Application Considerations - IBM N Series Hardware Manual

14.2.7 Application considerations

Different applications and environments put different workloads on the storage system. This
section addresses a few considerations that are best addressed early in the planning and
installation phases.
Home directories and desktop serving
This is a traditional application for network-attached storage solutions. Because many clients
are attached to one or more servers, there is little possibility to effectively plan and model in
advance of actual deployment. But a few common sense considerations can help:
This environment is generally characterized by the use of Network File System (NFS) or
Common Internet File System (CIFS) protocols.
It is generally accessed by using Ethernet with TCP/IP as the primary access mechanism.
The mix of reading and writing is heavily tipped towards the reading side. Uptime
requirements are generally less than those for enterprise application situations, so
scheduling downtime for maintenance is not too difficult.
In this environment, the requirements for redundancy and maximum uptime are sometimes
reduced. The importance of data writing throughput is also lessened. More important is the
protection offered by Snapshot facilities to protect user data and provide for rapid recovery in
case of accidental deletion or corruption. For example, email viruses can disrupt this type of
environment more readily than an environment that serves applications like Oracle or SAP.
Load balancing in this environment often takes the form of moving specific home directories
from one storage system to another, or moving client systems from one subnet to another.
Effective prior planning is difficult. The best planning takes into account that the production
environment is dynamic, and therefore flexibility is key.
It is especially important in this environment to install with maximum flexibility in mind from the
beginning. This environment also tends to use many Snapshot images to maximize the
protection offered to the user.
Enterprise applications
Previously the domain of direct-attached storage (DAS) architectures, it is becoming much
more common to deploy enterprise applications that use SAN or NAS storage systems.
These environments have significantly different requirements than the home directory
environment. It is common for the emphasis to be on performance, uptime, and backup rather
than on flexibility and individual file recovery.
Commonly, these environments use a block protocol such as iSCSI or FCP because they
mimic DAS more closely than NAS technologies. However, increasingly the advantages and
flexibility provided by NAS solutions have been drawing more attention. Rather than being
designed to serve individual files, the configuration focuses on LUNs or the use of files as
though they were LUNs. An example would be a database application that uses files for its
storage instead of LUNs. At its most fundamental, the database application does not treat I/O
to files any differently than it does to LUNs. This configuration allows you to choose the
deployment that provides the combination of flexibility and performance required.
Enterprise environments are usually deployed with their storage systems clustered. This
configuration minimizes the possibility of a service outage caused by a failure of the storage
appliance. In clustered environments, there is always the opportunity to spread workload
across at least two active storage systems. Therefore, getting good throughput for the
enterprise application is generally not difficult.
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IBM System Storage N series Hardware Guide