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Low Performance of Oracle Databases in a HyperMetro Project

Publication Date:  2019-04-10 Views:  235 Downloads:  0

Issue Description

In a customer environment, OceanStor 18500 V3 is used and equipped with HyperMetro, the two data centers are 30 km in distance and use wave-division multiplexing (WDM) devices for interconnection, and three nodes deployed as an Oracle RAC (2+1) cluster. The customer database engineers think frequent locking and unlocking operations required by the current HyperMetro structure affects the performance of Oracle RAC so seriously that the RAC even cannot support the rollout of their core service systems.

Alarm Information

Low performance

Handling Process

1. Collect host logs.

2. Collect multipathing logs.

3. Collect storage logs.

4. Collect switch logs.

Log analysis indicates that no alarm information exists, data I/Os are moral, storage logs and status monitoring are normal, and local reads and writes are normal.

Perform performance tests in three scenarios:

1. Use hosts and databases to initiate read and write requests to and perform pressure tests on the local storage. The local storage meets the storage performance requirements and is proved to be normal.

2. Use the hosts in the customer building to initiate read and write requests to and perform pressure tests on the storage in the customer building. The storage the storage performance requirements and is proved to be normal.

3. Use hosts and databases in the science park to perform pressure tests on the storage in the customer building. The performance is low.

Check the WDM devices. The devices are normal. Check the FC switches and analyze logs. Log in to FC switches and run the licenseshow command to check the license information. FC switches do not have the license for remote transmission.

Root Cause

FC switches do not have the license for remote transmission.

Solution

1. Inform the customer to buy the license for remote transmission.

2. Configure remote connection.

IBM_2498_B24:admin> portcfglongdistance 1 LS 1 40  (The LS remote connection is enabled for port 1, and the specified distance is 40 km.)

Check the switch status after remote connection is configured:

IBM_2498_B24:admin> switchshow

switchName: IBM_2498_B24

switchWwn: 10:00:00:05:33:42:xx:xx

Index Port Address Media Speed State Proto

==============================================

0 0 0a0000 id N4 Online FC F-Port 20:16:00:a0:b8:6e:xx:xx

1 1 0a0100 id 2G Online FC LD E-Port 10:00:00:05:33:41:xx:xx "IBM_2498_B24 "

(upstream)

2 2 0a0200 id 2G No_Light FC

3 3 0a0300 id N4 No_Light FC

4 4 0a0400 id N4 No_Light FC

5 5 0a0500 id N4 No_Light FC

6 6 0a0600 id N4 Online FC F-Port 20:46:00:a0:b8:6e:xx:xx

7 7 0a0700 id N4 Online FC F-Port 20:47:00:a0:b8:6e:xx:xx

8 8 0a0800 id N8 No_Light FC (No POD License) Disabled

……..

Check the port status. Port 1 is in E_port cascading mode, the detected connection distance is 21 km, 27 buffers are needed, and the largest buffer value is 31.

IBM_2498_B24:admin> portbuffershow 1

User Port Lx Max/Resv Buffer Needed Link Remaining

Port Type Mode Buffers Usage Buffers Distance Buffers

---- ---- ---- ------- ------ ------- --------- ----------

0 F - 8 8 - -

1 E LD 31 27 27 21km

2 - 8 0 - -

3 -

After the preceding configurations, the cascading configuration for remote connection is complete.

Suggestions

If the distance between two HyperMetro data centers is longer than 10 km, configure the license for remote connection on FC switches. If the distance is longer than 25 km, configure WDM devices.

END