We allow you unlimited bandwidth transfer per month at no cost. Sharetru's customers consume a lot of bandwidth and this is our single largest cost of operation. The typical FTP site turns over its data storage regularly — often daily or even multiple times per day. Every file you send to someone is transferred at least twice (once to upload and once to download). This usage affects our costs and it is directly related to storage.
Second, Sharetru does not use “cheap” storage media or cloud object storage such as S3 from AWS. Our hard drives have high read-write performance. Our RAID arrays stripe and mirror (replicate) every byte across multiple drives within the array for reliability and for recovery from hard drive failures. We also have to keep “hot spares” in all our storage systems to automate recovery.
Third, we back up every file you put on the FTP site and we keep 7 days of backups minimum. This means we maintain backups that take up several times the amount of storage you are paying for on the FTP server itself.