host-caching

name	host-caching
description	Set ReadOnly, ReadWrite, or None host caching per disk role

Host Caching

When to use this skill

• Configuring OS, data, and log disks
• DB performance tuning

Key concepts

• ReadOnly — best for OS disk and read-heavy data; cache survives VM stop/start.
• ReadWrite — default for OS disk; not safe for transaction logs.
• None — use for write-heavy or strict durability (DB log volumes, journals).
• Cache backed by local SSD on the host — counts against cached IOPS limit on the SKU.

Azure CLI examples

az vm disk attach -g rg --vm-name db1 --name datadisk1 --caching ReadOnly
az vm disk attach -g rg --vm-name db1 --name logdisk1 --caching None

Common pitfalls

• ReadWrite cache on a SQL/Oracle log disk → corruption on host failure.
• Caching limits — cached IOPS share the SKU's cached pool; saturating it throttles all cached disks.

References

• Microsoft Learn: search for "Host Caching Azure VM" on https://learn.microsoft.com

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