ZFS-lighttpd2-sendfile, too high IO

[Bob Friesenhahn]

On Mon, 12 Sep 2011, Laszlo KAROLYI wrote:

> But does this explain the 4-5mbyte/s reads when having a 15mbit/s network load?

There are only two viable explanations:

   o Insuffient caching due to insufficient resources

   o Data is not being cached at all

Zfs reads whole 128K blocks (or whatever the filesystem blocksize is) 
at a time.  It does not read partial blocks from underlying storage. 
This makes it very expensive to perform many small read accesses if 
the reads are not subsequently cached in the ARC.

Bob
-- 
Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/