Host Caching

Question

Hi Team,

I would like to know about Host caching in Azure disk. By default OS disk will be read/write.

Could you please let me know what is the use case of Host Caching and when we can enable?

Which type of workload requires host caching?

Answer 1

Hello Mahavir Saroj

Host caching is a feature of Azure virtual machines that allows you to cache data from Azure disks in the memory of the virtual machine. This can improve the performance of reads from the disk, especially for workloads that access the same data frequently.

By default, OS disks are configured with read/write caching enabled. This means that the operating system and any applications that are installed on the OS disk can read and write data to the cache. Data disks can be configured with read-only or read/write caching. Read-only caching is recommended for workloads that only read data from the disk, such as a database server. Read/write caching can be used for workloads that do a mix of read and write operations, such as a web server.

Host caching is a good choice for workloads that have the following characteristics:

• Frequently access the same data.
• Are sensitive to latency.
• Can tolerate some data loss.

Some examples of workloads that can benefit from host caching include:

• Database servers
• Web servers
• File servers
• Content delivery networks
• High-performance computing applications

Host caching is not a good choice for workloads that have the following characteristics:

• Write frequently to the disk.
• Cannot tolerate any data loss.

Some examples of workloads that should not use host caching include:

• Transactional databases
• Email servers
• File systems that are used for backups
• Mission-critical applications

Here are some things to keep in mind when using host caching:

• The amount of data that can be cached is limited by the amount of memory in the virtual machine.
• Host caching can increase the latency for writes to the disk.
• Host caching can lead to data loss if the virtual machine is unexpectedly shut down.

I hope this helps! Let me know if you have any other questions.