48 EMC VNX5300 Hardware Information Guide
VNX5100 Block DAE cabling
VNX5100 Block DAE cabling
The DAE(s) that are to be directly connected to the DPE need to be located close enough to
the DPE so that the DPE-to-DAE interconnect cables (that are provided with every DAE) can
be routed and connected to the DPE.
Shown in the upcoming figures (Figure 40 on page 50 and Figure 41 on page 52) are
graphical representations of SAS cabling in a DPE-based VNX storage platform, the
VNX5100. The Storage Processors connect to the DAEs with SAS cables. The cables
connect LCCs in the DAEs of a storage platform in a daisy chain topology.
The DPE is automatically Enclosure 0 (EA0). The DAE connected to SAS output port 0 is
Enclosure 1 (EA1).
The first DAE connected to the Storage Processor SAS output port 1 is designated
Enclosure 0 (EA0). Each DAE connected after the first DAE increments the enclosure
number by one. All enclosures connected to SAS Port 0 will show an ID of 0, but the
addresses will increment.
Figure 40 on page 50 shows the first example of a VNX5100 platform with two DAEs (one
3U, 15 disk drive DAE and the other a 2U, 25 disk drive DAE) or a VNX5100 platform with a
total of from 55 disk drives (if the DPE is a 3U, 15 disk drive device) or 65 disk drives (if the
DPE is a 3U, 25 disk drive device).
Do Not
connect more DAEs than the VNX5500 platform can support. When calculating the
number of drives for your VNX5500 platform, the DPE is included in the total drive slot
quantity of 55 to 65 drives. If the total drive slot quantity exceeds 55 or 65, you will not be
able to add another DAE.
The SAS ports on the VNX5100 platform DPE are labeled 0 and 1. SAS 0 is connected
internally to the SAS expander that connects the internal DPE disks. Since SAS 0 is already
connected internally to the DPE disks, the first DAE is connected to SAS 1 to balance the
load on the SAS ports. The second DAE is connected to SAS 0, the third DAE is connected
to SAS 1, and so on.
In Figure 40 on page 50, notice that each DAE device supports two completely redundant
buses (LCC A and LCC B).
The rule of load or bus balancing is applied to all DAEs. That is, Bus 0 is Enclosure Address
0 (EA0), Bus 1 is EA0, and so on. In the case of the VNX5100 platform, Bus 0 EA0 is the
DPE (SP A and B). So, to balance the load, Bus 1 EA0 becomes the first DAE (LCC A and B)
in the cabinet with the next DAE (LCC A and LCC B) as Bus 0 EA1, and so on. If you have
several DAEs in your VNX5100 platform, you can daisy chain them within that bus.
However, it is recommended that you balance each bus. In other words, always optimize
your environment by using every available bus, and spreading the number of enclosures
as evenly as possible across the buses.
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