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Category Archives: Storage

ESX IP Storage Troubleshooting Best Practice White Paper

We have published an ESX IP Storage Troubleshooting Best Practice white paper in which we recommend vSphere customers deploying ESX IP storage over 10G networks to include 10G packet capture systems as a best practice to ensure network visibility.

The white paper explores the challenges and alternatives for packet capture in a vSphere environment with IP storage (NFS, iSCSI) datastores over a 10G network, and explains why traditional techniques for capturing packet traces on 1G networks will suffer from severe limitations (capture drops and inaccurate timestamps) when used for 10G networks. Although commercial 10G packet capture systems are commonly available, they may be beyond the budget of some vSphere customers. We present the design of a self-assembled 10G packet capture solution that can be built using commercial components relatively inexpensively. The self-assembled solution is optimized for common troubleshooting scenarios where short duration packet captures can satisfy most analysis requirements.

Our experience troubleshooting a large number of IP storage issues has shown that the ability to capture and analyze packet traces in an ESX IP storage environment can significantly reduce the mean time to resolution for serious functional and performance issues. When reporting an IP storage problem to VMware or to a storage array vendor, an accompanying packet trace file is a great piece of evidence that can significantly reduce the time required by the responsible engineering teams to identify the problem.

SPBM Performance Whitepaper

New Fling released – IOInsight

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By Sankaran Sivathanu

VMware IOInsight is a tool to help people understand a VM’s storage I/O behavior. By understanding their VM’s I/O characteristics, customers can make better decisions about storage capacity planning and performance tuning. IOInsight ships as a virtual appliance that can be deployed in any vSphere environment and includes an intuitive web-based UI that allows users to choose VMDKs to monitor and view results.

Where does IOInsight help?

Customers may better tune and size their storage.
When contacting VMware Support for any vSphere storage issues, including a report from IOInsight can help VMware Support better understand the issues and can potentially lead to faster resolutions.
VMware Engineering can optimize products with a better understanding of various customers’ application behavior.

IOInsight captures I/O traces from ESXi and generates various aggregated metrics that represent the I/O behavior. The IOInsight report contains only these aggregated metrics and there is no sensitive information about the application itself. In addition to the built-in metrics computed by IOInsight, users can also write new analyzer plugins to IOInsight and visualize the results. A comprehensive SDK and development guide is included in the download bundle.

The fling works with vSphere 5.5 or above and can be downloaded at https://labs.vmware.com/flings/ioinsight.

Whitepaper on vSphere Virtual Machine Encryption Performance

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vSphere 6.5 introduces a feature called vSphere VM encryption. When this feature is enabled for a VM, vSphere protects the VM data by encrypting all its contents. Encryption is done both for already existing data and for newly written data. Whenever the VM data is read, it is decrypted within ESXi before being served to the VM. Because of this, vSphere VM encryption can have a performance impact on application I/O and the ESXi host CPU usage.

We have published a whitepaper, VMware vSphere Virtual Machine Encryption Performance, to quantify this performance impact. We focus on synthetic I/O performance on VMs, as well as VM provisioning operations like clone, snapshot creation, and power on. From analysis of our experiment results, we see that while VM encryption consumes more CPU resources for encryption and decryption, its impact on I/O performance is minimal when using enterprise-class SSD or VMware vSAN storage. However, when using ultra-high performance storage like locally attached NVMe drives capable of handling up to 750,000 IOPS, the minor increase in per-I/O latency due to encryption or decryption adds up quickly to have an impact on IOPS.

For more detailed information and data, please refer to the whitepaper

VMware Virtual SAN Stretched Cluster Best Practices White Paper

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VMware Virtual SAN 6.1 introduced the concept of a stretched cluster which allows the Virtual SAN customer to configure two geographically located sites, while synchronously replicating data between the two sites. A technical white paper about the Virtual SAN stretched cluster performance has now been published. This paper provides guidelines on how to get the best performance for applications deployed on a Virtual SAN stretched cluster environment.

The chart below, borrowed from the white paper, compares the performance of the Virtual SAN 6.1 stretched cluster deployment against the regular Virtual SAN cluster without any fault domains. A nine- node Virtual SAN stretched cluster is considered with two different configurations of inter-site latency: 1ms and 5ms. The DVD Store benchmark is executed on four virtual machines on each host of the nine-node Virtual SAN stretched cluster. The DVD Store performance metrics of cumulated orders per minute in the cluster, read/write IOPs, and average latency are compared with a similar workload on the regular Virtual SAN cluster. The orders per minute (OPM) is lower by 3% and 6% for the 1ms and 5ms inter-site latency stretched cluster compared to the regular Virtual SAN cluster.

Figure 1a. DVD Store orders per minute in the cluster and guest IOPS comparison

Guest read/write IOPS and latency were also monitored. The read/write mix ratio for the DVD Store workload is roughly at 1/3 read and 2/3 write. Write latency shows an obvious increase trend when the inter-site latency is higher, while the read latency is only marginally impacted. As a result, the average latency increases from 2.4ms to 2.7ms, and 5.1ms for 1ms and 5ms inter-site latency configuration.

Figure 1b. DVD Store latency comparison

These results demonstrate that the inter-site latency in a Virtual SAN stretched cluster deployment has a marginal performance impact on a commercial workload like DVD Store. More results are available in the white paper.