Sun Fire [TM] T2000 server: How to Increase I/O and application performance by 100%

Asset ID:	1-71-1005490.1
Update Date:	2017-02-01
Keywords:

Solution Type Technical Instruction Sure

Solution 1005490.1 : Sun Fire [TM] T2000 server: How to Increase I/O and application performance by 100%

Applies to:

Sun Fire T2000 Server - Version All Versions and later
All Platforms

Goal

Description
This document describes the recently found qlc.conf parameter to increase the I/O and application performance on a Sun Fire [TM] T2000 Server by 100%.

Non I/O intensive applications may not see the same benefit.

Solution

Steps to Follow
While benchmarking an application on Sun Fire T2000 server and StorageTek[TM] 6140 array, we found doubled I/O throughput (MB/s) and therefore application performance by 100%.
A relatively unknown, "qlc.conf" parameter, specifically the "pci-max-read-request" has a very low default setting, this restricts I/O performance and therefore makes the T2000 server slow and also does not exploit the full capabilities of Sun storage.

This can be fixed by setting the parameter to a higher value. This is only applicable to Sun Fire T2000 server using PCIe.

Details:

Recommendation:

Set pci-max-read-request=2048 on all Sun Fire T2000 servers.

Parameter explanation:

Set in " /sysconfig/drv/qlc.conf "

#Name: PCI max read request override;

#Type: Integer, bytes; Range: 128, 256, 512, 1024, 2048, 4096

#Usage: This field specifies the value to be used for the PCI max read request, overriding the value programmed by the system.

#NOTE: The minimum value is 128 bytes; if this variable does not exist

or is not equal to 128, 256, 512, 1024, 2048 or 4096, the ISP2xxx

# defaults to values specified by the system.

pci-max-read-request=2048;

Background:

When you write data to a target, you are reading from PCI. The issue is that Sun Fire T2000 server defaults this to 128 bytes.

To get best performance this has to be set to 4096. But it is not that simple. PCI engineers warn that setting this too high will result in eating up resources from other devices on the bus such as Ethernet.

There is currently a project going on in PCI team to make this process automatic. In the meantime people who have set this to 2048 without seeing any issues.

Product
Sun Fire T2000 RoHS Version

Bug ID 6520427 is filed for long-term relief

T2000, performance, I/O, increase, application performance
Previously Published As
88385

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