Configuring the iSCSI initiator
The iSCSI initiator settings dictate how the Core communicates with one or more storage arrays through the specified portal configuration. iSCSI configuration includes:
• Initiator name
• Enabling header or data digests (optional)
• Enabling CHAP authorization (optional)
• Enabling MPIO and standard routing for MPIO (optional)
Settings for iSCSI initiators, local interfaces for MPIO, portals, and targets are under Configure > Storage: iSCSI, Initiators, MPIO. Before you can configure LUNs in Core, you must provision the LUNs on the storage array and configure the iSCSI initiator.
Exposing LUNs
You expose LUNs by scanning for LUNs on the storage array, and then mapping them to the Edges. After exposing LUNs, you can further configure them for failover, MPIO, snapshots, and pinning and prepopulation.
In the Core Management Console, you can expose and configure LUNs by choosing Configure > Manage: LUNs. For more information, see the Core user guide.
In the Core CLI, you can expose and configure LUNs with the following commands:
• storage iscsi portal host rescan-luns discovers available LUNs on the storage array.
• storage lun add adds a specific LUN.
• storage lun modify modifies an existing LUN configuration.
Resizing LUNs
If you have configured Replication, the new LUN size on the primary Core is updated only when the replica LUN size is the same or greater.
The LUN expansion feature generally automatically detects LUN size increases made on a data center storage array if there are active read and write operations, and then propagates the change to the Edge. However, if there are no active read and write operations, you must perform a LUN rescan on the Core Configure > Manage: LUNs page for the Core to detect the new LUN size.
If the LUN is pinned, you need to make sure the blockstore on its Edge can accommodate the new size of the LUN.
Configuring Fibre Channel LUNs
The process of configuring Fibre Channel LUNs for Core requires configuration in both the ESXi server and the Core.
Offlining LUNs
When you take a LUN offline, outstanding data is flushed to the storage array LUN and the blockstore cache is cleared. This operation can take seconds to hours, depending on the WAN bandwidth, latency, utilization, and the amount of data in the Edge blockstore that has not yet been synchronized back to the data center.
Use the reports on the Edge to help understand just how much data is left to be written back. Until all the data is safely synchronized back to the LUN in the data center, the Core keeps the LUN in an offlining state. Only when the data is safe does the LUN status change to offline.
The settings for taking a LUN offline are under Configure > Manage: LUNs. Just select the LUN configuration in the list, and then select the Details tab. You can also use the storage lun modify offline command.