R&M Data Center Handbook
R&M Data Center Handbook
R&M Data Center Handbook
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www.datacenter.rdm.com<br />
3.4.2. End of Row (EoR) / Dual End of Row<br />
In an End of Row architecture, a group of server cabinets is supplied by one or more switches. <strong>Data</strong> cables are<br />
installed in a star pattern from the switches to the individual server cabinets. This is generally 3 cables (LAN, SAN,<br />
KVM) for each server, or 5 for redundant LAN & SAN connections. For 32 1U servers, this would then require at<br />
least 96 data cables per cabinet.<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
........<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
PATCH<br />
Aggregation<br />
& Core<br />
SAN<br />
Application Server or Storage Library<br />
SAN Connection<br />
LAN Connection<br />
KVM Connection<br />
Uplink<br />
SAN Switch<br />
LAN Switch<br />
KVM Switch<br />
Since 2010, the performance of virtualized servers has increased dramatically through the systematic introduction<br />
of SR-IOV (Single Root I/O Virtualization) by leading processor manufacturers. Up to that point, data throughput in<br />
virtualized systems was limited to 3 – 4 Gbit/s, and even less than 1 Gbit/s during continuous operation. A doubled<br />
1 GbE connection was therefore the right solution.<br />
The modern alternative is to directly connect servers to high-performance aggregation switches. This solution is<br />
possible because I/O performance in a virtualized system is currently about 20 – 30 Gbit/s, since the hypervisor<br />
(the virtualization software which creates an environment for virtual machines) is freed up from tasks of switching<br />
wherever possible, through SR-IOV and a suitable piece of hardware. There are server blades where, in order to<br />
reach their full potential, a single blade must be connected doubly to 10 GbE. Blade systems that have a total of<br />
up to 8 blade servers must therefore be connected to 100 GbE.<br />
Blade system manufacturers report they are currently working on improving inner aggregation, so a 100 GbE<br />
connection is expected to be offered by 2011. A conventional ToR structure design would therefore be completely<br />
overloaded.<br />
In addition, no cost-effective switches are available on the market which provide the necessary flexibility and can<br />
be equipped with new, high-quality control functions such as DCB, which only make sense when they work endto-end.<br />
An EoR structure therefore has the following features.<br />
Advantages:<br />
Disadvantages:<br />
• Flexible, scalable solution (future-proof) • Greater cable volume in horizontal cabling<br />
• Optimal LAN port assignment (efficient) • Many cable patchings for EoR switches (server and<br />
• Concentration of Access Switches<br />
uplink ports)<br />
(simplified moves/adds/changes)<br />
• Space optimization in racks for server<br />
expansion<br />
Page 60 of 156 © 08/2011 Reichle & De-Massari AG R&M <strong>Data</strong> <strong>Center</strong> <strong>Handbook</strong> V2.0
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