Solution if the performance of block devices in the AIX system is poor

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Solution if the performance of block devices in the AIX system is poor:
Use the dd command to test the performance of block devices in the AIX system. The test result is 30 MB/s, which is poor.
dd command: dd if=/dev/updisk0 of=/dev/null bs=1024K
Block devices in the AIX system can be used only for the transmission of data with a specified size. In this case, I/Os must pass through the kernel buffer cache. In contrast, raw devices read data from or write data to disks directly bypassing the operating system. In this way, different from block devices, I/O requests will not be split and processed and therefore, performance will not be impacted.
In the AIX operating system, you are advised to use raw devices. A block device is /dev/updisk0 and a raw device is /dev/rupdisk0.

Other related questions:
Common methods to locate the cause of poor performance
Refer to Revelations of Troublesolving cases on the right.

Method used to locate LUNs with poor read and write performance
Method used to locate LUNs with poor read and write performance: 1. The LUN write policy is write through. Locate the cause why the LUN write policy is write through. 2. If the host interface is iSCSI, check whether the network rate is 1 Gbit/s, whether the network is stable, and whether ping packets are lost. If the Fibre Channel or SAS network is used, log in to the storage's OSM page to check whether an alarm indicating that the front end encounters continuous error codes is reported. 3. Check whether slow disks exist in RAID groups. Specifically, run iostat -x 1 to check whether some disks differ from other disks (the util value of one or two disks is greater than that of other disks and reaches 100. If the util value of all disks in the RAID group reaches about 100, the configurations are incorrect and back-end disks are slow disks). If slow disks exist, replace them. 4. If a file system exists on the host, the file system produces enormous fragments when the disk space utilization rate exceeds 90%, causing the deterioration of read/write performance. You are advised to use disk space correctly.

Will the device management be affected if an interface with loop detected is blocked
The blocked interface does not affect device management because the ping and Telnet functions are not affected. Blocking the interface only affect Layer 2 forwarding on the interface because the blocked interface does not learn MAC addresses.

Solution to the problem that the AIX minicomputer fails to connect to the array for the first time
Symptom: When the AIX minicomputer is connected to the array using FC SAN for the first time, the WWN of the host cannot be detected when the Fibre Channel port on the array is displayed as offline or the initiator is added. Solution The AIX minicomputer responds slowly to the device accessing it for the first time. You need to delete the device connected to the Fibre Channel port on the host and scan for the device again to make the configuration take effect. After connecting the Fibre Channel cable, restart the AIX minicomputer.

HUAWEI SAN Storage Host Connectivity Guide for AIX
You can obtain HUAWEI SAN Storage Host Connectivity Guide for AIX from .

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