How to create 10GB blast database

Hello.

I want to create a database for local blast but fasta file with reads is 9Gb. So i want from this file to create only one database for the blast and not many files. So i put -max_file_sz argument as you can see above, but it creates many files of 2.1GB. How can i create only one database file ? Should i merge them later ?

Thank you.

Here is the command i use.

makeblastdb -in /mnt/usb/sra/merged.fasta -max_file_sz '10GB' -dbtype nucl -out /mnt/usb/sra/merged_db