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The following sections provide information on expected maximum performance from different hardware components of Dell Unity. Dell Technologies does not recommend continuously operating a hardware resource near its maximum potential. When utilization is below the maximum level, average response times will be better, the system will be able to handle activity bursts without becoming overloaded, and performance may still be maintained during hardware failure scenarios.
For some of the following hardware sections, both IOPS and bandwidth (MB/s) capabilities are shown. A different type of workload is assumed when determining IOPS capabilities versus when determining bandwidth capabilities:
This data is offered as a guideline for what most customers can expect for maximum performance capabilities from certain hardware. Note that individual components in your specific system may be able to provide higher or lower numbers, based on differences in workload characteristics and environment.
Most hardware components in the Dell Unity system can be monitored in Unisphere, via the System Performance page.
Dell Unity is designed to achieve the maximum performance possible from today’s multi-core processors. The Dell Unity architecture results in non-linear CPU utilization increases as the workload scales.
EXAMPLE: A Dell Unity system reporting 50% CPU might still be capable of providing more than 3 times the current workload.
It is recommended to balance workload across the 2 SPs, such that CPU utilization is roughly equivalent on each SP.
Table 2 provides recommended operating ranges, in terms of sustained CPU utilization. Brief spikes of high utilization are normal and expected on any system. The following values refer to average sustained levels over long periods of time. This table also provides the expected system behavior in the case that a single SP would need to service the entire workload (such as coordinated reboots during upgrades, or if a single SP fails, etc.).
Reported CPU utilization | Analysis | Expected single-SP behavior | Enable data reduction? | Enable snapshots and/or replication |
Below 50% (Low utilization) | System is capable of accepting additional features and workloads. | A single SP should be able to service the entire workload while maintaining existing IOPS and response time. | Data Reduction can be enabled on the storage objects in this system. | Snapshots and Replication can be enabled on the storage objects in this system. |
50%-70% (Normal utilization) | System is operating normally, and may be capable of accepting additional features and workloads. | A single SP should be able to service the entire workload while maintaining existing IOPS and response time. | Choose the best candidate storage objects, and enable Data Reduction on only a few at a time (see the Data Reduction section) | Enable Snapshots or Replication on only a few storage objects at a time. |
70%-90% (High utilization) | System is nearing saturation; carefully consider whether additional features and workload should be added to this system. | A single SP should be able to maintain the existing IOPS load; however, increases in response time may be experienced. | Data Reduction should not be enabled on any additional storage objects in this system. | Choose the best candidate storage objects, and enable Snapshots or Replication on only a few at a time (see the Snapshots section). |
Above 90% (Extremely high utilization) | System is saturated; additional workload should not be applied to the system; consider moving some work to other systems. | A single SP will likely not be able to maintain the existing IOPS load. | Do not enable Data Reduction on any additional storage objects in this system. | Do not enable Snapshots or Replication on any additional storage objects in this system. |
The following tables provide maximum expected IOPS and bandwidth from the different ports which are available in the Dell Unity system. (Note that the capability of a port does not guarantee that the system can reach that level, nor does it guarantee that performance will scale with additional ports. System capabilities are highly dependent on other configuration parameters.)
SAS ports are used by the SPs to move data to and from the back-end drives; all other ports can be used to provide access to hosts.
Table 3 provides maximum expected IOPS and bandwidth from a 12Gb SAS port. The base Dell Unity configuration contains 4 ports.
Port | Maximum IOPS per port | Maximum MB/s per port |
12Gb SAS On-board or 4-port I/O Module | 250,000 | 2,500 |
Note: that the DPE drives in most Unity systems are serviced by the pair of SAS ports that control SAS Bus 0. In the Dell Unity XT 480/F, 680/F, and 880/F, the DPE drives are directly accessed by the underlying SAS controllers via internal connections. Therefore, DPE-only systems of these models can see higher bandwidth than other DPE-only systems.
Table 4 provides maximum expected IOPS and bandwidth from the front-end ports which provide Block protocols (FC and iSCSI).
Port | Maximum IOPS per port | Maximum MB/s per port |
32Gb FC 4-port I/O Module | 45,000 | 3,000 |
16Gb FC CNA or 4-port I/O Module | 45,000 | 1,500 |
8Gb FC CNA or 4-port I/O Module | 45,000 | 750 |
25GbE iSCSI 4-port mezzanine or I/O Module | 30,000 | 1,700 |
10GbE iSCSI 4-port I/O Module | 30,000 | 1,100 |
10GbE iSCSI CNA or 2-port I/O Module | 25,000 | 900 |
10GBase-T iSCSI On-board, mezzanine, or 4-port I/O Module | 30,000 | 1,100 |
1GBase-T iSCSI On-board, CNA, or 4-port I/O Module | 3,000 | 110 |
Table 5 provides maximum expected IOPS and bandwidth from the front-end ports which provide File protocols (NFS and SMB).
Port | Maximum IOPS per port | Maximum MB/s per port |
25GbE NAS 4-port mezzanine of I/O Module | 60,000 | 2,900 |
10GbE NAS 4-port I/O Module | 60,000 | 1,100 |
10GbE NAS CNA or 2-port I/O Module | 60,000 | 1,100 |
10GBase-T NAS On-board, mezzanine, or 4-port I/O Module | 60,000 | 1,100 |
1GBase-T NAS On-board, CNA, or 4-port I/O Module | 6,000 | 110 |
Individual drives provide varying levels of performance based on the workload which is applied. Workload attributes such as I/O size, access patterns, queue depth, etc., can result in a drive providing more or less IOPS at acceptable response times.
Table 6 provides maximum recommended IOPS per drive for the drive types supported in Dell Unity. In general, Dell Technologies recommends the following values for determining when a drive may be approaching its maximum performance, and therefore may become a bottleneck to system performance. If the drives in a storage pool are observed to sustain an IOPS load near these values for long periods of time, consider adding additional drives to the pool in order to spread the load across more resources.
Drive type | Maximum recommended IOPS per drive |
SAS Flash (all types) | 20,000 |
SAS 15K | 350 |
SAS 10K | 250 |
NL-SAS | 150 |