Home > Storage > Unity XT > Storage Admin > Dell Unity XT: Introduction to the Platform > Disk Processor Enclosure (DPE) – 380/F
Dell Unity’s Disk Processor Enclosure (DPE) for Unity XT Series models utilize a 25-drive 2U DPE using 2.5” drives. Note, though, that the Unity XT 380/F uses a different physical chassis than the 480/F, 680/F, and 880/F models. The following figures and related information are specific to the 380/F model. For information about the DPE for the 480/F, 680/F, and 880/F models, see section 3.3 titled Disk Processor Enclosure (DPE) – 480/F, 680/F, 880/F.
For 380/F systems, on the front of the DPEs (see Figure 2) are LEDs for both the enclosure and drives to indicate status and faults. The first four drives of the DPE are known as system drives and contain copies of data used by the operating environment. While they can be used in Pools to hold user data, the entire formatted capacity of the system drives will not be available as some space is reserved for the system. These drives should not be moved within the DPE or relocated to another enclosure and should be replaced immediately in the event of a fault. A system drive cannot be used as a traditional pool hot spare for a non-system drive. For this reason, the minimum number of drives in a system is five with system drives configured in a RAID 1/0 (1+1 or 2+2) configuration including a non-system drive traditional pool hot spare.
The rear of the DPE reveals the Storage Processors (SP) and their on-board connectivity. Each Storage Processor has 2x 12Gb SAS ports, used for connecting additional storage and each SAS port has a 4-lane configuration. For front-end connectivity, the SPs have 2x 10GbE BaseT ports which can auto-negotiate between 10Gb/1Gb/100Mb, and 2x Converged Network Adapter (CNA) ports. These CNA ports can be configured to serve 16Gb/8Gb/4Gb Fibre Channel using either multi-mode or single mode FC SFPs, 10GbE Optical using SFP+ connectors or TwinAx cables in active or passive mode, or 1GbE BaseT using RJ45 SFPs. For optical connections, the CNAs feature full iSCSI offload which relieves the Storage Processor from handling TCP/IP network stack operations. For management and service, each SP has a dedicated 1GbE BaseT management port and a dedicated 1GbE BaseT service port; both ports operate at 1Gb/100Mb/10Mb speeds. In Dell Unity OE version 5.1, management port settings can be customized to match the environment by manually changing MTU, port speed and/or duplex settings. The range of these settings include MTU of 1280-9000, port speeds of 1Gbps, 100Mbps, or 10Mbps, and advertised duplex of full, half, or auto. These settings can be changed using svc_network service command.
The DPE on 380/F systems is internally connected to Bus 0 which is the same bus that the first SAS expansion port is connected to. Therefore, the DPE is recognized by the system as “Bus 0 Enclosure 0” while the first DAE connected to the first SAS expansion port would be “Bus 0 Enclosure 1”. Furthermore, this means that the twenty-five drives in front of the DPE are internally recognized as “Bus 0 Enclosure 0 Drive 0” – “Bus 0 Enclosure 0 Drive 24”.
For a detailed description of the hardware on Unity XT 380/F systems, see the Unity XT Hardware Information Guide on Dell Online Support.
Unity XT 380 and Unity XT 380F Storage Processors manufactured in the second half of 2022 and later have been redesigned and no longer include 10GbE BaseT embedded ports. For the 380 models, this removes 2x 10GbE BaseT ports per SP or 4x total per system. 10GbE BaseT front-end connectivity is still supported by using the 4-port 10GbE I/O module described in the section I/O Module Options – 380/F, 480/F, 680/F, 880/F of this document. Unisphere can be used to confirm if the 10GbE BaseT embedded ports are present on a system. In Unisphere, navigate to SYSTEM > System View > Enclosures > Rear and review the ports on the DPE.
The Unity XT 380/F system is powered by an Intel® Xeon® Processor utilizing Intel’s Broadwell architecture, with six cores per Storage Processor. Each purpose-built system contains two Storage Processors (SPs), which are used for high availability and load balancing purposes.
An M.2 SSD device is located inside each Storage Processor and serves as a backup device in the event of an SP failure (Figure 4). In the event of an SP failure, the memory contents of the SP’s cache are written to the M.2 SSD device so it can be recovered once the SP is restored. If the M.2 SSD device itself encounters a failure, cache data can be recovered from the peer Storage Processor. The M.2 SSD device also holds the boot image that is used to run the operating environment.
Cooling modules or fan packs (Figure 5) are used to provide cool airflow to the Storage Processor’s interior. There are five counter-rotating cooling modules in a Storage Processor for 380/F systems. A Storage Processor can tolerate a single cooling module fault; in which case the surviving fans will increase their speed to compensate for the faulted module. If a second cooling module faults, the Storage Processor will gracefully save cache content and shut down to prevent overheating.
The Battery Backup Unit (BBU) provides power to the Storage Processor if cabinet power is lost. The BBU (Figure 6) is designed to power the SP long enough for the system to store SP write cache content to the M.2 SSD device before powering down. The BBU includes sensors which communicate its charge and health status to the SP. In the event the BBU is discharged, the SP will disable write cache until the BBU has recharged. In the event the BBU has faulted or cannot sustain enough charge, an alert will be generated.
The baffle (Figure 7) directs airflow within the Storage Processor. Cool air drawn in from the cooling modules is directed to the processor and DIMMs for effective thermal management.
There are four Dual-Inline Memory Module (DIMM) slots on a Storage Processor for a 380/F system. These are filled with up with four 16GB DIMMs. An example DIMM is represented in Figure 8. DIMMs use error-correcting code (ECC) to protect against data corruption. If a DIMM is faulted, the system will boot into Service Mode so the faulted DIMM can be replaced.
There are two power supply modules in a Disk Processor Enclosure (DPE), one per Storage Processor. A single power supply is capable of powering the entire DPE. Power supplies can be replaced without having to remove the Storage Processor or shutdown the system. Power supplies are offered for AC power and in Dell Unity OE version 5.2, a NEBS compliant DC variant power supply was introduced for Dell Unity XT 380/F and 480/F models. DC power supplies are not available for the 680/F and 880/F. For Unity XT 380 and 480 DC powered systems, 600GB and 1.8TB 10k SAS NEBS certified as well as 800GB 3WPD SSD NEBS certified drives are available. For Unity XT 380F and 480F DC powered systems, 1.92TB and 3.84TB 1WPD SSD NEBS drives are available.
For more information about Dell Unity DC-powered systems, see the technical paper called Dell Unity DC-Powered Enclosures Installation & Operation Guide.