HP StorageWorks X3000 Network Storage Systems - Manual (Page 52)

dynamic disks is unavailable. There could be a potential for data loss depending on the nature of the
failed LUN.
Volumes are created out of the dynamic disks, and can be expanded on the fly to extend over multiple
dynamic disks if they are spanned volumes. However, after a type of volume is selected, it cannot be
altered. For example, a spanning volume cannot be altered to a mirrored volume without deleting
and recreating the volume, unless it is a simple volume. Simple volumes can be mirrored or converted
to spanned volumes. Fault-tolerant disks cannot be extended. Therefore, selection of the volume type
is important. The same performance characteristics on numbers of reads and writes apply when using
fault-tolerant configurations, as is the case with controller-based RAID. These volumes can also be
assigned drive letters or be mounted as mount points off existing drive letters.
The administrator should carefully consider how the volumes will be carved up and what groups or
applications will be using them. For example, putting several storage-intensive applications or groups
into the same dynamic disk set would not be efficient. These applications or groups would be better
served by being divided up into separate dynamic disks, which could then grow as their space
requirements increased, within the allowable growth limits.
NOTE:
Dynamic disks cannot be used for clustering configurations because Microsoft Cluster only supports
basic disks.
File system elements
File system elements are composed of the folders and subfolders that are created under each logical
storage element (partitions, logical disks, and volumes). Folders are used to further subdivide the
available file system, providing another level of granularity for management of the information space.
Each of these folders can contain separate permissions and share names that can be used for network
access. Folders can be created for individual users, groups, projects, and so on.
File sharing elements
The storage system supports several file sharing protocols, including Distributed File System (DFS),
Network File System (NFS), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), and
Microsoft Server Message Block (SMB). On each folder or logical storage element, different file sharing
protocols can be enabled using specific network names for access across a network to a variety of
clients. Permissions can then be granted to those shares based on users or groups of users in each of
the file sharing protocols.
Volume Shadow Copy Service overview
The Volume Shadow Copy Service (VSS) provides an infrastructure for creating point-in-time snapshots
(shadow copies) of volumes. VSS supports 64 shadow copies per volume.
Shadow Copies of Shared Folders resides within this infrastructure, and helps alleviate data loss by
creating shadow copies of files or folders that are stored on network file shares at pre-determined
time intervals. In essence, a shadow copy is a previous version of the file or folder at a specific point
in time.
By using shadow copies, a storage system can maintain a set of previous versions of all files on the
selected volumes. End users access the file or folder by using a separate client add-on program, which
enables them to view the file in Windows Explorer.
Storage management overview 52