Optimizing Your Print Environment with the HP Print Server Appliance

white paper HP Print Server Appliance 4250 July 2003 Optimizing Your Print Environment with the HP Print Server Appliance (PSA Firmware version 2.4...
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HP Print Server Appliance 4250

July 2003

Optimizing Your Print Environment with the HP Print Server Appliance (PSA Firmware version 2.4.x and above)

Overview The HP Print Server Appliance 4250 (PSA) offers the enterprise a simple, reliable, and cost effective print solution. It is important to understand how best to deploy the PSA to realize its maximum benefit. Optimizing performance of the PSA within a network environment is primarily affected by two variables: placement within the network, and printer-user load. While it would be useful to have some simple equation to determine the number and deployment strategy for your PSA printing solution, each environment is unique and will require a different balance of this solution. This paper offers general guidelines and suggestions that will help you determine how to best deploy the PSA within your print environment.

Description of the HP Print Server Appliance The PSA is a network device used to manage and monitor printing (Figure 1). It has been designed to provide a quick and easy way to add print capacity and off-load print spooling and services from the general-purpose servers.

Figure 1 – HP Print Server Appliance 4250

Optimizing within a Network Topology Though the PSA print solution will replace the function of your general print server(s), it is deployed under a localized print model rather than the centralized print model commonly used by general purpose servers. Under a centralized print model all print traffic must travel to a central server and then to a given printer. Thus every print job is competing with all other network activities for bandwidth and processing time. Under a centralized print model the printing functionality of your network is also more vulnerable to single point failures (Figure 2).

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Figure 2 – Centralized Print Model

In a localized printer model, print traffic is contained within a segment of the network. Through this localized print model the PSA off-loads general-purpose servers and optimizes the business’ network by eliminating print traffic from the WAN and/or backbone (Figures 3 and 4). This localized print model eliminates the single point of failure that exists within the centralized print model and provides a natural mechanism to optimize individual network segments for better performance and/or redundancy.

Figure 3 – Localized Print Model

PSA 4250 Opmtimizing Print Environments © Copyright Hewlett-Packard Company 2003

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Figure 4 – Localized Print Model (Remote Office)

Even if your network segments are large you can keep traffic localized and off the network backbone or WAN by hosting the PSA off of a top-of-stack switch (Figure 5).

Figure 5 – Top-of-Stack PSA Deployment

To summarize, consider the following key benefits: 1. Deploying the PSA in a localized print model provides radical simplicity. • Simple, single point for remote administration • Closed and contained system makes setup, management, and maintenance easy 2. Distributing printing functionality throughout the network increases reliability. • More effective business critical failure and recovery strategies • More print performance control for specified network segments • Distributed print functionality resulting in no single point of failure 3. Moving printing off the network backbone lowers the total cost of ownership. • Cost effective print model for remote offices • Reduced WAN cost • Backbone and/or general network bandwidth is freed from print traffic • General-purpose server processing is freed • Minimized business disruption due to printing

PSA 4250 Opmtimizing Print Environments © Copyright Hewlett-Packard Company 2003

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Note:

If domain authentication has been enabled, there will be communication between the PSA and system domain controllers. This means that though all print job traffic will be contained within a local network segment, print authentication traffic will not be if the domain controller is outside that segment. Due to this dependency, a slow authentication link may result in slower print performance.

Optimizing Print Performance Every print environment is unique; the actual load of printers, users, and jobs that can be handled optimally will vary. Variables that will affect actual print performance include: • • • • •

Type and size of print jobs Frequency of printing Network bandwidth Printer throughput Number of printers

Performance of the PSA is ultimately a function of its throughput. Print jobs are sent to a PSA; and then forwarded onto the appropriate printer(s). The rate at which the PSA can pass incoming print data to some destination printer is fixed. To better visualize this, consider the PSA print spooler as a funnel. Throughput of the PSA is bounded just as the throughput of any funnel is bounded by the width of the funnel (Figure 6). Although the maximum throughput of the PSA is fixed, if the amount of print data entering the PSA exceeds the amount of data leaving the PSA the entering data is temporarily stored. These print jobs are buffered within the PSA spool system until they can be printed. In these cases the PSA will operate smoothly at a maximum throughput but performance may not be optimal. To optimize performance we need to minimize the buffering that takes place on the PSA print spooler. This is accomplished by insuring that the PSA has an appropriate load or balance of printers and users based on the above mentioned print environment performance variables.

Figure 6 – The PSA Spooler as a Funnel

PSA 4250 Opmtimizing Print Environments © Copyright Hewlett-Packard Company 2003

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The recommended number of printers and users for a PSA is 50 and 350, respectively. This recommendation should be considered the upper bound for a typical general office environment. While it is helpful to have simple numbers like this as guidelines, real numbers are dependent on the actual user environment. To maximize PSA performance within a printing environment, additional PSAs may be desired. Print environments with any of the following characteristics indicate a potential for such load balancing: • • • •

High frequency printing Print jobs with a lot of graphics Print jobs with a lot of pages Low throughput printers such as legacy printers or plotters

There are several ways to decrease the load of a given PSA in a print environment with these characteristics. Consider reducing both the number of printers and users for a given PSA (Figure 7). This will naturally reduce the amount of print data that must be processed by the PSA at a given time and will ensure that data buffering is minimal.

Figure 7 – Reducing Printers and Users per PSA

You can also consider introducing an additional PSA to manage some of the printers on an overloaded PSA but maintaining the same number of users for both units (Figure 8). Reducing the number of users per PSA (but maintaining the number of printers) can also be considered.

Figure 8 – Reducing Printers per PSA

PSA 4250 Opmtimizing Print Environments © Copyright Hewlett-Packard Company 2003

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Summary Proper deployment of the PSA, with adherence to the guidelines discussed here, will result in a simple, reliable and low cost of ownership print solution. Please see you HP sales representative or contact HP support through www.hp.com if you have any questions regarding PSA deployment within your environment.

For More Information http://www.hp.com/support/printappliance http://www.hp.com/go/psa_whitepapers http://www.hp.com/go/wja_whitepapers

PSA 4250 Opmtimizing Print Environments © Copyright Hewlett-Packard Company 2003

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