Updating VMware Virtual SAN HCL database offline

VMware offers certified compatibility guides which list System, I/O, Storage/SAN and Backup compatibility with VMware Infrastructure and previous versions of VMware ESX Server. VSAN Health Check leverage VMware Compatibility Guide database for various health checks stored on vCenter Server in place of VMware website.

VMware ships a copy of VMware compatibility guides database can be used for HCL Checks which was current when released. The VMware compatibility Guides database becomes outdated with time because of new certification with partners keep getting added to VMware Compatibility Guide database.  Hardware vendors regularly update their drivers and VMware adds certification for them. Therefore, it is critically important to keep the local copy up-to-date.

In one of my earlier post, I covered VSAN Hardware Compatibility list checker a very nice VMware Fling to verify the VSAN underline hardware.

VMWare VSAN HCL database can be automatically from VMware website if vCenter server can connect to Internet directly or via proxy. If you don’t have direct or proxy internet access, VMware VSAN HCL database can be downloaded manually and uploaded to vCenter Server. To download VMware VSAN HCL database manually, open the below URL in a web browser and save the content in a file with JSON extension.


Once you have VSAN updated HCL database JSON file, you can upload the same to vCenter Server using Web Client.

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In this post we covered the steps to update VSAN HCL database offline. Thanks for Reading. Be social and share it in social media, if you fee worth sharing it. Happy Learning 🙂


Configuring Space Efficiency Technologies in VSAN 6.2

Virtual SAN 6.2 introduces space efficiency features optimized for modern all-flash storage. You can use space efficiency techniques to reduce the amount of space for storing data. Space efficiency features available in VSAN 6.2 are :

  • Deduplication and Compression on a Virtual SAN Cluster.
  • RAID 5 and RAID 6 erasure coding using Failure tolerance method policy attribute on VMs.

In this post, we will be covering the configuration of both the space efficiency features.

Deduplication and Compression

Enabling deduplication and compression can reduce the amount of physical storage consumed by as much as 7x. Environments with highly-redundant data such as full-clone virtual desktops and homogenous server operating systems will naturally benefit the most from deduplication. Deduplication and compression is a single cluster-wide setting that is disabled by default and can be enabled using a simple drop-down menu. This process does not incur virtual machine downtime and can be done online. The compression algorithm is applied after deduplication has occurred just before the data is written to the capacity tier.

When you enable deduplication and compression on a Virtual SAN all-flash cluster, redundant data within each disk group is reduced. Deduplication removes redundant data blocks, whereas compression removes additional redundant data within each data block. You can enable deduplication and compression as a cluster-wide setting, but they are applied on a disk group basis. The amount of storage reduction from deduplication and compression depends on the type of data stored and the number of duplicate blocks.

Deduplication and Compression Design Considerations :

  • Only available on ALL Flash Disk Groups.
  • On-disk format version 3.0 or later is required.
  • Storage-claiming method should be set to manual. Storage-claiming method to automatic after deduplication and compression has been enabled.
  • Capacity overhead for deduplication and compression is approximately five percent of total raw capacity.
  • Using policies with 100 percent proportional capacity reservations can make deduplication and compression less efficient.
  • Virtual SAN can eliminate duplicate data blocks within each disk group, but not across disk groups.

Procedure to configure Deduplication and Compression

Login to vSphere Web Client. Select the Cluster –> Manage –> Settings. Click on Edit to enable Deduplication and Compression.

Screenshot-18Select Enabled from the drop down list.Screenshot-19

Screenshot-20Once Deduplication and Compression is enabled. Virtual SAN performs a rolling reformat of every disk group on every host.
Screenshot-21It will take some time to get the duplication blocks of data removed. You can check the results of deduplication and compression by viewing the Deduplication and Compression Overview in the Virtual SAN Capacity monitor.


Configuring RAID 5 or RAID 6 Erasure Coding

You can use RAID 5 or RAID 6 erasure coding to protect against data loss and increase storage efficiency with same level of data protection as provided in RAID 1, while using less storage capacity.


