CompTIA A+ Core 1 (220-1201)Virtualization and Cloud ComputingMedium
A systems administrator is configuring a new virtual machine (VM) for a critical database server. The administrator needs to ensure that the VM can achieve maximum disk I/O performance and minimize latency. Which type of virtual disk allocation should be chosen for this purpose?
- ADynamically expanding disk
- BFixed-size disk
- CSparse disk
- DThin provisioned disk
Show answer & explanationAnswer & explanation
Correct answer: B. Fixed-size disk
A fixed-size disk allocates all its storage space at the time of creation, which pre-zeros or pre-allocates the necessary blocks. This eliminates the overhead of dynamically expanding the disk and reduces potential fragmentation, leading to better I/O performance and lower latency for critical applications like database servers.
Why the other options are wrong
- A. Dynamically expanding disks are another term for thin provisioned disks and suffer from the same performance limitations.
- C. Sparse disks are similar to thin provisioned disks, growing as data is written, which isn't ideal for performance-critical applications.
- D. Thin provisioned disks allocate space as needed, which can introduce I/O overhead as the disk grows.
Fixed-size Virtual Disk
A virtual disk type where all the storage space is allocated and reserved on the physical host at the time of its creation, regardless of how much data is initially stored within the VM.
- Allocates full size immediately.
- Offers best performance for disk I/O.
- Consumes more physical storage upfront.
Memory trick: For 'FIXED' performance, fix the size.