Diskless node

In many universities and in some large organizations, PCs are used in a similar configuration, with some or all applications stored remotely but executed locally—again, for manageability reasons.

In some cases, removable storage may be used to initiate the bootstrap process, such as a USB flash drive, or other bootable media such as a floppy disk, CD or DVD.

However, the firmware in many modern computers can be configured to locate a server and begin the bootup process automatically, without the need to insert bootable media.

Diskless network booting is commonly a built-in feature of desktop and laptop PCs intended for business use, since it can be used on an otherwise disk-booted standard desktop computer to remotely run diagnostics, to install software, or to apply a disk image to the local hard drive.

This third approach makes it easier to use client OS than having a complete disk image in RAM or using a read-only file system.

When volatile, all the data that has been written by a specific client to the virtual disk are dismissed when said client is rebooted, and yet, user data can remain persistent if recorded in user (roaming) profiles or home folders (that are stored on remote servers).

The two major commercial products (the one from Hewlett-Packard, and the other one from Citrix Systems) that allow the deployment of Diskless Nodes that can boot Microsoft Windows or Linux client OS use such write caches.

This allows use in public access areas (such as libraries) or in schools etc., where users might wish to experiment or attempt to "hack" the system.

However, this can be mitigated by installing large amounts of RAM on the server (which speeds up read operations by improving caching performance), by adding more servers (which distributes the I/O workload), or by adding more disks to a RAID array (which distributes the physical I/O workload).

In any case this is also a problem which can affect any client-server network to some extent, since, of course, fat clients also use servers to store user data.

Indeed, user data may be much more significant in size and may be accessed far more frequently than operating systems and programs in some environments, so moving to a diskless model will not necessarily cause a noticeable degradation in performance.