is it possible to replace smaller capacity disk with larger one on DMXs (is there any primus solution or some documents about this)?
This would not be supported, assuming you are talking about a normal drive replacement but using a bigger drive than what is installed. The replacement script would fail when it sees the new drive is different than the one being replaced. Of course the PSE Lab and Engineering have ways to make things work by skipping checks but this would typically not be done.
When a replacement drive is ordered a compatibility matrix is referenced to provide a list of compatible parts. Size may not be the only difference in the technology of the replaced drive. Installing the incorrect drive could have effects later on when other drives need to be ordered for further replacements or upgrades. Installing a different type of drive than is in the bin file could have implications as well.
Actually larger disks are used as replacements quite frequently for smaller disk drives based on availability and drive types being end of lifed.
I would not recommend using a drive, or any other part, without a procesure or documentation stating that it is an acceptable replacement. If the original part is no longer available then an alternate part will need to be used but the supporting documentation should have been updated accordingly.
As far as using this as a means to upgrade it would be a long process. You would have to do a drive replacement on each drive you wanted to swap out with a drive that is compatible (architecture and speed). once all the drives are swapped you do need a bin file change to change the type of drive in the bin file. This doesn't affect the drive it increases the number of tracks per drive to the correct amount.
I was not aware of how common this is now. Shortly after this discussion I came across other references to the phasing out of smaller drives (just by chance, not looking for it, strange when that happens). Thanks for enlightening me!
My point in my original response was meant to say that we would not simply grab a larger drive because the current one is not available "at the moment." That is true, and even when a different size drive is used, there are requirements. But the response was probably a bit too restrictive.