Quantum 6-01376-05 manual Network Configuration and Topology

Network Configuration and Topology

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The Distributed LAN (Disk Proxy) Networks

Acommon source of difficult-to-diagnose issues with SNFS is improper IP network configuration. Many incorrect IP configurations might appear to work when tested with particular applications or particular kinds of hosts, but fail when used with SNFS or when a different kind of host is added to the cluster.

SNFS Distributed LAN should be run over one or more dedicated IP subnetworks, using dedicated NICs for each subnetwork. These subnetworks are typically configured using site-local addresses, such as 10.a.b.c or 192.168.x.y.

For example, if SNFS Distributed LAN is set up to use two Gigabit Ethernet NICs (for a total bandwidth of 2 Gbits/s for Distributed LAN I/O), each Distributed LAN Server and Distributed LAN Client should have at least 4 NICs: 2 dedicated NICs for Distributed LAN, 1 dedicated NIC for SNFS Metadata traffic, and 1 NIC for administrative access and other traffic. Each of the NICs must be configured for a separate IP subnet. So for example, if the subnets chosen for Distributed LAN are 192.168.1.0/24 and 192.168.2.0/24, each Distributed LAN Server and each Distributed LAN Client must have one (and only one) NIC with an IP address of 192.168.1.x, plus one (and only one) NIC with an IP address of 192.168.2.y.

It is best practice to have all of the NICs for the same Distributed LAN subnetwork directly connected to the same network switch. A router between a Distributed LAN client and server could be easily overwhelmed by the data rates required.

By contrast, Quantum recommends having the NICs for different Distributed LAN subnetworks connected to different network switches, to avoid overwhelming any one network switch.

All Distributed LAN subnetworks must be completely connected. This typically means all Distributed LAN clients and all Distributed LAN servers have dedicated NICs for each of the Distributed LAN subnetworks. If a Distributed LAN client does not have a dedicated NIC for a particular Distributed LAN subnetwork, it must be configured with static routes to give it connectivity to each of the IP addresses advertised by the Distributed LAN servers. Note that if a Distributed LAN client is unable to connect to a particular server’s NIC, it will continue forever trying to connect to it, potentially causing slow file system mounts, repeated messages in error logs, and other problems.

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