An extra depth chassis is not always required, though.Workarounds can be implemented in order to fit an extra depth chassis into a regular depth cabinet, but an uncommon cabinet configuration would be required.

Common Extra Depth Systems

Some common extra depth systems are described in Table 1.All of the systems described in the table are GPU systems, having socketed or PCIe Tesla GPUs.

Table 1. Common extra depth systems

Commonly used extra depth cabinets are described in Table 2, ranging in height from 42U to 48U. Extra depth cabinets are the easiest solution for rackmounting extra depth systems.There are workarounds, however, which can be implemented for instances where a customer already has a regular depth cabinet on-site, and would prefer to use the existing cabinet, due possibly, to scarcity of unused floor space.

Table 2. Common extra depth cabinets

Workarounds Solutions

Workaround solutions for mounting extra depth systems into regular depth cabinets require extra considerations and conditions.

Workaround Solution #1: Remove any vertical PDUs, and replace them with horizontal PDUs

An extra depth system would be obstructed by full height vertical, “zero U”, PDUs, as it is slid toward the back of the cabinet, preventing it from sliding fully into the cabinet.All full height vertical PDUs must be removed from the cabinet, and replaced with horizontal PDUs.Because extra depth systems usually have a secondary system board, with socketed GPUs, they are usually power-dense.The NVIDIA DGX-1 GPU-accelerated system for deep learning, for example, requires 3.5kW of power, at peak workload.Tri-phase power is recommended, whenever possible, for power-dense GPU systems.With some power-dense configurations, it will not be possible to meet peak power requirements with single-phase power.

Along with their unusually high power density, extra depth systems will require high airflow.Using the NVIDIA DGX-1 again as an example, four chassis fans will each produce a maximum of 340 CFM of air flow, for a total of 1,360 CFM.For groups of systems having high air flow requirements, the cabinet doors must be perforated.

Selecting a tri-phase horizontal PDU can be a challenge, since they do not present as many outlets as vertically mounted PDUs, and will sometimes present an outlet type which is not compatible with the inlet type on the system(s).If the entire cabinet will not be needed for mounting extra depth systems, then using a half height PDU, possibly in addition to a horizontal PDU, may be a good choice.

APC currently offers only one tri-phase horizontal PDU. Geist offers a wide variety of tri-phase horizontal PDU types.These can be searched using the Geist PDU finder. Geist does not offer a tri-phase PDU, for use with a 208V, 20Amp source.However, it offers a variety of horizontal, tri-phase PDUs, for lines carrying 30Amps, or more.Like Geist, Server Technology offers a range of tri-phase, horizontal PDUs.They offer a tri-phase PDU model which can be used with a 208V, 20Amp power source, compatible with the NEMA L21-20P plug type.

Workaround Solution #2: Replace any full height vertical PDUs with half height PDUs

Half height PDUs are typically used for shorter cabinets.But they can also be used in regular height cabinets, to allow for installation of one or more extra depth system chassis.If the power receptacle is below the floor, then it will be easier to mount the PDU under the extra depth system(s), with the plug pointed downward.If the power receptacle is on the ceiling, then it will be easier to mount the PDU above the extra depth system(s), with the plug pointed upward.

Half height vertical PDUs should only be used if the entire cabinet will not be needed for mounting extra depth systems.This is because half height vertical PDUs will still prevent installation of extra depth systems into approximately half of the cabinet’s rackspace.Some half height PDUs can be mounted on the exterior of the cabinet frame, so that they will not obstruct extra depth systems from being rackmounted.

