUN
1. Choose Configure > Manage: LUNs to display the LUNs page.
2. Click Add a LUN and configure it using the controls described in this table.
Control
Description
Add a LUN
Displays controls for adding a LUN to the current configuration.
iSCSI tab
Configure the iSCSI LUN with the following settings:
•  LUN Serial Number - Select from the drop-down list of discovered LUNs. The LUNs listed are shown using the following format: <serial-number>(<portal>/<target>). If the desired LUN does not appear in the drop-down list, click Rescan background storage for new LUNs.
•  LUN Alias - Specify an alias for the LUN.
•  IOPs Acceleration - Appears only if the Core is connected to a SteelHead EX or SteelFusion Edge model with a Solid State Disk (SSD) cache. Leverages the SSD read cache to improve input/output per second (IOPS) on the LUN. This option is enabled by default. Click Disable to disable it.
•  Add iSCSI LUN - Adds the new LUN to the running configuration.
Block Disk tab
Configure the block-disk LUN with the following settings:
•  LUN Serial Number - Select from the drop-down list of discovered LUNs. The LUNs are listed by their serial numbers. If the desired LUN does not appear in the drop-down list, click Rescan background storage for new LUNs.
•  LUN Alias - Specify an alias for the LUN.
•  Add Block Disk LUN - Adds the new LUN to the running configuration.
Additional steps are required before and after you configure a block-disk (Fibre Channel) LUN in the Core. For details, see Configuring branch recovery.
Edge Local tab
Configure the Edge Local LUN with the following settings:
•  SteelFusion Edge - Select a LUN from the drop-down list. This list displays configured Edges. For details, see Configuring Edges.
•  Size - Specify the LUN size in mebibytes (MiB), gibibytes (GiB), or tebibytes (TiB), as specified by the drop-down list.
•  Alias - Specify the alias for the LUN.
•  Add Local LUN - Adds the new LUN to the running configuration.
To configure a LUN
1. Click the LUN you want to configure.
2. Configure the LUN using the controls described in this table.
Control
Description
Details
Displays online or offline status:
•  Click Online to bring the LUN online.
•  Click Offline to take the LUN offline.
Note: The process of taking a LUN offline requires you first to power off the Windows server at the affected branch and then to unmount the LUN from ESX (if necessary). For details, see the SteelFusion Design Guide.
Displays the LUN alias, if applicable. Optionally, you can modify the value and click Update Alias.
Displays the following information about the LUN:
•  Connection Status
•  Accessibility (by iSCSI initiators at the Edge)
•  Snapshot Status
•  Locally Assigned LUN Serial
•  Origin LUN Serial
•  Origin Portal (Windows LUNs only)
•  Origin Target (Windows LUNs only)
•  Size
•  LUN I/O Report (links to report page)
Edge Mapping
Displays the target name and Edge to which the LUN is mapped.
•  To unmap, click Unmap.
Note: You must take the LUN offline before you can unmap it.
Failover
Displays whether the LUN is configured for failover.
•  To enable or disable failover, click Enable or Disable.
Note: LUN failover is in effect only when failover is also configured for the current Core. For details, see Configuring failover.
MPIO
(iSCSI LUNs only)
Applies the MPIO policy you select from the drop-down list:
•  Round-Robin - The Core uses multiple paths for read I/O on the LUN in a round-robin pattern: for example, 100 reads on path 1 followed by 100 reads on path 2, and so on. I/O writes still always use a single path.
•  Fixed-Path - The Core uses a single path for I/O on the LUN. This path is chosen from all the connected paths based on the priorities and preferences detailed above.
For the selected MPIO policy, the MPIO path table displays the following information about the iSCSI path to the backend:
•  Source Interface: The IP address and port on the Core.
•  Destination Interface: The IP address and port on the backend storage array.
•  For the Fixed Path policy, the Path Included check box: Select to include this path in the list of paths for I/O.
•  For the Fixed Path policy, the User Preferred button: Click to make this path preferred. Preferred paths receive higher priority.
•  Array Preferred: Whether the array indicates that the I/O initiator should prefer this path when available. If so, the Core gives this path higher priority.
•  Connected: network status of this path (connected or disconnected).
•  Status: MPIO status of this path, as reported by the array. The status can be:
–  Active Optimized: Active (I/O possible) and optimized (the best path for I/O).
–  Active Unoptimized: Active (I/O possible) but unoptimized (not the best path for IO).
Snapshots
Displays the following sets of controls for snapshot configuration:
•  History - Displays a detailed list of snapshots taken of the LUN.
•  Scheduler - Use the controls in this tab to apply snapshot schedule policies to the current LUN. For details see Applying a snapshot schedule policy to a LUN.
•  Configuration - Use the controls in this tab to enable and configure application-specific snapshots and data protection options.
Configure the following settings:
–  Storage Array or Handoff Host - For storage arrays from qualified vendors (Dell EqualLogic, EMC VNX, NetApp, HP 3PAR, IBM v7000, and IBM XIV/Spectrum Accelerate), specify Storage Array and select from the drop-down list the preconfigured array where the snapshot is stored. You can configure storage arrays for snapshots on the Configure > Backups: Snapshots page. For details, see Configuring snapshots for storage arrays.
–  For nonqualified storage arrays, specify the Handoff Host option and select the host from the drop-down list. You can configure handoff hosts for snapshots on the Configure > Backups: Snapshots page. For details, see Configuring handoff hosts.
After you specify the storage array or handoff host, click Update Settings to update the changes. You can also test the connection by clicking Test Storage Array.
–  Snapshots Static Name - Specify a string to be prepended to the names of snapshots taken of this LUN.
–  Storage Group / Host (EMC and IBM LUNs only) - Specify the storage group/host for the proxy backup server. This name is case sensitive and should be the same as the name you defined in the storage array.
Click Update Vendor-Specific Settings to update the changes.
–  Client Type - Select VMware, Windows, or Other. The type you select determines the settings in the Application Consistent Snapshots and Proxy Backup panels.
Click Update Client Type to update the changes.
For details about application-consistent snapshots and proxy backup configuration, see Configuring application-consistent snapshots for a LUN.
Note: To configure application-consistent snapshots and proxy backup settings for the current LUN, you must specify either VMware or Windows for the client type.
Pin/Prepop
Displays the pin status (Pinned or Unpinned) and provides controls for changing the status.
When a LUN is pinned, the data is reserved and not subject to the normal blockstore eviction policies. For details about pinning, see the SteelFusion Design Guide.
This tab also contains controls for enabling or disabling the prepopulation service and for configuring a prepopulation schedule.
Note: You can create a prepopulation schedule only when the pin status is set and updated to Pinned.
Branch Recovery
The Core displays the following controls for configuring branch recovery for the selected LUN. For details, see Configuring branch recovery.
•  Click Enable to enable branch recovery, or click Disable to disable it.
•  Click Change Schedule to set a date and time for the branch recovery operation.
–  From the scheduler, you can also select Now to start the operation immediately.
–  Click Submit Schedule to finalize the schedule.
–  Click Hide Scheduler to close the calendar controls.
•  Click Add VM to add one or more VMs to prepopulate for the operation.
–  From the drop-down list, select a VM, or select all.
–  Set the VM capacity percentage. This percentage is the maximum data capacity prepopulated by branch recovery per virtual disk.
•  After you have added a VM, you can remove it by clicking the X icon to the right and confirming the removal.
Note: The VM functionality does not apply to New Technology File System (NTFS) LUNs. For these LUNs, simply enable the operation and schedule it.