6.0 HP X9000 File Serving Software File System User Guide (TA768-96043, October 2011)

1 Using X9000 Software file systems
File system organization and access
The following diagram shows how data is organized on a file system and how it is accessed.
The diagram includes the following items:
1. The file system is a collection of segments (logical volumes) that organize data for faster access.
Each segment is a repository for files and directories with no implicit namespace relationships
among them. (A segment need not be a complete, rooted directory tree.) Segments can be of
any size, and different segments can be of different sizes. A file can span several segments
and multiple segments can be accessed in parallel within the same namespace.
2. The location of files and directories within segments is independent of their physical locations.
A directory can be located on one segment, while the files in that directory are spread over
other segments. Segments for new files and directories are selected dynamically according
to an allocation policy. This policy is set by the system administrator based on anticipated
access patterns and criteria such as performance and manageability.
3. File serving nodes, or servers, manage the individual segments of the file system. Each segment
is assigned to one server, and each server can “own” multiple segments, as shown by the
colors in the diagram. Segment ownership can be migrated from one server to another while
the file system is in use. When servers are added to the cluster, the ownership of existing
segments is distributed for proper load balancing and utilization by all servers. When storage
is added, ownership of the new segments is distributed among existing servers.
4. Clients run the applications that use the file system. Clients can access the file system either
as a locally mounted cluster file system using the X9000 client driver, or by using standard
NAS protocols such as NFS, CIFS, HTTP, and FTP. Based on the file or directory being
accessed, X9000 client requests are routed directly to the correct node. A client using NAS
File system organization and access 9