Below is the Host Requirements Based on Failure Tolerance Method. Due to the host or fault domain requirements of the RAID-5/6 (Erasure Coding) rule, Virtual SAN Stretched Cluster and 2 node configurations are not supported.


In VSAN 6.2, RAID5 and RAID6 technologies, there is no “parity host” and data parity can be on any capacity device.


RAID 5 and RAID 6 Design Consideration

  • On-disk format version 3.0 or later is required to support RAID 5 or RAID 6.
  • RAID 5/6 is not supported on stretched clusters.
  • RAID 5 or RAID 6 erasure coding is available only on all-flash disk groups.
  • Additional space savings by enabling deduplication and compression on the Virtual SAN cluster.

Procedure to configure RAID 5 and RAID 6.

RAID 5 and RAID 6 can be made available using VSAN policy. If FTT = 1 is configured in VSAN Policy, RAID 5  will get configure on the Virtual Machine disk.


Assign the VSAN Policy to the Virtual machine.



If FTT = 2, RAID 6 will be get configured on Virtual Machine disk.



This concludes the configuration of VSAN Storage efficiency techniques in VSAN 6.2. I hope this is informative for you. Thanks for reading !!!. Be social and share it in social media, if you feel worth sharing it.




Virtual SAN 6.2 released with vSphere 6.0 U2

With the release of vSphere 6.0 U2, VMware release VSAN 6.2. Virtual SAN 6.2 introduces the following new features and enhancements :

  • Deduplication and compression. Virtual SAN 6.2 supports deduplication and compression to eliminate duplicate data. This technique reduces the total storage space required to meet your needs. When you enable deduplication and compression on a Virtual SAN cluster, redundant copies of data in a particular disk group are reduced to single copy. Deduplication and compression are available as a cluster-wide setting on all-flash clusters.
  • RAID 5 and RAID 6 erasure coding. Virtual SAN 6.2 supports both RAID 5 and RAID 6 erasure coding to reduce the storage space required to protect your data. RAID 5 and RAID 6 are available as a policy attribute for VMs in all-flash clusters. You can use RAID 5 in clusters with at least four fault domains, and RAID 6 in clusters with at least six fault domains.
  • Software checksum. Virtual SAN 6.2 supports software-based checksum on hybrid and all-flash clusters. The software checksum policy attribute is enabled by default on all objects in the Virtual SAN cluster.
  • New on-disk format. Virtual SAN 6.2 supports upgrades to new on-disk virtual file format 3.0 through the vSphere Web Client. This file system provides support for new features in the Virtual SAN cluster. On-disk format version 3.0 is based on an internal 4K block size technology, which provides improved efficiency, but can result in reduced performance if the guest operating system I/Os are not 4K aligned.
  • IOPS limits. Virtual SAN supports IOPS limits to restrict the number of I/O (read/write) operations per second for a specified object. When the number of read/write operations reaches the IOPS limit, those operations are delayed until the current second expires. The IOPS limit is a policy attribute that you can apply to any Virtual SAN object, including VMDK, namespace, and so on.
  • IPv6 Support. Virtual SAN supports IPv4 or IPv6 addressing.
  • Space reporting. The Virtual SAN 6.2 Capacity monitor displays information about the Virtual SAN datastore, including used space and free space, and provides a breakdown of capacity usage by different object types or data types.
  • Health service. Virtual SAN 6.2 includes new health checks that help you monitor the cluster and enable you to diagnose and fix problems with the cluster. If the Virtual SAN health service detects health issues, it triggers vCenter events and alarms.
  • Performance service. Virtual SAN 6.2 includes performance service monitors with cluster-level, host-level, VM-level, and disk-level statistics. The performance service collects and analyzes performance statistics and displays the data in a graphical format. You can use the performance charts to manage your workload and determine the root cause of problems.
  • Write-through in-memory cache. Virtual SAN 6.2 improves virtual machine performance by using a host resident write-through read cache. This caching algorithm reduces read I/O latency and reduces Virtual SAN CPU and network usage.


