Sentinel 2 Problem on target product processing

I want to mosaic 6 tiles for my study area. For that, I had resampled all the image tiles to 10m resolution. In order to mosaic all the tiles, I mosaiced first 3 tiles at at one time and another 3 tiles second time due to the low computational requirements of my computer. My device specifications are processor: intel core i5, speed:1.60-2.11 GHz, Ram: 8GB, System type: 64 bit OS, Windows 10 Home edition. Finally, to mosaic those 2 mosaiced tiles(mosaic 3 tiles(1)+mosaic 3 tiles(2)), the following error is occurred.

"A problem occurred the target product processing
Type: Operator Exception
Message: Not able to write product file ‘G:\SA1_Resampled\mosaicUltimate.dim’

please assist me in this regard
Thanks Hari.

Maybe SNAP log file can provide more details. It’s the most recent messages.log file found in the location from SNAP → Help menu → Show Log Directory.
Maybe you just run out of space, this is why writing the target product couldn’t be accomplished.

I noticed the drive G used for the target product, is this an external disk?