Question: ***SOLVED (09.08.19)***:
**I was trying to save to hard drives with Fat32 file system, which has wont save files >4Gb. Reformatted the hard drive, and the files downloaded. Thank you for everyone' help!**

I keep having issues when downloading datasets with SRA.
This dataset I tried to download below is about 16Gb and it seems to fail after 3-4Gb downloads.
Error says **There is not enough space on the disk.(112)**, but I have it downloading on a 1Tb hard drive. Any suggestions?

C:\Users\USER\Downloads\sratoolkit.2.9.6-1-win64\bin>prefetch.exe -O "F:\ProjectSRAFiles" -X 100G -v SRR#

2019-09-05T19:10:10 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to www.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-05T19:10:11 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-05T19:10:11 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to sra-download.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-05T19:10:11 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-05T19:10:11 prefetch.2.9.3: 1) Downloading 'SRR#'...
2019-09-05T19:10:14 prefetch.2.9.3: Downloading via https...
2019-09-05T19:10:14 prefetch.2.9.3: https://sra-download.ncbi.nlm.nih.gov/traces/sra61/SRR/006699/SRR# -> /f/ProjectSRAFiles/SRR#.sra.tmp.7523.tmp
2019-09-05T19:10:14 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to sra-download.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-05T19:10:14 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-05T19:13:16 prefetch.2.9.3 err: unknown while writing file within file system module - error writing system file - There is not enough space on the disk.(112)
2019-09-05T19:13:16 prefetch.2.9.3 int: unknown while writing file within file system module - Cannot KFileWrite: /f/ProjectSRAFiles/SRR#.sra.tmp.7523.tmp
2019-09-05T19:13:18 prefetch.2.9.3: 1) failed to download SRR#

**UPDATE (09.06.19)**:
Now with aspera fasp download, I am not even getting an error. Just a message that the download fails after downloading only ~4.5Gb of the data. I have tried a brand new hard drive, and it is the same problem so I don't think it is an issue of file size.

USER-MacBook-Pro-2:ncbi USER$ prefetch -v SRR#

2019-09-06T15:34:36 prefetch.2.9.3: Using '/Users/USER/Applications/Aspera Connect.app/Contents/Resources/ascp'
2019-09-06T15:34:36 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to www.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-06T15:34:36 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-06T15:34:36 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to sra-download.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-06T15:34:36 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-06T15:34:37 prefetch.2.9.3: KClientHttpOpen - connected from 'IP ADDRESS' to www.ncbi.nlm.nih.gov (IP ADDRESS)
2019-09-06T15:34:37 prefetch.2.9.3: KClientHttpOpen - verifying CA cert
2019-09-06T15:34:37 prefetch.2.9.3: 1) Downloading 'SRR#'...
2019-09-06T15:34:37 prefetch.2.9.3: Downloading via fasp...
/Users/USER/Applications/Aspera Connect.app/Contents/Resources/ascp /Users/USER/Applications/Aspera Connect.app/Contents/Resources/ascp -i /Users/USER/Applications/Aspera Connect.app/Contents/Resources/asperaweb_id_dsa.openssh -pQTk1 -l 450m dbtest@sra-download.ncbi.nlm.nih.gov:data/sracloud/traces/sra61/SRR/006699/SRR# /Volumes/USER/CTAProjectSRAFiles/ncbi/public/sra/SRR#.sra.tmp.16642.tmp
SRR#
2019-09-06T15:46:15 prefetch.2.9.3: fasp download failed
2019-09-06T15:46:15 prefetch.2.9.3: 1) failed to download SRR#

Answer: I was trying to save to hard drives with Fat32 file system, which has wont save files >4Gb. Reformatted the hard drive, and the files downloaded. Thank you for everyone' help!