To study for VMware HCI Master Specialist Exam | vSAN认证考试题目学习
76. During a vSAN design workshop, an architect collected the following customer requirements:
- Reduce the impact of disk failure on a vSAN capacity node.
- Reduce the need for a rebuild upon disk failure.
- Achieve the best performance for application workloads.
- Leverage the amount of available vSAN space efficiently.
The customer has already purchased all hardware and therefore the vSAN 7.0U1 cluster is constrained to one Disk Group per node.
Which vSAN cluster option should the architect enable to meet these requirements?
- A. Deduplication and Compression
- B. Compression only
- C. Data-at-rest encryption
- D. Deduplication only
Explaination:
The article from VMware’s “Virtual Blocks Blog” titled “Space Efficiency Using the New ‘Compression only’ Option in vSAN 7 U1” https://blogs.vmware.com/virtualblocks/2020/09/22/space-efficiency-using-the-new-compression-only-option-in-vsan-7-u1/ highlights the benefits of the ‘Compression only’ option in vSAN 7 U1. This option is particularly advantageous for clusters with demanding workloads that typically do not benefit from deduplication techniques. It offers a balance of performance and space efficiency, accommodating the economics of flash storage while focusing on performance for high-demand, latency-sensitive workloads.
Key advantages of the ‘Compression only’ option include:
- Reduced failure domain of a capacity device failure, limiting the impact to the individual storage device rather than the entire disk group.
- Increased destaging rates of data from the buffer tier to the capacity tier, which avoids write amplification inherent in deduplication techniques and improves destage rates.
In terms of performance, using ‘Compression only’ can be superior to both no space efficiency and deduplication and compression (DD&C). It is particularly beneficial for workloads with large working sets issuing large sequential and medium-sized random writes. The absence of the deduplication engine and improved parallelization of destaging allows for faster destaging and reduces the likelihood of hitting buffer fullness thresholds that impact VM latency.
Given these advantages, especially in reducing the impact of disk failure on a vSAN capacity node, reducing the need for a rebuild upon disk failure, and achieving the best performance for application workloads, while efficiently leveraging available vSAN space, the most suitable option for the architect to enable in the vSAN cluster, considering the constraints and requirements provided, would be:
B. Compression only
This option aligns with the customer’s requirements of balancing performance with space efficiency, without the additional overhead and potential performance impacts associated with deduplication.
76. 在vSAN设计研讨会上，一位架构师收集到以下客户需求：
- 减少磁盘故障对vSAN容量节点的影响。
- 减少磁盘故障后重建的需要。
- 为应用程序工作负载实现最佳性能。
- 有效利用可用的vSAN空间。
客户已经购买了所有硬件，因此vSAN 7.0U1集群被限制为每个节点一个磁盘组。
为了满足这些要求，架构师应该启用哪个vSAN集群选项？
- A. 去重和压缩
- B. 仅压缩
- C. 静态数据加密
- D. 仅去重
解释：
VMware的”Virtual Blocks Blog”上的文章《使用vSAN 7 U1中的新’仅压缩’选项实现空间效率》(https://blogs.vmware.com/virtualblocks/2020/09/22/space-efficiency-using-the-new-compression-only-option-in-vsan-7-u1/) 强调了vSAN 7 U1中’仅压缩’选项的好处。这个选项特别适用于典型不从去重技术中受益的需求苛刻的工作负载的集群。它提供了性能和空间效率的平衡，适应闪存存储的经济性，同时专注于高需求、对延迟敏感的工作负载的性能。
‘仅压缩’选项的主要优势包括：
减少容量设备故障的故障域，将影响限制在单个存储设备而不是整个磁盘组。
提高了数据从缓冲层到容量层的去阶段速率，避免了去重技术中固有的写放大，并提高了去阶段速率。
在性能方面，使用’仅压缩’可能比不使用空间效率和去重及压缩(DD&C)更优。它特别适用于有大工作集、发出大量顺序写和中等大小随机写的工作负载。去重引擎的缺失和去阶段的改进并行化允许更快的去阶段，减少了达到影响VM延迟的缓冲区满阈值的可能性。
鉴于这些优势，特别是在减少磁盘故障对vSAN容量节点的影响、减少磁盘故障后重建的需要，以及实现应用程序工作负载的最佳性能方面，同时有效利用可用的vSAN空间，考虑到提供的约束和要求，架构师在vSAN集群中启用的最合适的选项将是：
B. 仅压缩
这个选项符合客户在性能与空间效率之间取得平衡的需求，而没有额外的开销和可能与去重相关的性能影响。
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