Apple 95014-2084 User Manual download pdf (Page 19)

Chapter 1 Understanding System Imaging 19

For example, if you decide to store images on three server disks, NetBoot service sets

up three share points named NetBootSP0, NetBootSP1, and NetBootSP2.

The share points for client shadow files are also created in /Library/NetBoot/ and are

named NetBootClientsn.

You can create and enable NetBootSPn and NetBootClientsn share points on other

server volumes using the NetBoot service General settings in Server Admin.

Using NetBoot and NetInstall Images on Other Servers

You can also specify the path of a NetBoot image residing on a different NFS server.

When creating image files, you can specify which server the image will reside on. See

“Using Images Stored on Remote Servers” on page 53.

Client Information File

NetBoot service gathers information about a client the first time a client selects a

NetBoot or NetInstall volume to start from the Startup Disk. NetBoot service stores this

information in the /var/db/bsdpd_clients file.

Shadow Files

Many clients can read from the same NetBoot image, but when a client must write

back to its startup volume (such as print jobs and other temporary files), NetBoot

service redirects the written data to the client’s shadow files, which are separate from

regular system and application software.

Shadow files preserve the unique identity of each client while it is running from a

NetBoot image. NetBoot service transparently maintains changed user data in shadow

files while reading unchanged data from the shared system image. Shadow files are

recreated at startup, so changes made to a user’s startup volume are lost at restart.

For example, if a user saves a document to the startup volume, after a restart that

document will be gone. This behavior preserves the condition of the environment the

administrator set up. Therefore users must have accounts on a file server on the

network to save documents.

Balancing the Shadow File Load

NetBoot service creates an AFP share point on each server volume you specify (see

“Choosing Where Shadow Files Are Stored” on page 52) and distributes client shadow

files across them as a way of balancing the load for NetBoot clients. There is no

performance gain if the volumes are partitions on the same disk. See “Distributing

Shadow Files” on page 67.

WARNING: Don’t rename a NetBoot share point or the volume it resides on. Don’t

stop sharing a NetBoot share point unless you first deselect the share point for

images and shadow files in Server Admin.

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Apple 95014-2084 User Manual Page 19