logo Vertical Backup

A new network and cloud backup tool for VMware vSphere (ESXi)
Fast, deduplication, encryption, live backup, schedule and email
Works with free or licensed ESXi


 A New Way of Backup

Many existing ESXi backup tools supporting versioned backup require frequent full backups, with incremental backups in between. This makes it impossible to delete individual backups, and restoration from an increment backup becomes slow because it has to start at a full backup with subsequent incremental ones applied as patches.

Vertical Backup does not require full backups after the initial one. Every backup is incremental by nature since only new blocks are uploaded. At the same time, each backup also appears to be a full backup, such that any backup can be individually deleted without affecting others, or independently restored without the need to go through a long chain of other backups.

 The Highest Degree of Deduplication

Vertical Backup is capable of deduplicating not only identical blocks in the same virtual machine image, or identical blocks in different images on the same ESXi host, but also identical blocks in different images on different ESXi hosts. This greatly saves storage space and improves backup speed in scenarios where multiple virtual machines based on the same initial image run on different hosts, or where a virtual machine is replicated from one host to another.

 Cloud Support

Designing a deduplication algorithm to support features such as incremental backup, cross-host deduplication, and independent deletion and restoration is not a hard problem, if a dedicated deduplication storage server is available. What is hard, however, is to allow the algorithm to work with general-purpose file storage backends having no notion of deduplication, while at the same time not giving up any of these essential features. We solved this hard problem with a new deduplication algorithm called Lock-Free Deduplication.

The implication is that Virtual Backup can literally turn any network or cloud storage allowing only basic file operations into a sophisticated deduplication server. Currently 5 storage backends are supported, including local or NFS-mounted disk, SFTP server, Amazon S3 storage, Wasabi, Microsoft Azure, and Backblaze B2. New storage backends will be added as user demand grows.


In designing Vertical Backup, we thought long and hard to squeeze out every bit of performance. The end result is a high-performance backup tool that makes hourly live backup feasible even with limited bandwidth and without Changed Block Tracking support.

The following table compares speeds of backing up a 16 GB Linux virtual machine on a free ESXi over a 1Gbps network connection. Whereas initial backups with Vertical Backup are comparable to or even slightly faster than a direct copy using the native VMWare tool (vmkfstools), subsequent backups are more than twice as faster.

Method Backup Time Speed
vmkfstools over NFS 114s 143.5MB/s
Vertical Backup over NFS (initial) 120s 135.7MB/s
Vertical Backup over NFS (subsequent) 53s 304.4MB/s
Vertical Backup over SFTP (initial) 113s 144.6MB/s
Vertical Backup over SFTP (subsequent) 54s 299.9MB/s

 Interoperability with Duplicacy

Vertical Backup is not a completely new backup tool. It is a reimplementation of Duplicacy, a cross-platform general purpose file backup tool. As a result, backups created by Vertical Backup can be opened and managed by Duplicacy on Windows, macOS, Linux, etc. In addition, the source code of Duplicacy is available, allowing interested users to understand how backups are stored and make sure that backups can always be restored by programs compiled from source code.

Duplicacy supports many more cloud storage backends, such as Google Cloud Storage, Microsoft OneDrive, Google Drive, Dropbox, and hubiC. It is possible to use Duplicacy to copy backups created by Vertical Backup to any of these cloud storages.


 Simple Licensing

Vertical Backup does not rely on the VADP API, so it works equally well on free or licensed ESXi. The licensing fee is fixed at $99 per host per year (or $20 for personal use), regardless of the ESXi version, the number of CPUs, the amount of physical memory, the number of virtual machines, etc.

Vertical Backup has been tested on ESXi 5.1, 5.5, 6.0, 6.5, and 6.7. Due to an unexpected snapshot locking change introduced by VMware, on ESXi 7.0 Vertical Backup cannot back up a virtual machine when it is running.

We are now offering free 30-day trial program during which all features are fully functional. Simply follow the instructions in the User Guide to download the software. A 30 day trial license will be automatically downloaded when the backup command is performed for the firs time.