10Gbe Connectivity; Interface Speed And Duplex Settings; Flow Control - HP StoreVirtual 4000 White Paper

Technical white paper | HP StoreVirtual 4000 Storage
Figure 3 shows the speed, duplex, and frame size settings in the Centralized Management Console for an interface which
is not part of a bond. It is recommended to configure network settings on each storage node before joining these nodes
to a new or existing management group. When configuring network settings on a storage node after it has been added
to the management group and cluster, the storage node may become temporarily unavailable. All network configuration
changes need to be carefully planned; specifically if quorum or data availability depends on a single storage node. For
more information on quorum in management groups, refer to the HP StoreVirtual User Guide.

10GbE connectivity

10GbE network interfaces provide higher bandwidth than 1GbE adapters. To use 10GbE interfaces on HP StoreVirtual, the
LeftHand OS interface needs to be configured to the 10GbE interface bond on the storage node. All storage nodes in the
same HP StoreVirtual cluster should have the same connectivity to the network; i.e., mixing 10GbE and 1GbE interfaces
as the primary LeftHand OS interface on the same cluster is not a best practice configuration.
10GbE connectivity for iSCSI on HP StoreVirtual 4000 Storage makes sense for large sequential workloads, like
streaming, video editing, and large file operations (network-bound). Essentially, all workloads, which require high
sequential throughput per volume, benefit from 10GbE. In other cases where high number of I/O operations is required
(disk-bound), 1GbE is typically sufficient.
10GbE upgrade option for HP StoreVirtual 4000 Storage (and HP P4000 G2 Storage Systems) comes with 10GbE SFP+
SR optics, which work with standard OM3 cabling. Alternatively, direct-attach cables (DAC) may be used to connect HP
StoreVirtual 4000 Storage to the storage network.

Interface speed and duplex settings

The default interface speed and duplex mode for 1GbE interfaces on StoreVirtual is set to auto for both the speed and
mode of duplexing on storage systems. With auto/auto set, the speed and duplex setting are automatically negotiated
between interfaces on the storage node and switch ports. This setting should remain unchanged in most environments.
If auto-negotiation is not resulting in 1GbE on the storage nodes, this may be an indication that the switch ports are not
configured correctly or that the cabling is faulty. The default interface speed and duplex mode on HP StoreVirtual 4000
Storage with 10GbE network adapters are hard set to 10GbE and full duplex.
Best practices
• Set interfaces on HP StoreVirtual 4000 Storage and switch ports to auto negotiate, thus allowing the devices to auto
negotiate speed and duplex settings
• Verify that the speed and duplex of storage interfaces and switch ports match

Flow control

Flow control allows the receiver to instruct the sender to pause transmission of Ethernet traffic when the receiver
senses congestion or buffer cache pressure. The receiver accomplishes this by sending pause control frames to the
sender, which causes the sender to cease transmission for a brief period. This allows the receiving switch time to process
buffered cache. It is recommended to enable send and receive flow control on all edge ports handling iSCSI traffic. Some
switches will allow to configure flow control for receive (Rx), transmit (Tx), or both (Rx/Tx).
IP storage networks are unique in the amount of sustained bandwidth that is required to maintain adequate performance
levels under heavy workload. For HP StoreVirtual, flow control should be enabled on all appropriate servers, storage
systems, and switch ports. The default flow control setting on storage systems' network interfaces is auto-negotiate,
which is recommended by HP.
Best practices
• Set flow-control setting to auto-negotiate on storage systems which is the default (see figure 3).
• Enable flow control on all switch ports, which are used for iSCSI to achieve optimal performance.
• Set the desired flow control setting before you create the bond; modifying the flow control settings on bonded
interfaces is not possible without deleting the bond first.
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