Excluding Backup Disk from Veeam

I came across this issue the other day whilst I was installing Veeam Backup & Replication 6 for a customer.  The issue was not so much about excluding a disk from the Veeam backup but excluding the Veeam backup repository disk from a backup.

This is the story of the situation, the reason for the issue and then the solution to the issue:

The Situation

We had just finished installing a new ESXi environment for the customer and were just configuring a Veeam backup.  The customer had an unusual requirement to split their OS disks and Data disks onto different speed disks… this is a little unusual but is perfectly valid.

They had Veeam installed on a virtual machine on the ESXi environment and had presented up a 2TB disk to the Veeam virtual machine as the storage drive for the backups, this was then going to be used as the Backup Repository.

The customer then explained that they wanted to backup the Veeam virtual machine (excluding the Backup Repository disk).  This seemed like a reasonable request and therefore we went through and configured the backup task and performed the first backup… the backup failed with the following error message:

Error: File <unspecified filename> is larger than the maximum size supported by the datastore <unspecified datastore>


The Reason

I’m not completely certain of the reasoning behind the error message but I believe that the issue is due to the configuration of the virtual disk and the way that VMware performs its Snapshots.  Within Veeam we had excluded the Backup repository disk from the backup as normal but obviously this meant that it was still part of the configuration on the virtual machine.  When Veeam performs its backups, it takes a snapshot of the virtual machine… but unfortunately, cannot choose which disks to be snapshotted and has to apply a snapshot to the whole virtual machine.  This meant that there was not enough space available on the datastore where the configuration files are stored to house the snapshot files and therefore the error message above appeared.


The Solution

I performed some investigation on the subject and was racking my brain about how to solve this issue and then remembered a feature of VMware that I knew about but hadn’t really used before.

To avoid the 2TB disk used for the backups being included in the snapshot I went through and enabled the option on the disk to make it ‘Independent’ and ‘Persistent’.  This excludes the disk from being snapshotted but makes sure that the data is still written directly to the disk.  The unfortunate thing is that you cannot make the change to the disk once it is attached to the virtual machine… the thing to do, is to remove the disk from the configuration on the virtual machine (making sure not to delete the disk).  Add the disk back to the configuration of the virtual machine… making sure that the ‘Independent’ and ‘Persistent’ options are selected… the next time that you run the backup, it will complete successfully excluding the larger disk.

About the Author


I have been in IT for the past 15 years and using virtualisation technologies for around the past 8 years. I started, as quite a lot of people do, working with PCs after playing with such iconic systems like the ZX81, ZX Spectrum and then progressing through 386s, 486s, Pentiums etc. After being headhunted at sixth form to work for a small company based around Hertfordshire, UK. I began working with small businesses and gaining a lot of hardware experience. Three years later, after helping to increase the size of the business, I needed to gain exposure to a larger environment to progress my own career. I joined a large manufacturing company around Electronic Test and Measurement which progressed my skills onto more PC work, hardware work and then onto Server Operating Systems. I progressed again onto a consultancy company based in Reading, UK. Initially working as an engineer performing hardware / software installations for larger companies contracted out to the consultancy company, I moved up into a Consultant position continuing my travel across the UK assisting and providing solutions to companies. I finally moved on again to my current position, working back in Hertfordshire, UK. Again working for a large manufacturing company, this time with over 50,000 users worldwide. I am responsible for the datacenter hardware, the storage environment, the vmware environment and also implementing their new Citrix XenApp farm. My days are busy but also productive, its a friendly environment and in my four years of being with the company, I have seen many changes in technology and infrastructure in use within the company. About the site I started this site as I had been thinking of having more of a presence on the web for a while. On a daily basis, I perform tasks and use tools that others may not use or may not think to do and therefore I thought that I would share some of these experiences and tips with others to help with their day to day work. Currently, my main focus of work is around VMware and Veeam Backup & Replication but hopefully as my tasks progress, I’ll be able to share useful bits of information about other areas of IT as well.

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