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The performance decreased after upgrade V3 Storage array to V300R002C10SPC100

Publication Date:  2016-08-29 Views:  30 Downloads:  0
Issue Description

The performance of the SAN decreased after upgrade the OceanStor 5500 V3 to V300R002C10SPC100, use the iometer test the SAN and monitor the performance on DeviceManager.

The latency fo the IO is more than seconds.

Handling Process

1. Search the key words ‘LUN IO timeout’ in the logs to check if there is below output:

 [LUN IO timeout for ctrl,LUN ID(4),opcode(320962560),phrase(12),rec pt(1), latency(1492), thres(1250).]

2. Enter the developer debug mode, run command: rtt show -t all to check the latency of the write cache and write disk from cache.

Latency of write cache:


Latency of write disk:


3. Run command 'quota show pttinfo 0' to check if the cache SSD quota was used up.


4. Run command ‘quota show poolhang 0’ to check if the pool 0 cache is less than 20%.


Root Cause

The cache quota reserved for SSD disks is too small, it is only 512M.

Solution

Follow below steps to adjust the cache water level:

1. Login the CLI and then run command ‘change user_mode current_mode user_mode=developer’ to enter the Developer mode.

2. Run command ‘change disk_domain_possessed general disk_domain_id=0 tier_type=ssd possess_type=page possess_number=131072

Note: 

1. The red part needs to be replaced by actual disk domain id.

2. possess_number is the number of cache pages. The system will adjust the water level automatically according to this parameter.


END