HP VMA-series Memory Arrays Manual do Utilizador descarregar pdf (Página 173)

Network-Layer Performance Testing

HP-AM456-9002A Rev 01

VMA-series Memory Array Installation and Service Guide

173

• Performance Testing Using perf_test on page 174

Preliminary Network-Layer Checks

The Memory Array is designed for high-bandwidth connections via either single

PCIe x8 G1 or dual PCIe x4 G1.

Where the Memory Array is connected to the host, check the following factors

to achieve the best possible performance from your Memory Array:

• PCIe Bridge Slot Sharing on page 173

• PCIe Slots Rated for x4 on page 173

• PCIe Payload on page 173

PCIe Bridge Slot Sharing

Many host systems share PCIe data lanes among two or more physical slots.

Individually, a slot may be x8 electrically, but it may share those eight lanes with

another slot or be restricted by an upstream PCIe switch.

In effect, the aggregate bandwidth when both slots are fully used would not be

greater than x8 speeds. This can hinder each device to 50% of its capable

bandwidth or worse. Be mindful of the PCIe slot routing for your host server to

make the best use for IOPS and bandwidth.

PCIe Slots Rated for x4

Even though a PCIe slot connector may appear to physically support a x8 or even

x16 card, the connected electrical lanes may only be x4. Many host servers have

a mixture of PCIe slots available, such as x4 and x8. Check the data sheet for your

host computer to make sure that the PCIe adapter card is plugged into a x8

electrically capable slot.

PCIe Payload

The maximum payload size configured for the host’s PCIe adapter and the

upstream PCIe bridge devices can limit bandwidth speeds.

Intel x86/x64 CPU-based systems generally can handle a payload size of 256-

bytes. BIOS vendors often leave this configured to the default value of 128-bytes.

Certain AMD64 servers can be configured to handle a payload as high as 512-

bytes, depending on bridge chips used.

Testing has shown that a read bandwidth of 1.7 GB/s is achievable with a 512-

byte PCIe payload, whereas a 128-byte payload might be limited to 1.2 GB/s. In

some cases, upgrading a host server to the latest BIOS version will increase the

default configured payload.

1 2 ... 168 169 170 171 172 173 174 175 176 177 178 ... 299 300

Sem comentários

HP VMA-series Memory Arrays Manual do Utilizador Página 173