You there? Yes

Network Health Monitoring Heartbeats are sent to monitor health status of network interfaces Are sent over all cluster enabled networks Intra-cluster Communication Database updates and state synchronization that are sent between the nodes in the cluster Example: When creating a new resource the cluster database must be updated on all nodes Are over a single interface CSV I/O Redirection Metadata updates to files All I/O in failure scenarios Over same network as intra-cluster communication Over a single interface Can leverage SMB multi- channel to stream over multiple interfaces

Lightweight (only 134 bytes) Sensitive to latency If cluster heartbeats become blocked by a saturated NIC, this could cause nodes to be removed from cluster membership Bandwidth not important, but quality of service is Heartbeats Lightweight Traffic varies by workload, in general infrequent on running stable File / Hyper-V clusters. Heavier on SQL / Exchange clusters Clustering is a distributed synchronous system, latency will slow down cluster state changes (such as failover) Bandwidth not important, but quality of service is Intra-Cluster Communication Metadata updates Lightweight and Infrequent Latency will slow down I/O performance Yes, network performance will impact storage I/O performance! Quality of service most important Failure scenarios / asymmetric storage configurations All I/O is forwarded via SMB over the network Network bandwidth is most important CSV I/O Redirection

I can’t get through! Key Take-away: Primary design consideration for cluster communication is ensuring quality of service

Isolated network for the host partition Increased security isolation (could use VLAN’s to isolate from Client network) Host Management Public network for client access to VMs Virtual Machines Short duration heavy burst traffic Live Migration Intra-cluster communication is lightweight, but sensitive to latency Metadata updates are infrequent and light, but failure conditions could be heavy Intra-cluster communication / CSV Dedicated storage network Disable for cluster use iSCSI Key Takeaway: It is really about providing quality of service guarantees!!

Required? No – It is not required to have 2 separate networks Clustering does support a converged networking model Validate will generate a Warning to alert you of a potential single point of failure Validate is not NIC Teaming aware Recommended? Yes – It is recommended to have redundant network communication between nodes Sort of… let’s talk about what really matters and converged networking (next slide)

Resiliency

SAN Connectivity Failure SAN Connectivity Failure I/O Redirected via SMB VM running on Node 2 is unaffected SAN

Highest Availability Tolerance of Transient Failures

Increasing heartbeat thresholds does not fix network problems, it only masks them! PropertyDefaultMaximumDescription SameSubnetDelay1 second2 secondsFrequency heartbeats are sent SameSubnetThreshold5 heartbeats120 heartbeatsMissed heartbeats before an interface is considered down CrossSubnetDelay1 second4 secondsFrequency heartbeats are sent to nodes on dissimilar subnets CrossSubnetThreshold5 heartbeats120 heartbeatsMissed heartbeats before an interface is considered down to nodes on dissimilar subnets

Cluster PropertyDefaultHyper-V Default SameSubnetThreshold510 CrossSubnetThreshold520

NameValueDescription Disabled for Cluster Communication 0No cluster communication of any kind sent over this network Enabled for Cluster Communication only 1Internal cluster communication and CSV traffic can be sent over this network Enabled for client and cluster communication 3Cluster IP Address resources can be created on this network for clients to connect to. Internal and CSV traffic can be sent over this network

If enabled for iSCSI Software Initiator New Windows Server 2012 logic Disabled for Cluster Communication If no default gateway is present Enabled for Cluster Communication only If a default gateway is present Enabled for client and cluster communication

CSV Streaming I/O Across Multiple Networks X X

Prioritization Recommendation: Configure on all cluster deployments Heartbeats and Intra-cluster communication are sensitive to latency and configuring a QoS Priority Flow Control policy will ensure they are sent first Bandwidth Allocation Recommendation: Configure on CSV deployments CSV may send large amounts of data, need to ensure it has sufficient bandwidth Relative Minimum Bandwidth SMB policy recommended

Do not attempt to find cross subnet routes if local routes are found Always attempt to find routes that cross subnets Disable the cluster service from attempting to discover cross subnet routes after node successfully joins

OR Network Name Resource IP Address Resource A IP Address Resource B

DNS Server 1 DNS Server 2 DNS Replication Record Created Record Updated Site A Site B Record Updated Record Obtained

DNS Server 1 VM = Site ASite B

DNS Server 1 DNS Server 2 FS = Site ASite B VLAN

DNS Server 1 DNS Server 2 VM = Site ASite B

Site A Site B ValueDescription 0Clear Text 1Signed (default) 2Encrypted Disclaimer: Incurs some performance overhead

PropertyDescription ResourceDataResource Internal Use (read only) StatusNetBIOSStatus (error) code for NetBIOS – 0 means no error (read only) StatusDNSStatus (error) code for DNS – 0 means no error (read only) StatusKerberosStatus (error) code for Kerberos – 0 means no error (read only) CreatingDCDomain controller upon which this netname’s AD object was initially created (read only) LastDNSUpdateTimeTime at which DNS was last updated (read only) ObjectGUID(read only) NameThe name published in NetBIOS and SAM account name in AD DnsNameThe name published in DNS RemapPipeNamesLegacy setting for SMB HostRecordTTLTTL in seconds of the DNS record, this controls how long caches will retain the record RegisterAllProvidersIP0 (false), 1 (true) – when enabled all IP addresses this netname depends on will be published to DNS no matter what their provider state is PublishPTRRecords0 (false), 1 (true) – Create reverse DNS records TimerCallbackAdditionalThresholdUnused

PropertyDescription LeaseObtainedTimeTime when DHCP lease was acquired (Read only) LeaseExpiresTimeTime when DHCP lease runs out (Read only) DhcpServerThe DHCP server that issued the lease (Read only) DhcpAddressAddress assigned by DHCP (Read only) DhcpSubnetMaskSubnet mask assigned by (Read only) NetworkThe network this IP address is on (such as “Cluster Network 2”) AddressThe IP Address assigned to this IP resource SubnetMaskSubnet mask EnableNetBIOS0 (false), 1 (true) - Controls whether this address is published by netbios OverrideAddressMatchThis setting is unused EnableDhcp0 (false), 1 (true) – determines whether this IP Address resource obtains its address via DHCP