Information Technology Reference
In-Depth Information
File Server Concepts
A
file server
is a standalone system that functions as a server and allows clients
to access files via the network. There are several variations of file servers.
One important type of file server in the Solaris environment is the
operating
system (OS) server
. The OS server provides access to client systems that do
not have all or some of the operating system files available through local file
systems on local hard disks.
An OS server can support more than one version of an operating system at a
time. This includes not only different releases of an operating system, such
as Solaris 9, Solaris 8, Solaris 7, and SunOS 2.5, but also different hardware
platforms, such as SPARC and Intel x86 compatibles.
Diskless Configuration
A
diskless client
, as the name implies, does not have a hard disk for locally stor-
ing the operating system or applications. This storage is provided by a
disk-
less client server
that is accessible via the network. For a diskless client to boot
and operate, the client must remotely mount its root (
/
) and
/usr
file systems
from an OS server.
In addition to providing a common set of operating system files for all the
diskless clients (of the same version) through the network, the OS server pro-
vides hard disk space assigned for use by each client. This disk space is used
for swap space for the diskless client's virtual memory system and the
/home
file system for user accounts that are unique to each diskless client.
Compared to the standalone configuration, the diskless configuration is
cheaper and easier to maintain because only a very small number of systems
(the OS servers) require hard disks. Only one copy of common files is
required, and this is shared among many clients. In addition, all data unique
to each client is stored on an OS server, simplifying backup and restore pro-
cedures. Because no data is stored on the clients, the client hardware can be
easily replaced or upgraded.
The main disadvantages of the diskless configuration are its dependence
on the network and the load that it places on the network. If a diskless
client cannot access the OS server via the network, it cannot operate. In
addition, because all data (including that in swap space) is accessed
remotely, the network is extremely loaded even under normal operating
conditions.