Figure 1. Half height vertical PDU (shown horizontally)

Workaround Solution #3: Use an Extra Wide, Regular Depth Cabinet

If there is an extra wide cabinet onsite, it could possibly be used to install an extra depth system.Extra wide cabinets provide sufficient width such that vertical PDUs, mounted at the sides, will not obstruct an extra depth chassis from sliding all the way to the back of the cabinet.Removal of cabinet rear doors may still be required, however, depending on the depth of the system and cabinet.If right angle power connectors are used, then, in some cases, removal of rear doors will not be required (e.g., DGX-1 in the AR3100 cabinet).Using right angle power connectors for connecting to the PDU itself may also allow more horizontal clearance for extra depth systems.In cases where the horizontal clearance is a bit narrow, an extra depth system could be positioned vertically into another rack position, so that it will not have to squeeze between plugs connected into vertical PDUs.Positioning the system vertically to correspond with the height of a meter LCD panel (on a metered PDU), for example, or between power banks (on most PDUs), would allow for more horizontal clearance, since plugs will not be encroaching upon horizontal clearance at these vertical positions.

Table 3. Some Common extra wide cabinets

Some PDU types are deeper than others, meaning the plugs will likely encroach further into the horizontal clearance, since the outlets on the PDU will be at a greater distance from the side of the cabinet.Some Raritan PDUs, for example, have more depth than some APC PDUs.

Workaround Solution #4: Mount Systems at Height Corresponding to Space between PDU Power Banks

As mentioned with workaround #3, it maybe possible to mount an extra depth system at a height so that it will not run into plugs connected to PDUs. This is possible only if the PDUs are sufficiently shallow and if the system is mounted at a height corresponding to the space between PDU power banks, where no plugs protrude.

For example, an IBM Power9 system (33.3″ depth) will still fit into an APC 3100 regular depth cabinet, with four vertical AP7541 PDUs installed at the back of the cabinet, as long as it is installed at a height between the PDU power banks.

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Acoustic Considerations – Fan Noise

Microway’s server systems provide intelligent cooling fans which ramp up and down with system load. However, most systems are very high-density with more than 1,000 Watts consumed per rack unit. Cooling such systems requires high-speed fans which generate significant noise. Most cluster systems will generate 60 dB to 80 dB. This noise level may be subject to safety regulations (e.g., OSHA) and will be audible from other offices in the building. It is recommended that your cluster be placed in a location designed for servers.

If noise is a concern, many of Microway’s workstations – most notably the WhisperStation – are designed to be very quiet and comfortable for an office environment. Quiet HPC Clusters built from Microway WhisperStations are available. If you have any concerns, discuss these matters with your salesperson. In general, if it’s not a WhisperStation you should consider whether the system is appropriate for a lab or office environment.

Power

Microway servers feature auto-switching power supplies which accept both 120V and 208V power, so there are a variety of options when powering multiple computers. The most common electrical circuits are pictured below. Your salesperson can provide a customized recommendation including the rackmount cabinet, power distribution units and optional UPS backup power.

In general, 208V is recommended over 120V. Using 208V allows more systems to run on a single circuit, and each system runs several percent more efficiently.

120V 20A NEMA 5-20 and L5-20 Electrical Outlets

After a 20% de-rating for safety, these circuits supply up to 1,920 Watts of power.

120V 30A NEMA L5-30 Electrical Outlets

After a 20% de-rating for safety, these circuits supply up to 2,880 Watts of power.

208V 20A NEMA L6-20 Electrical Outlets

After a 20% de-rating for safety, these circuits supply up to 3,328 Watts of power.

208V 30A NEMA L6-30 Electrical Outlets

After a 20% de-rating for safety, these circuits supply up to 4,992 Watts of power.

3-Phase 208V NEMA L21-20 Electrical Outlets

After safety de-rating, these circuits supply up to 5,700 Watts of power.

3-Phase 208V CS 8365 Electrical Outlets

After safety de-rating, these circuits supply up to 14,400 Watts of power. Depending upon which PDU is selected, the actual load on each PDU may need to be less – 10kW, 12.6kW or 14.4kW.

