Why am I I/O bound for writing to MySQL when writing 5KB/sec?
I am looking for some help with someone with MySQL expertise. I don't need an exact solution - just some ideas and places to look for optimizing.

A little bit about the problem:

 -  I need to insert a large number of rows into an InnoDB tables. 
 - Each table has only one index (which is also the primary key)
 - Each row has about 1KB of data in it.
 - I am using Load Data INFILE queries of about 5000 rows at a time.
 - I am using 8 threads for the writes (each writing separate data ).

Ok, so with these characteristics, I am getting a throughput of around 1 million rows per hour written to the DB. This is about 1 GB of data or ~5KB/sec, based on the upper-end of how much data is in a row. 

However, when I look at my machine statistics, I notice the I/O graph for disk writes flatlines at about 20 MB / sec, which suggest that I am I/O bound. (The CPU graph also shoots to 100%, but about 90% of that is iowait). So, my question is why would MySQL be writing about 20 MB / sec of data to disk, when the amount of data sent through queries is about 5 KB / sec. 

I am guessing the discrepancy is due to log files, temp tables and transaction doubling - but I am wondering why this ratio is more than 100:1? And how can shrink this ratio to something more reasonable? What sort of internal variables are causing MYSQL to write out so much data to disk instead of storing it in memory? For instance, I have already set innodb_buffer_pool_size = 12G, max_heap_table_size = 8G and tmp_table_size = 6G in an attempt to make MySQL use more memory instead of disk - but still the same result.

I appreciate any help and advice you can give me!
Why am I I/O bound for writing to MySQL when writing 5KB/sec?
===

I am looking for some help with someone with MySQL expertise. I don't need an exact solution - just some ideas and places to look for optimizing.

A little bit about the problem:

 -  I need to insert a large number of rows into an InnoDB tables. 
 - Each table has only one index (which is also the primary key)
 - Each row has about 1KB of data in it.
 - I am using Load Data INFILE queries of about 5000 rows at a time.
 - I am using 8 threads for the writes (each writing separate data ).

Ok, so with these characteristics, I am getting a throughput of around 1 million rows per hour written to the DB. This is about 1 GB of data or ~5KB/sec, based on the upper-end of how much data is in a row. 

However, when I look at my machine statistics, I notice the I/O graph for disk writes flatlines at about 20 MB / sec, which suggest that I am I/O bound. (The CPU graph also shoots to 100%, but about 90% of that is iowait). So, my question is why would MySQL be writing about 20 MB / sec of data to disk, when the amount of data sent through queries is about 5 KB / sec. 

I am guessing the discrepancy is due to log files, temp tables and transaction doubling - but I am wondering why this ratio is more than 100:1? And how can shrink this ratio to something more reasonable? What sort of internal variables are causing MYSQL to write out so much data to disk instead of storing it in memory? For instance, I have already set innodb_buffer_pool_size = 12G, max_heap_table_size = 8G and tmp_table_size = 6G in an attempt to make MySQL use more memory instead of disk - but still the same result.

I appreciate any help and advice you can give me!