6.1 HP IBRIX X9000 Network Storage System File System User Guide (TA768-96061, June 2012)

17 Using file allocation
This chapter describes how to configure and manage file allocation.
Overview
X9000 Software allocates new files and directories to segments according to the allocation policy
and segment preferences that are in effect for a client. An allocation policy is an algorithm that
determines the segments that are selected when clients write to a file system.
File allocation policies
File allocation policies are set per file system on each file serving node and on X9000 clients. The
policies define the following:
• Preferred segments. The segments where a file serving node or X9000 client creates all new
files and directories.
• Allocation policy. The policy that a file serving node or X9000 client uses to choose segments
from its pool of preferred segments to create new files and directories.
The segment preferences and allocation policy are set locally for X9000 clients. For NFS, CIFS,
HTTP, and FTP clients (collectively referred to as NAS clients), the allocation policy and segment
preferences must be set on the file serving nodes from which the NAS clients access shares.
Segment preferences and allocation policies can be set and changed at any time, including when
the target file system is mounted and in use.
IMPORTANT: It is possible to set separate allocation policies for files and directories. However,
this feature is deprecated and should not be used unless you are directed to do so by HP support.
NOTE: X9000 clients access segments directly through the owning file serving node and do not
honor the file allocation policy set on file serving nodes.
IMPORTANT: Changing segment preferences and allocation policy will alter file system storage
behavior.
The following tables list standard and deprecated preference settings and allocation policies.
Overview 195