Before assuming a particular circuit layout will be sufficient for your new equipment, review:

• Is other equipment already connected to the electrical circuit? It is common for multiple outlets to connect to the same circuit, so don’t assume that an empty outlet means power is available. You will need to perform an inventory of the power required by your existing equipment.
• Particularly for smaller circuits: will you be able to evenly split your servers across multiple circuits? Three 1,000W systems will not successfully connect to two 1,500W circuits. Determine how much electricians will charge for installation of multiple circuits, because it is likely that a single large circuit will be a better choice.

Cooling

Groups of computers typically require special cooling arrangements – your building air-conditioning is designed for offices and will not be able to keep up with the load of compute servers. Note that some facilities reduce or shut down air-conditioning during holidays and weekends. Systems will overheat if they are run in a closed room without sufficient cooling.

A server room or datacenter is the best location for your systems. Microway servers and clusters are designed for installation in industry-standard rackmount cabinets, so you should have no concern when using your own cabinets. We can also provide cabinets with network and power cables pre-wired.

Many facilities specify a maximum power load per rackmount cabinet. You may be restricted to only 7kW or 10kW per cabinet, which would result in racks which are only half-filled. To be certain, present the cooling requirements (provided by your salesperson) to your facilities manager. Your facilities personnel will have details on the cooling load limitations of the datacenter/server room.

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Acoustic Considerations – Fan Noise

Most single computers can be powered and cooled within an office environment. However, some systems contain high-speed fans which generate loud noise. In some cases, an office worker may decide this is acceptable. In others, the noise may be subject to safety regulations (e.g., OSHA) and will be audible from other offices in the building.

Many of Microway’s workstations – most notably the WhisperStation – are designed to be very quiet and comfortable for an office environment. Other systems contain so many high-power components that they simply cannot be quietly cooled.

In contrast with other vendors, Microway does not re-brand servers as workstations. We will provide an honest assessment of system noise. If you have any concerns, discuss these matters with your salesperson. In general, if it’s not a WhisperStation you should consider whether the system is appropriate for an office environment.

Power

Most single Microway computers can be powered from a standard wall outlet. For groups of computers, there are better options than those listed below – see Power and Cooling for Multiple Computers.

Home / Small Office Electrical Outlets

These power outlets provide 15 Amps at 120V and are designated NEMA 5-15. After a 20% de-rating for safety, the NEMA 5-15 can supply up to 1440 Watts of power.

There are several cases when 15A 120V outlets are not sufficient:

• Other equipment is already connected to the electrical circuit. It is common for multiple outlets to connect to the same circuit, so don’t assume that an empty outlet means power is available. You will need to perform an inventory of the power required by your existing equipment.
• You would like to provide a backup power solution (UPS) and the system consumes more than 1000 Watts.
• Servers with more than four GPU accelerators or coprocessors will consume more than 1440 Watts.
• Your system is a Twin or Blade server which actually contains multiple computers. These systems almost always consume more than 1440 Watts.

Commercial Electrical Outlets

These power outlets provide 20 Amps at 120V and are designated NEMA 5-20. After a 20% de-rating for safety, the NEMA 5-20 can supply up to 1920 Watts of power.

This type of outlet is common in office buildings, medical centers and universities, but is not universal. Double-check to be certain your area actually has this type of power circuit. Also verify that it is not designated for special purposes, such as emergency power.

Although this outlet should be sufficient for almost all systems, consider:

• Other equipment may already be connected to the electrical circuit. It is common for multiple outlets to connect to the same circuit, so don’t assume that an empty outlet means power is available. You will need to perform an inventory of the power required by your existing equipment.
• Servers with more than four GPU accelerators or coprocessors may consume more than 1920 Watts.
• If this is a Blade chassis with multiple computers, it will consume more than 1920 Watts.

Cooling

Systems in this category can typically be run without special cooling arrangements – the building air-conditioning will be able to keep up with the load.

Note that some facilities reduce or shut down air-conditioning during holidays and weekends. Many systems will overheat if they are run in a closed room without sufficient cooling. You may need to make special arrangements.

To be certain, present the cooling requirements (provided by your salesperson) to your facilities manager. Your facilities personnel should be able to determine if issues will occur.

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