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AZ-305 · Question #210

Drag and Drop Question You are designing a virtual machine that will run Microsoft SQL Server and will contain two data disks. The first data disk will store log files, and the second data disk will…

The correct answer is Log: None; Data: ReadOnly. For SQL Server log disks, 'None' caching is recommended because log files are written sequentially and rarely re-read, so caching provides no benefit and could even introduce latency or data integrity risks during write operations. For data disks storing SQL Server data files…

Submitted by packet_pusher· Mar 6, 2026Design and implement storage for Azure compute workloads, specifically optimizing disk caching policies for SQL Server virtual machines to meet performance and reliability requirements.

Question

Drag and Drop Question You are designing a virtual machine that will run Microsoft SQL Server and will contain two data disks. The first data disk will store log files, and the second data disk will store data. Both disks are P40 managed disks. You need to recommend a caching policy for each disk. The policy must provide the best overall performance for the virtual machine. Which caching policy should you recommend for each disk? To answer, drag the appropriate policies to the correct disks. Each policy may be used once, more than once, or not at all. You may need to drag the split bar between panes or scroll to view content. NOTE: Each correct selection is worth one point. Answer:

Exhibit

AZ-305 question #210 exhibit

Answer Area

Drag items

NoneReadOnlyReadWrite

Correct arrangement

  • Log: None
  • Data: ReadOnly

Explanation

For SQL Server log disks, 'None' caching is recommended because log files are written sequentially and rarely re-read, so caching provides no benefit and could even introduce latency or data integrity risks during write operations. For data disks storing SQL Server data files, 'ReadOnly' caching is ideal because data pages are frequently read and re-read, so caching reads in the host cache significantly improves performance, while all writes bypass the cache and go directly to durable storage. 'ReadWrite' is avoided for data disks because SQL Server manages its own write caching internally, and enabling host-level ReadWrite caching on data disks can risk data corruption if the VM is interrupted before the cache is flushed to disk.

Topics

#Azure Managed Disks#SQL Server on Azure VMs#Disk Caching Policies#Azure Storage Performance

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