VSAN 7 U1 on blogs.hareeshkg.com

vSAN 7 U1 Component Placement

Sun, 31 Jan 2021 18:01:54 +0000

vSAN 7 U1 brought in significant changes to its method of creating components especially for objects which are larger than 255GB. This change was brought in adapt to minimum slack space requirements which is significantly lower than all previous versions of vSAN.

I highly encourage you to read thru blog articles “Understanding vsan Objects and Components” and “Understanding VM-Storage-Policies” as the basics about object/component placement are discussed in those specific blogs.

vSAN Scrubber changes 7.0U1c

Wed, 30 Dec 2020 19:04:48 +0000

vSAN Scrubber is a background operation at DOM owner. Scrubber performs detection (scrub) and fixing (recover) of checksum and IO errors.

Mostly Checksum errors and I/O errors which are seen in vSAN environment is due to medium errors against the physical capacity disks where the data is persisted. These errors don’t surface until we try to read the object from both mirrors (in case of raid-1 objects). We might always be performing reads on a single mirror especially in case of Stretched cluster where site affinity is set to either preferred site or secondary site to avoid cross site traffic.

vSAN 7 Update 1 FastBoot – Feature Walkthrough

Sun, 20 Sep 2020 09:03:49 +0000

vSAN hosts reboots when compared to regular ESXi hosts generally take longer due to its log structured system to capture and track all the modifications occurring at the write buffer / Cache Disks, vSAN uses an in-memory table to track changes to the blocks, LBA tables, bitmaps etc. This in memory table is always lost when a vSAN host is rebooted. At the time of boot vSAN takes a long time to recover these entries from each of the disk groups to reconstruct the in-memory table, the time spent to perform this recovery generally depends on the size of LLOG/PLOG that needs to be recovered from each of the disk groups. vSAN 7.0U1 / vSAN 7 Update 1 performs a “save and restore” workflow to rebuild vSAN in-memory metadata allowing “Faster vSAN Host Restarts” or Fastboot.

Enhanced Durability Maintenance Mode – Feature Walkthrough

Wed, 16 Sep 2020 09:05:00 +0000

What is Durability Component?, Lets consider a scenario of a three node vSAN cluster, where one of the host is placed in maintenance mode. All the vSAN objects will now be accessible with “Reduced Redundancy” mode which means that any failures that are encountered on the surviving two nodes will lead to data unavailability and sometimes data loss situation even with all recovery efforts from a support perspective.

Whenever there is one or more hosts placed in maintenance mode with ensure accessibility, vSAN 7 Update 1 introduces a method to write new changes by spawning a new component called “Durability Component“. Since new changes for the objects that are being written to this “Durability Component” if we were to encounter a failure on one of surviving host, exiting maintenance mode on the host which has stale components will sync the changes with the Durability Component and becomes an active component again and the Durability Component is automatically cleaned up by the CLOM service on that node . This helps ensure the durability of the changed data in the event that the one host holding the updated object replica failed during this maintenance window

HCI Mesh™ -Feature Walkthrough

Wed, 16 Sep 2020 08:58:45 +0000

**HCI Mesh

** is one of the new feature that is introduced with vSAN 7 Update 1 release. HCI Mesh

provides disaggregation of compute and storage by allowing vSAN customers to share vSAN datastores between two or more clusters. vSAN administrators can setup a relationship between two to five clusters and allow these clusters to borrow/share vSAN datastore capacity.

We can achieve better compute and storage utilization across the datacenter and avoid unnecessary purchase of hardware per cluster. Example : VM hosted on cluster-1 can have all of its disks and namespace provisioned from a different cluster within the same datacenter, allows vSphere administrators to do a regular vMotion (not SvMotion) between one or more clusters which are part of this **HCI Mesh

** topology. This feature uses native vSAN VMKernel adapter and existing RDT protocol to communicate in the mesh topology with other cluster vSAN nodes which is simplistic and efficient.

Shared Witness – Feature walkthrough

Wed, 16 Sep 2020 08:26:01 +0000

vSAN 7 Update 1 now gives us high efficiency to this two node “Shared Witness” topology by allowing vSAN administrators to use a single shared witness for up to 64 two node vSAN clusters and hence reduces witness server/appliance footprint/resource usage in the central datacenter. The new UI for the witness appliance under Cluster->Monitor->vSAN->Two Node Clusters.

Two-Node vSAN ROBO cluster configuration was introduced some time back with vSAN 6.2 release couple of years back, this architecture was used primarily in large number of small branch offices, retail sites, IOT etc. All two node vSAN cluster configuration always needed a dedicated witness appliance for each of its deployment until vSAN 7. This means that there was a large footprint of witness appliances in the central site which hosts witnesses for all of its retail two node ROBO sites.

IOInsight vSAN 7.0 U1 – Feature walkthrough

Wed, 16 Sep 2020 06:38:07 +0000

This blog article is a feature walkthrough on “vSAN 7 Update1 IOInsight” and understand how this can help us to approach/investigate performance related issues on VMs running on vSAN.

IOinsight has been available in the VMware-Flings community market place for quite sometime. vSAN engineering team has now included IOInsight natively with vSAN Performance services with this latest release of vSAN7 Update 1. This provide deep dive performance metrics and insights on individual VM and VMDK level, so that this data can be used to mitigate performance related issues on specific VMs and VMDKs.

Technical Overview – vSAN 7 Update 1

Tue, 15 Sep 2020 06:16:40 +0000

vSAN 7.0 U1/ vSAN 7 Update1 is one of the biggest release for vSAN in last couple of years, there is a long list of new features that are added/released with this version. This blog article talks briefly on all the important features for vSAN7 Update1 / vSAN 7.0 U1. I will be covering all the features exclusively on newer dedicated posts for each of the features.

-1 **VMware HCI Mesh

** -vSAN 7.0 U1

vSAN 7 U1 Compression-Only – Feature Walkthrough

Tue, 15 Sep 2020 00:30:00 +0000

In this blog article we will look at the vSAN 7 U1 Compression-Only feature ,its benefits and how it fares with other space saving features on the previous releases of vSAN.

I have been asked by a lot vSAN users about vSAN only allowing us to enable Deduplication and Compression together as feature in all the releases since vSAN 6.x. Finally VMware made this announcement for vSAN compression only mode is here with vSAN 7 Update1 we can totally eliminate the additional overheads for Deduplication when using Compression-Only yet get good space savings. Let dive straight into key difference between Deduplication & Compression vs Compression-Only.