Re: FreeBSD iscsi target

On Wed, Jul 02, 2014 at 03:26:09PM +0400, Slawa Olhovchenkov wrote:
> On Tue, Jul 01, 2014 at 10:43:08PM -0700, Kevin Oberman wrote:
> 
> > On Tue, Jul 1, 2014 at 4:13 PM, Slawa Olhovchenkov <slw_at_zxy.spb.ru> wrote:
> > 
> > > On Tue, Jul 01, 2014 at 11:12:52AM +0200, Edward Tomasz Napierala wrote:
> > >
> > > > Hi.  I've replied in private, but just for the record:
> > > >
> > > > On 0627T0927, Sreenivasa Honnur wrote:
> > > > > Does freebsd iscsi target supports:
> > > > > 1. ACL (access control lists)
> > > >
> > > > In 10-STABLE there is a way to control access based on initiator
> > > > name and IP address.
> > > >
> > > > > 2. iSNS
> > > >
> > > > No; it's one of the iSCSI features that seem to only be used
> > > > for marketing purposes :-)
> > > >
> > > > > 3. Multiple connections per session
> > > >
> > > > No; see above.
> > >
> > > I think this is help for 40G links.
> > >
> > 
> > I assume that you are looking at transfer of large amounts of data over 40G
> > links. Assuming that tis is the case, yes, multiple connections per session
> 
> Yes, this case. As I know, single transfer over 40G link limited by
> 10G.

This is not correct.  A 40Gb link does not limit a single transfer to
10G.  For example, on FreeBSD all common bandwidth benchmarks reach
40GbE line rate with a single TCP connection at mtu 1500.  If a single
transfer were limited to 10G you'd need 4 connections to get there.

The physical signalling is over four lanes so it's easy to split a 40G
link into four separate 10G links.  But when running as a 40GbE (this is
the usual case) the hardware will combine all the lanes into a single
40G data stream, and you get to use all of the bandwidth.

Regards,
Navdeep