The table below shows you the new features of 6.2 together with the existing features of 6.1.



I hope this is informative for you. Thanks for reading !!!. Be social and share it in social media, if you feel worth sharing it.


VSAN Hardware Compatibility List Checker

VMware Labs recently released a new fling VSAN Hardware Compatibility List Checker to verify if the installed hardware components are on the HCL list. It also verify if a storage controller on a server is on VMware HCL. You can download the fling from here.

System Requirements

  • Windows: XP, 7, 8, 10, Server 2008, 2012
  • Browser: IE 8 and above

Network Requirements

  • HTTPS/443 access to ESXi hosts (interacting with hostd)
  • TCP/5989 access to ESXi hosts (CIM service secure)
  • Internet HTTP/80 access to http://partnerweb.vmware.com/service/vsan/all.json (optional)

ESXi Host Requirements

  • ESXi 5.1.x, 5.5.x, 6.x are supported
  • Direct access to the hostd service with username and password
  • CIM service (secure) running on port 5989
  • CIM provider for HP or LSI controller

How does it works ?

  • Download the fling and extract to a folder.
  • Fling will check for installed SSL Certificate on host. In case of Self Signed Certificate run the fling with –noSSLVerfiy option

hclCheck.exe –noSSLVerify

VSAN Checker

  • Provide the hostname / IP of ESX Host and root password.
  • Once completed generated report will be be saved in the same extracted folder. Open the the report in browser.


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Deploying VSAN 6.1 Stretched Cluster

In VMware Virtual SAN 6.1, VMware introduced a new feature called VMware Virtual SAN Stretched Cluster with specific configuration implemented in environments where disaster / downtime avoidance is a key requirement. In VSAN Stretched cluster user deploy 2 active / active sites with equal number of hosts along with a witness host deployed in third site. A Maximum of three sites (two data and one witness) are supported. Minimum supported configuration is (1 + 1 + 1) 3 nodes. Maximum supported configuration is (15 + 15 + 1) 31 nodes. Virtual Machine deployed in VSAN Stretched cluster will have one copy of its data in Site A and another copy in Site B. The only supported disk format for VSAN Stretched Cluster is v2. Disk format should be upgraded to v2 before implementing.

vSphere and VSAN Edition

VMware introduced new VSAN Advanced Editions in VSAN 6.1 that will include both All – Flash and Stretched cluster functionality. DRS is a desirable functionality in VSAN stretched cluster deployment but as DRS handles the initial placement of the Virtual Machines as well as help with locating virtual machines to their correct site when a site recovers after failure.


  1. VSAN Advanced license.
  2. vCenter Server Instance.
  3. A Witness Host to host witness components. A witness host can be virtual appliance or a physical host. It is important that witness host is not added to the VSAN Cluster. The witness host is selected during VSAN stretched cluster creation.
  4. VMware recommends VSAN communication between the data sites to be over stretched L2. In the event of a failure, the VMs will not require a new IP on the remote site. However L3 between data sites are also supported. The main concern with L3 is the virtual machine network. There is no easy, automated to re-IP the guest OS to the network on the other data site after fail-over.
  5. VMware requires VSAN communication between data sites and witness site to be over L3.
  6. Maximum latency should not be more than 5ms between Data Sites or < 2.5ms one way.
  7. Maximum latency should not be more than 200ms between Data Site and Witness Site however it latency requirement is also dependent on cluster size. VMware recommends 200ms as acceptable latency for VSAN Cluster configuration up to (10 + 10 + 1). For configuration greater than ( 10 + 10 + 1), VMware recommends a latency of less than or equal to 100 milliseconds.
  8. VMware recommends a minimum of 10Gbps bandwidth between Data Sites.
  9. Bandwidth between Data nodes and Witness node should not be less than 50 – 100 Mbps.

In this video, I demonstrated how to configure a VSAN Stretched cluster and VMware recommended configurations for VSAN Stretched Cluster.

I hope this is informative for you. Thanks for reading !!!. Be social and share it in social media, if you feel worth sharing it.