Backup virtual disks (qcow2 format)

[oscar]

I am running inside a docker container.
The host (a QNap NAS) is also running several virtual machines using qcow2 format for the virtual disks.

Can duplicacy backup the very large IMG files of the virtual disks?
What are some good practices for it?

Thanks,

Oscar

[jiahao_xu]

IMHO duplicacy should handle these large qcow2 image just fine, though it might take a lot of ram in the latest release if these files are extremely large.

Though gchen is working on a new release that uses less ram, it might take a while for the new release to come out.

Edit:

I was wrong about the memory usage part.

As @gchen has pointed out in the reply below, the memory usage of duplicacy is depended on number of files, not size of files.

[oscar]

My Nas has 64 Gb RAM with only 32 gb used by the system (including the vms) , so it should be fine correct?

Can it handle these files while the files are being used by running virtual machines?

[jiahao_xu]

I think 32GM ram is more than enough for duplicacy.

Can it handle these files while the files are being used by running virtual machines?

No, you have to create a snapshot of these files, either by using qemu/kvm’s builtin snapshot capability, or by stopping the vm and create a copy of these images on disk, resume thse vm and back these copied files up.

[Droolio]

You’ll probably also want to initialise the Duplicacy storage with fixed-sized chunks for this type of data (scroll down to ‘Fixed Size Chunking’):

Chunk size details

Duplicacy adopts a unique pack-and-split method to split files into chunks. First, all files to be backed up are packed together, in an alphabetical order, as if it were building an imaginary tar file. Of course, this is only conceptual, otherwise Duplicacy would have quickly run out of memory in most use cases. This imaginary tar file is then split into chunks, using a variable size chunking algorithm. The default settings of the init command would generate chunks that are 4M bytes on avera…

[gchen]

@jiahao_xu

IMHO duplicacy should handle these large qcow2 image just fine, though it might take a lot of ram in the latest release if these files are extremely large.

Extremely large files won’t cause high memory usage – it is the number of files that determines the memory usage.

[jiahao_xu]

Thanks for pointing that out.

I’ve edited my reply to correct it.