Novell Cluster Services alone does not provide load-balancing services between nodes in the cluster. Load-balancing cluster solutions require cluster-aware applications or additional external hardware. Because Novell iFolder 2.1 is not a cluster-aware application, a load-balancing solution based on NetWare and the server hardware alone is not possible. Only one server in the cluster operates at any given time.
An active/passive, two-node cluster is the basic fault-tolerant, high-availability solution. You can add multiple passive (standby) servers, if desired, for increased availability. In an active/passive cluster configuration, one server is active and any other nodes serve as a standby servers. If the active server goes down, the Novell Cluster Services software handles the graceful failover to the next available server in the cluster.
The failover is transparent to users logged in to iFolder server accounts from the iFolder clients. Users logged in to the iFolder server via a Web browser might need to click Refresh to reactivate the link to the server.
A Novell Cluster Services solution requires a storage-area-network (SAN) configuration to support the sharing of devices between multiple member nodes of the cluster. It is also possible to configure a two-node cluster, using two servers connected to a single external storage array, but this solution does not offer the same type of connection fault tolerance as a SAN.
In a shared-disk cluster, a single disk error can cause a volume failure if fault-tolerant measures are not used. Novell Cluster Services does not protect against disk and connection faults.
To add fault tolerance against a single disk failure to the
shared-disk system, you can set up the devices you plan to use in
the cluster as software RAID 1 (mirrored) devices or as software
RAID 5 (striping with parity) devices. Make the software RAID devices
sharable for clustering, then assign them as devices in the cluster-enabled
pool. For information, see Using
Software RAID Devices to Enhance Data Fault Tolerance and Performance
in
the Novell
Storage Services Administration Guide for NetWare 6.5.
To add fault tolerance against a connection failure, NetWare
supports multipath I/O to your storage devices. You can
specify which path to use as the primary path between the server
and the device for each member server, then specify the failover
priority for other paths. For information, see Managing
Multiple Connection Paths to Devices (NetWare)
in
the Novell
Storage Services Administration Guide for NetWare 6.5.
In Novell iFolder 2.1 and later, iFolder runs as a module on Apache. Any failure of the module causes the Apache instance to fail. This means that if you run multiple applications in a single instance of Apache, all the applications fail if one application module fails.
If you plan to run other applications that use Apache on a clustered server, we recommend that you install Novell iFolder first in its own instance of Apache. For information on setting up additional instances of Apache on a server, consult the Apache Web site.
As discussed in Section 3.0, Preparing to Install iFolder 2.1, you must install and configure at least one LDAP server before you install Novell iFolder. The LDAP server must be in the same local tree as the iFolder server. Although you can point iFolder to the master LDAP server or a replica, we recommend you point to the master LDAP server.
During the installation of iFolder on the primary server, you identify the primary LDAP server that the iFolder cluster uses. You specify the LDAP server's address during the iFolder installation. If you change the LDAP server address later, you must change it in the iFolder configuration. After the cluster configuration is complete, you can add additional LDAP servers to the list to ensure fault tolerance. For information, see Managing User LDAP Servers.
The LDAP service must always be available to iFolder in the event of failover. Typically, the LDAP server can be the same server as the iFolder server. However, in a clustered iFolder configuration, the LDAP server should not reside on any of the member nodes in the cluster. For example, if you put the LDAP server on the primary server and that server failed over, then the LDAP services would no longer be available to a standby server that becomes active. To ensure that the LDAP service is available to any of the nodes that might become active, put your LDAP service on a server other than the servers in the cluster, then point iFolder to it.
If you decide to place an LDAP server replica on every member node, the primary iFolder server must be the one that the install points to as the LDAP server. After the cluster install, you need to perform the following steps:
With the designated primary server active, use the iFolder Management Console to set up the additional replicas as alternatives to be used in the event of server failover:
Edit the iFolder apache conf file and replace LdapHost IP address with LdapHost 127.0.0.1 (This will point to localhost incase of cluster failover).
Restart the iFolder server.