Allocate Your Workstation Budget According to Your Workload3 Sep, 2014 By: Alex Shows
Uncertain about how best to spend your hardware dollars? A careful evaluation of the type of work to be done — and these guidelines — will provide the answers.
Storage for Various Use Cases
A variety of storage performance considerations depend completely on the usage model. For instance, is the data stored on the network or stored locally on the workstation? If the former, how frequently are updates committed to the network resource? If the latter, how much capacity is required locally? Is redundancy required on the local storage? All of these factors are important to determining the right storage components for the workstation, and due to this complexity the subject deserves much greater attention than given here.
For simplicity, we’ll assume the data is stored locally on the workstation and not concern ourselves with network bandwidth, frequency of updates, or check-in/check-out procedures. A single user of the workstation will have a blend of three common local storage use cases:
- “Office Productivity” — reading and writing small files with occasional large file transfers (common activities for a project manager, design reviewer, or approver).
- “Interactive Workstation” — opening and saving a wide variety of file sizes (frequent tasks for a 2D or 3D drafter).
- “Computational Workstation” — iterating across very large sets of data, often generating large temporary files (such as an engineer using 3D rendering, simulation, and analysis packages).
Optimizing for the Office Productivity use case is usually as simple as weighing anticipated capacity needs with the highest-performing drive class within the budget. While rotational drives have traditionally dominated this segment, in recent years the decreasing cost of MLC (multilevel cell) memory and controllers has brought the more favorable solid-state drives (SSDs) and hybrid drives within reach of more users. In general, for this use case, hybrids provide the best price-to-performance ratio, while SSDs provide the best outright performance. Hybrids store the most commonly used data in cache, which is faster to access than the rotating media in the drive, and as long as the files are relatively small they’ll all fit nicely.
The Interactive Workstation usage model requires greater performance, and this is where solid-state disks (SSDs), serial-attached SCSI (SAS) drives, and redundant array of independent disk (RAID) arrays begin to play a more important role. If a single SSD provides the capacity needs of both your office productivity and interactive workstation usages, this option will perform best, second only to a multidrive RAID 0 array.
RAID arrays enable the creation of a large virtual drive that spans one or more physical (or logical) drives. Depending on the RAID type, new features such as redundancy (having more than one copy of the data simultaneously) and greater performance are possible. If redundancy is equally or more important than performance, having a RAID array such as a RAID 1, 10, or 5 would be the better choice. Then it becomes a decision between available (matching) drives to build the array. Moving to a RAID array can increase storage costs considerably, making it prohibitive to include high-performing drives in the array. One way to mitigate this cost while maintaining high performance is to use an SSD boot drive that hosts the operating system and applications, while building a RAID array out of lower-cost rotational disk drives.
For the computational workstation wherein significantly large datasets are used, the only option for this type of usage may be a RAID array composed of large drives. By combining the smaller-capacity drives into a single large volume, the application can use all of this capacity as if it were a single large drive. Multiple drives in RAID 0 will maximize performance and capacity, but this provides no redundancy. Multiple drives in RAID 1 provide redundancy but don’t maximize performance or capacity. RAID 10 increases performance and capacity and adds redundancy, but is the most costly in terms of the number of drives required.
Between RAID 0 and RAID 10 is RAID 5, which increases performance and capacity and adds redundancy with fewer drives than a RAID 10, but requires more overhead to manage the array due to the computation of parity data, which is then distributed across the array. When considering whether to add a fourth drive to an integrated storage controller and creating a RAID 10, consider the option to upgrade to a discrete RAID controller with onboard memory and moving to RAID 5. You’re likely to see higher capacity, and the benefits of a discrete RAID controller may mean higher performance in office productivity and interactive workstation usages, not to mention benefits to computational workstation usage types.
The Advantage of Application Certification
One of the key differentiators of professional workstations, as compared with conventional PCs, is the platform certifications to run specific professional workstation applications. Considering the complexity of the software environment, one can imagine the incredible number of variations that might exist in operating system versions, application versions, hardware, firmware, and driver versions. All of these variables can have an effect on application stability and performance. Workstation certification addresses this by being prescriptive about the components and revisions tested and found to be compatible with the application. This mitigates the risk to users when purchasing a new workstation or upgrading an existing workstation, as they can be confident before purchasing that the workstation in question has been certified by the software vendor of their desired application.
To find the right workstation configuration, first identify the primary and any secondary or tertiary usage models.
For interactive usage models, focus on maximizing CPU frequency, followed by the class of graphics. For individual CPU models, choose the latest architecture and look primarily at the peak Turbo frequency. Of the available CPU models, determine the best frequency for the price. Then look to graphics and compare frames per second using industry-standard benchmarks such as SPECviewperf, focusing on the applications and/or rendering modes that are most important to your usage. Judge which of the available GPU models offers the best frames per second for the price. Then look to memory and maximize memory bandwidth at the capacity desired. And finally, look to storage, where a single SSD might address all the interactive usage model needs, unless capacity or redundancy requires a RAID array, or spending limits dictate a single rotational disk drive.
For computational usage models, focus on maximizing core count, followed by CPU frequency. For individual CPU models, choose the latest architecture and look primarily at the lowest Turbo frequency (which reflects the lowest frequency the CPU will Turbo up to under heavy load). Look for the best core count per dollar, and if the workstation will spend more than half of its life in computational work, consider upgrading to a dual-socket workstation. If the application supports GPU compute, consider upgrading the GPU to models with more compute cores, as the performance per dollar in GPU upgrades will often be higher than the CPU (here again based on the percentage increase in core count). Upgrade memory by populating as many slots as possible first; except for a limited set of applications which are highly sensitive to latency, it is always best to upgrade to the fastest memory speed for the maximum possible computational throughput. Finally, consider the storage requirements primarily in terms of capacity and bandwidth required by the application, which is often much larger and higher than with other usage models.
Optimal performance for a particular usage model can be achieved by identifying the factors that are most important to that application: those having the highest impact on performance. Combining those selections in a workstation certified for operation with the key applications of that usage model will ensure that the user has the best experience possible.