Ext3 has 30K directory limit inside one single directory and I needed to create ~180K.
Crap, I need another filesystem, which might be ext4, xfs or something like it. But I can't shutdown a production server or plug another disk. So I created one file which is big enough for my needs (let's say 100G):
Let's format the file:
Now, you can mount the file wherever you like:
$ mount -t ext4 my_ext4_blockfile new_disk
System will mount it with help of loop device, you might check it via mount command.