EMC VNX Series Hardware Information Manual page 111

Cabling with two DAEs in a VNX5500 File/Unified platform
Shown in the upcoming figures
Figure 100 on page 116) are examples of SAS cabling in a DPE-based VNX storage
platform, the VNX5500 File/Unified platform. 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.
Figure 98 on page 112 shows the first example of a VNX5500 File/Unified platform with
two DAEs (one 3U, 15 disk drive DAE and the other a 2U, 25 disk drive DAE) or a VNX5500
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).
IMPORTANT
When balancing the load the between buses, take the following into consideration: the
DPE is 0,0, the 1st DAE is 1,0 (port 1), the 2nd DAE is 0,1, and so on.
The SAS ports on the VNX5500 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 98 on page 112, 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 VNX5500 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 VNX5500 platform, you can daisy chain them within that
particular 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.
Note: On the DPE and DAE, each cable connector includes a symbol to denote the
direction the cable needs to connect to. The cable connector that has a double circle
symbol is the input to the device. The cable connector with the double diamond
symbol is the output from the device.
IMPORTANT
Notice the description of the cable labels affixed to the SP to DAE cables.
(Figure 98 on page 112, Figure 99 on page
VNX5500 Hardware Information Guide
VNX5500 DAE cabling
114, and
111