Exam DP-300 topic 3 question 36 discussion

I think it should be opposite, i.e. Read-Only and None. See https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/performance-guidelines-best-practices-storage?view=azuresql#caching We need to set 'Read-Only' caching for data disks and 'None' for the log disk. There is a loop (copy) in the ARM template, it evaluates whether current disk ID is greater than sum of data disks. If yes then it's the log disk, so assign None, otherwise the value in the variable (i.e. Read-Only). Similar example is here: https://learn.microsoft.com/en-us/azure/azure-sql/virtual-machines/windows/create-sql-vm-resource-manager-template

Select ReadOnly caching. This is because SQL Server frequently reads from the data disks but doesn't perform as many writes, so ReadOnly caching maximizes read performance while keeping write operations off the cache. For log disks: Select None for caching. SQL Server log writes are sequential and write-heavy. Disk caching can interfere with the efficient, sequential logging, so you should disable caching to ensure the best performance for log writes.

Answers are the other way around as licna suggested. Look at the IF statement for the caching property in the “COPY” section… it reads “If the current disk being created is of a higher index than the number of data disks count, use “log cache value”, otherwise default to caching variable (for data files).

None ReadOnly