Something to say about number of files per folder is.
A lot of hosts will limit how many files per folder. Or at least used to.
Meaning you have say 15000 files but when you ftp you only see say 9000.
FAT32:
Maximum number of files: 268,173,300
Maximum number of files per directory: 65,535
NTFS:
Maximum number of files: 4,294,967,295
ext2:
Maximum number of files: 1,000,000,000,000,000,000
Maximum number of files per directory: ~1.3 × 100,000,000,000,000,000,000 (performance issues past 10,000)
ext3:
Maximum number of files: min(volumeSize / 8,192, numberOfBlocks)
ext4:
Maximum number of files: 4,294,967,295
Maximum number of files per directory: 10 million approximately (can be extended with large_dir feature)
source:
https://stackoverflow.com/questions/466521/how-many-files-can-i-put-in-a-directoryThough, when you say you only see 9,000 files in the directory, what you may be referring to is
How many How to Increase FTP Visible File LimitsBy default, the FTP server on the cPanel set a limit to the number of files displayed through an FTP client. It is usually 9,000, if you wish to view more than 9,000 files through your FTP server, then you can follow-up this quick tutorial.
continued at:
https://www.interserver.net/tips/kb/how-to-increase-ftp-visible-file-limits/
