Troubleshoot SDDDSM error messages

Question: What is SDDDSM ? Often I see Event Log entries referencing SDDDSM , but can’t relate it back to SQL Server. How can I troubleshoot?

Answer: SDDDSM is the Subsystem Device Driver Device Specific Module. The purpose is to support IBM storage devices . It’s a multipath IO system based on the Microsoft MPIO concepts. SDDDSM and MPIO work in conjunction supporting the multipath configurations.

The general advice from IBM is to is to maintain a balanced use of all the paths and keep them active

Use the datapath query adaptstats  to view the number of reads and writes on each adapter. The aim is to maintain a balance of read and writes across the adapters. If you have problems speak to your SAN Storage expert

Typical advice for reducing pressure on IO path pressure includes:

a)      Increase RAM – to increase the cache size and potentially decrease the amount of disk requests

b)      Distribute processing across a number of systems

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