index for large .fastq file

I am trying to index a large .fastq file (~700GB) by `nohup sga index -a ropebwt --no-reverse -t 6 -vvv TT2.fastq &`, however, the job in the server disappeared suddenly without any returned files, or sometimes it just returned a .bwt.tmp file only. Is it because the .fastq file too large for my server to handle or did miss anything before indexing ? Thank you very much 

