Chapter 2. Software Layers

Chapter 2. Software Layers
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A FailSafe system has the following software layers:

Plug-ins, which create highly available services. Table 2-1, and Table 2-2, show the provided and optional FailSafe plug-ins and their associated resource types.

See the release notes for information about the specific releases of these products that are supported.

Note: The Samba interfaces parameter allows Samba to support multiple IP interfaces. It takes the following format, where IP must be a dotted decimal IP address and netmask must be a dotted decimal netmask such as 255.255.255.0:

interfaces = IP1/netmask1 IP2/netmask2

If the application you want is not available, you can hire the SGI Professional Services group to develop the required software, or you can use the FailSafe Programmer's Guide for SGI Infinite Storage to write the software yourself.

FailSafe base, which includes the ability to define resource groups and failover policies.
Cluster services, which lets you define clusters, resources, and resource types (this consists of the cluster_services installation package)
Cluster software infrastructure, which lets you do the following:
- Perform node logging
- Administer the cluster
- Define nodes
The cluster software infrastructure consists of the cluster_admin and cluster_control subsystems.

Table 2-1. Provided Plug-Ins

Provided Plug-In	Resource Type
CXFS file system	`CXFS`
IP addresses	`IP_address`
MAC addresses	`MAC_address`
XFS filesystems	`filesystem`
XLV logical volumes	`volume`
XVM volume manager	`XVM`

Table 2-2. Optional Plug-Ins

Optional Plug-In	Resource Type
FailSafe for DMF	`DMF`
FailSafe for NFS	`NFS` and `statd_unlimited`
FailSafe for Informix	`INFORMIX_DB`
FailSafe for Oracle	`Oracle_DB`
FailSafe for Samba	`Samba`
FailSafe for TMF	`TMF`
FailSafe for Web (Netscape)	`Netscape_web`

Figure 2-1 shows a graphic representation of these layers. The cluster services and cluster software infrastructure layers are shared with CXFS. Table 2-3, describes the contents of the /usr/cluster/bin directory. For more information about CXFS, see the CXFS Administration Guide for SGI Infinite Storage.

Figure 2-1. Software Layers

Table 2-3. Contents of /usr/cluster/bin

Layer	Subsystem	Process	Description
Plug-ins	`failsafe_informix` `failsafe2_oracle`	`ha_ifmx2`	FailSafe database agents. Each database agent monitors all instances of one type of database.
FailSafe Base	`failsafe2`	`ha_fsd`	FailSafe daemon. Provides basic component of the FailSafe software.
Cluster services (high-availability processes)	`cluster_services`	`ha_cmsd`	The FailSafe membership daemon. Provides the list of nodes, called FailSafe membership, available to the cluster.
		`ha_gcd`	Group membership daemon. Provides group membership and reliable communication services in the presence of failures to FailSafe processes.
		`ha_srmd`	System resource manager daemon. Manages resources, resource groups, and resource types. Executes action scripts for resources.
		`ha_ifd`	Interface agent daemon. Monitors the local node's network interfaces.
Cluster software infrastructure (cluster administrative processes)	`cluster_admin`	`cad`	Cluster administration daemon. Provides administration services.
	`cluster_control`	`crsd`	Node control daemon. Monitors the serial connection to other nodes. Has the ability to reset other nodes.
		`cmond`	Daemon that manages all other daemons. This process starts other processes in all nodes in the cluster and restarts them on failures.
		`fs2d`	Manages the cluster database and keeps each copy in sync on all nodes in the pool.

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