Shown in the upcoming figures (Figure 80 on page 94 and Figure 81 on page 96) are
graphical representations of SAS cabling in a DPE-based VNX storage platform, the
VNX5300 File. 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 80 on page 94 shows the first example of a VNX5300 File platform with two DAEs
(one 3U, 15 disk drive DAE and the other a 2U, 25 disk drive DAE) or a VNX5300 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).
The SAS ports on the VNX5300 platform 3U 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 80 on page 94, 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 VNX5300 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 VNX5300 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.
Notice the description of the cable labels affixed to the SP to DAE cables.
The cables shown in Figure 81 are:
Note: The cable colors shown in the example are orange for Bus 0 and blue for Bus 1.
◆ Cable 1, blue, DPE to 1st DAE (labels SP A SAS 1 to LCC A)
◆ Cable 2, blue, DPE to 1st DAE (labels SP B SAS 1 to LCC B)
◆ Cable 3, orange, DPE to 2nd DAE (labels SP A SAS 0 to LCC A)
◆ Cable 4, orange, DPE to 2nd DAE (labels SP B SAS 0 to LCC B)