Processor Performance Factors - IBM FlashSystem 710 User Manual

Processor performance factors

At a certain point, processor performance can limit data transfer rates. Determine whether the server's
processor resources are the limiting factor in performance while you benchmark the storage system as a
raw physical device.
Otherwise, an improperly tuned file system or application can make the processor seem to be the limiting
factor when it is not. Complete raw device testing after you set up any multipathing.
There are a few ways to decrease processor usage without increasing processor resources. Certain data
usage patterns can be processor-intensive and fully use the processor. These usually involve small
transfer sizes. When possible, increasing the average transfer size decreases processor usage and offers
better performance.
Another way to decrease processor usage is by enabling interrupt coalescing. Interrupt coalescing is an
HBA-dependent function that decreases processor usage at the expense of latency. This function delays
the calling of the HBA transfer interrupt until several transfers are ready. However, in general, do not
enable interrupt coalescing because the storage system performance benefits from low latency. For more
information, see your HBA documentation.
Connecting the Fibre Channel or InfiniBand ports
Connect the Fibre Channel (FC) ports on the storage system to your server or to an FC switch. If your
storage system has InfiniBand ports, connect them to an InfiniBand switch or host channel adapter (HCA)
in your server.
The following figure shows the port layout for the storage system. Each controller has two FC ports: A
and B, on the left and right respectively. The FC ports on the system can connect to Point-to-Point
(N-Port), Arbitrated Loop (NL-port), or Switched Fabric (F-Port) topologies at 2 Gb, 4 Gb, or 8 Gb speeds.
Figure 1. Fibre Channel or InfiniBand port locations
Although Figure 1 shows FC controller cards, an InfiniBand controller card can occupy either of the same
slots as the FC controller cards. The InfiniBand controller card has two x4 InfiniBand ports: A and B, on
the top and bottom respectively. The InfiniBand ports can connect to Quad Data Rate (QDR), Double
Data Rate (DDR), or Single Data Rate (SDR) HCAs. This connection uses the Small Computer System
Interface (SCSI) remote direct memory access (RDMA) Protocol (SRP).
v On an FC controller card, the FC port LED is green if the speed is set to 8 Gb. If the speed is set to 4
Gb, the LED for the FC port is amber.
v On an InfiniBand controller card, the port LED is green when the link is established.
Connecting the system to a management network
Your system includes a Gigabit Ethernet management controller port (MCP) connection for remote
management over a network.
You use this connection to configure the system's storage and management functions.
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IBM FlashSystem 710 User's Guide