In my last article about Rack Fundamentals, we discussed about how the racks to be chosen for deployment. Once are racks are deployed, and equipment are stacked over it, we need to interconnect them via Cables. Cabling is the key activity when it comes to building of a Datacenter. It does take huge amount of efforts and need specialists to do this activity. It may sound cabling is just plug-in of cable from source to target ports, but is that it?
Designing your DataCenter and implementing its core components is most crucial part to handle when it comes to Managing your DataCenter. This includes all the data cables i.e. your LAN Network Cables (Copper, Fiber) or SAN cables (Copper, Fiber) and Power Distribution Cables.
I don’t think we need to go back to the history about when the cabling of DataCenter was taken into considerations. However, they do play a vital role to understand your Network Topology. Still, I would be giving you an overview just to refresh about the kind of cables we usually use in DataCenter.
Overview of Cable & Connectors:
· Network: CAT5 of Category 5 is used for 100MB connection, while Cat 5e support 1G and Cat6a supports 10G connection. For Network LAN Copper Cables RJ45 is the common connector type, which is supported for Data Speed max up to 1GBPS. You might have seen this with your Broadband connection or office Ethernet connection. For 10G LAN Network, Fiber channel cables are mostly used for connectivity. However, there are 10G Copper cables available, mostly seen used with blade enclosure modular switches. SFP+ are factory installed with 10G copper cables. Even for storage array connectivity within system i.e. from controller to JBOD, mostly 10G Copper SAS cables are used.
· Storage: FC cables are used mostly with Storage SAN connections. The most commonly used are 2G/4G/8G/16G connections. For 1G/2G Yellow color, 2G/4G Orange color, 8G/10G Aqua colors while for 16G Dark Blue color cables are used. FC cables are further connected to respective speed SFP+, note that these SFP+ are backward speed compatible. However If a high speed cable is connected to lower speed SFP+ it will work in respective speed. I have also seen people using certain SFP+ which are used to connect RJ45 cable with 10G ports.
· Power: For Power Distributions, usually 6A/12A cables are used with server, storage & Switches. 12A cable is mostly used with Blade enclosures, High End Servers or with an Enterprise Storage device. Just to recognize, 6A cables are with oval curve and usually seen along with Desktop computers as well, while 12A are rectangular in shape and is uniquely identified.
· Misc Cables: These are equipment specific or management cables like Serial cables, KVM or ILO cables etc
Now I am not getting into the specifications of each cables or the cables to be considered like LC/SC, OM1/2/3/4 etc, that would be a separate chapter all together, which I would cover when I will start discussing about Storage in future blogs. However if you are curious Wiki can help you. I am also not covering how to make these cables or how to connect these cables. For this, I would be making a video shortly in my Video learning series.
For Power Distribution:
· Power from Large UPS or Transformers is taken and stepped down to receive correct voltage and distributed along panel mounted in the columns
· Power is then further distributed from columns to rack mounted power distribution units via Whip (to avoid raised floor expenses).
· Each equipment will be then further wired to these PDU for connection based on their requirements.
· Remember Amp X Voltage = Power; so as the Amp increases or decreased, the gauge of the wire needs to be increase or decrease to accommodate the change.
· Considering the High Availability, always plug-in both the PDU of equipment to different phases or power feeds
Note: Load per rack or circuit load need to considered while wiring these hardware
Cabling Layout Architecture:
· Remember the old school network topology you studied while learning about Networks and we learned how network can be designed with Star, Bus, Ring and Tree topology. Well, for data centers, a Star topology is used.
· Many factors need to be considered while deciding a layout for power distributions e.g. size of the datacenter, kind of equipment, budgets etc
· Usually power distribution panels are installed at the end of the row from where is further distributed across racks in that row. This approach is easy to manage and less expensive as well. Also, it breaks whole circuit into multiple points which avoids a bigger failure in case of any incident.
Data Cabling Practices:
· Follow National Electric Code as Standard for deployment
· Test cable before deployment.
· Prefer Over-head Deployments with cabling trays; not suggest if constant change is expected since not scalable. Note they should have sufficient distance away from sprinklers.
· Don’t tie the cables with Rack
· Don’t over tight the length of the cable, use the right length required. Don’t keep them lose either. Use cable guidance closets for the deployment. Cable guiding trays and their management devices reduces downtime by avoiding human error and over-heating.
· Cables connected via Patch Panels installed over (every) rack. These patch panels are designed and deployed in initial phase of DataCenter deployment.
· Cable back-bone in a rack should be preferred non-scalable. However, it is a best practice to wire as much as possible with latest cable standard during initial deployment.
· Cables should be located behind the walls and should not be in open
· Most important, once the cables are deployed, Label them. I would be writing a my next article regarding best practices for cabling.
Caution: Do consider the scenarios while designing when your patch cable will fail.
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