unknown device

i have a filesystem listed on /dev/vda1, and the used space is growing fairly steadily - it was at 419MiB free a few minutes ago.

i have no idea what is accessing this device, and i am not allowed to unmount or delete it. what can i do to track down this device. i have checked lsusb but it is not there, and it is not listed as the source for any of my shares.

your help is greatly appreciated!

bill

thanks gderf for responding.

first, this is omv running in a proxmox container.

physically on the server:

1x 1 TB USB drive for OS - not shared to OMV

4x 4 TB drives configured as RAID on OMV

when i ran lsusb, there were no devices on /dev/vda1

unfortunately, i am not very linux knowledgable, so do not know how to further investigate what this device is.

thanks again.