On Sun, Apr 4, 2010 at 8:55 PM, Brad <bene...@yahoo.com> wrote: > I had always thought that with mpxio, it load-balances IO request across > your storage ports but this article > http://christianbilien.wordpress.com/2007/03/23/storage-array-bottlenecks/has > got me thinking its not true. > > "The available bandwidth is 2 or 4Gb/s (200 or 400MB/s – FC frames are 10 > bytes long -) per port. As load balancing software (Powerpath, MPXIO, DMP, > etc.) are most of the times used both for redundancy and load balancing, > I/Os coming from a host can take advantage of an aggregated bandwidth of two > ports. However, reads can use only one path, but writes are duplicated, i.e. > a host write ends up as one write on each host port. " > > Is this true? > -- >
I have no idea what MPIO stack he's talking about, but I've never heard anything operating like he's talking about. Writes aren't "duplicated on each port". The path a read OR write goes down depends on the host-side mpio stack, and how you have it configured to load-balance. It could be simple round-robin, it could be based on queue depth, it could be most recently used, etc. etc. --Tim
_______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
