On Tue, 11 Oct 2022 19:50:20 +0200, "Carlos E. R." <robin.listas@telefonica.net> wrote:
On 2022-10-11 08:54, Robert Webb wrote:
On Mon, 10 Oct 2022 21:16:23 -0700, Lew Wolfgang <wolfgang@sweet-haven.com> wrote:
On 10/10/22 19:39, Robert Webb wrote:
Can you connect all the destination disks at once, and issue a single copy command to write all the files? And the files not being split.
Yes, the main purpose of mergerfs is to have a whole set of disks active and to appear as one filesystem hierarchy. Each of the files exists whole, as one file in the native filesystem of an individual disk. The copy command would think everything is normal, usually, while mergerfs would be deciding to which disk each particular file gets written, according to a configurable policy. Things can get complicated for general filesystem use or if you just collect a bunch of independently written disks into a union set. For instance, multiple disks could have a file at the same path, and then mergerfs has to choose the one to present, according to some policy. But, the use case of copying a hierarchy onto a set of disks means that there is no path duplication (of files. The same directory may appear on multiple disks), and after a disk fills up, you are done with those files (because you know that those paths will not be written to, or read, again) and the disk can be unmounted. So you can run the process with just one or two disks mounted at a time, or with the whole set. But, you may not be able to change the set of disks in the union during a single copy command, or maybe you can. IDK. As far as I can tell, mergerfs does not have an idea of a complete set for the union filesystem, other than the sum of whatever disks are included at any moment.
The set of destination disks could be connected simultaneously if done using USB3.
The advantage would be not needing to be there to change the disks; just issue a single command and have the copy process run for hours or days, undisturbed. -- Robert Webb