3.7.0 HP StorageWorks HP Scalable NAS File Serving Software provisioning guide for Oracle HP Scalable NAS (AG513-96013, October 2009)

according to the requirements of the database. No more interaction is needed with
the system or storage administration groups. Contrast this to the amount of system
administrative overhead when deploying Oracle databases on raw partitions (or
even filesystems) in a SAN.
When one provisions storage using simple raw datafiles, or ASM or even iSCSI,
there is a significant amount of administrative overhead. First, the database
administrator has to determine the list of singleton LUNs needed, such as the Oracle
clusterware files, raw datafiles or ASM disk group partitions. The system administrator
then requests these LUNs from the storage group and proceeds to work out
connectivity, dealing with such issues as loading host bus adaptors, getting the LUNs
presented as character special raw devices, permissions, and in the case of Linux,
raw(8) binding and/or ASMLib configuration. This activity is much more complex
than simply mounting ready-made filesystems. Furthermore, in the case of direct attach
storage, should it be necessary to move the application to another server, the
provisioning must happen all over again.
With the NAS model, deploying RAC is much simpler for the DBA than using the
typical SAN deployment model. With NAS, the DBA is simply notified when the
filesystem is mounted and work can begin. The DBA can store everything associated
with the Oracle database in the NFS filesystems and all RAC servers have complete,
immediate, shared read/write access. Even Oracle home and, for Linux Oracle
servers, CRS voting and registry files can be shared, saving space and easing the
administrative overhead.
Therein, however, lies potential performance bottleneck and availability concerns.
What happens if the server or network fails? What happens when the server or
network becomes a performance bottleneck? The technology HP Scalable NAS uses
to address the inherent difficulties with network attached storage is this: Symmetrical
multi-headed NAS.
Symmetrical multi-headed NAS
To understand symmetrical multi-headed NAS, one must first understand the truly
revolutionary, highly available, scalable NFS server implementation that HP Scalable
NAS provides.
The HP Scalable NAS and HP FS Option for Linux software is installed on a cluster
of servers, allowing each server to export any filesystem found in the cluster. Each
server in the cluster (that is, each NAS server head) can present Export Groups
consisting of any filesystem in the cluster. All NFS Export Groups are presented to
NFS clients via a Virtual NFS Service (or VNFS). A VNFS is a combination of a Virtual
Host IP address and a proprietary enhancement to the NFS Server stack to support
completely transparent NFS client failover. During VNFS service transitions from one
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