On Wed, Jan 16, 2008 at 10:45:34AM -0500, Miguel Gonzalez Castaños wrote:
> 
> Pasi Kärkkäinen escribió:
> > On Wed, Jan 09, 2008 at 11:13:26AM -0500, Miguel Gonzalez Castaños wrote:
> >   
> >>     
> >>> Well, this is your problem. Fix it first.
> >>>
> >>> If you can't get better throughput with FTP/HTTP/CIFS, how could you with
> >>> iSCSI? 
> >>>
> >>> Sounds like you're running at 100 Mbit/sec.
> >>>   
> >>>       
> >> I'm researching on this matter. I have tested from the machine where 
> >> Virtual Server is running using hrping:
> >>
> >> hrping -l 4096 -t 10.0.6.41
> >>
> >> Statistics for 10.0.6.41:
> >> [Aborting...]
> >>     Packets: sent=70, rcvd=70, error=0, lost=0 (0% loss) in 34.500313 sec
> >>     RTTs of replies in ms: min/avg/max: 0.304 / 0.331 / 0.426
> >>
> >> from your calculations that means around 13 MB/s
> >>
> >> Even at my home LAN where I have a very cheap gigabit switch and I use 
> >> CAT 5e (so I'd meant to get around 200 Mb/s) and I'm getting with hrping 
> >> around 15 MB/s
> >>
> >> Maybe We have something wrong with our switches (my boss says that all 
> >> are gigabit) or with our cabling.
> >>
> >> Thanks!
> >>
> >>     
> >
> > OK.
> >
> > Remember that 4k I mentioned was just an example, because that's the often
> > used block size by many filesystems.. 
> >
> > If you do (or if your application does) larger requests, you can easily get
> > much more throughput.. for example 128k requests will give you much more
> > throughput..
> >
> > And then you can have many outstanding io's active at the same time..
> > depending on the used queue depth, io elevator etc..
> >
> > iometer (on windows) let's you choose number of outstanding io's..
> >
> > But yeah, first fix the throughput to be good with FTP/HTTP/CIFS and then
> > start playing with iSCSI.
> >   
> I've connected a cross-over cable and created an ad-hoc network. hrping 
> is not being very meaningful:
> 
> hrping -L 4096 -t 10.0.7.41
> 
> RTTs of replies in ms: min/avg/max: 0.228 / 0.266 / 1.121
> 
> However, I have installed bing. The performance it gives is around 500 
> Mbps in the cross-over network.
> 

500 Mbps sounds OK, but not very good.. you should get more. Have you done
any tcp/ip stack option tweaking? There is a lot of network memory/socket 
options to tune for gigabit links/transfers.. (at least in Linux).

Also some network driver settings/parameters affect the performance. 

> The problem here is both machines are running Windows, the open-iscsi 
> client would be running in a Virtual Server machine running Debian.
> 

Ouch. I have never measured performance of Linux VM under MS Virtual
server.. so no idea about that. 

> Running bing from the host Virtual Server against the debian virtual 
> machine reduces the performance to around 60 Mbps. The tulip driver in 
> Debian for Virtual Server configures a Fast Ethernet network card. 
> Although Microsoft claims that the real performance is limited by the 
> physical network, apparently is not the case for Debian virtual machines.
> 

Well, here you go.. if you only get 60 Mbit/sec between the host and the
Linux VM, that's the problem..

Can you change the emulated NIC to something else from the Linux VM? 
Does MS have optimized (=paravirtualized) NIC drivers available for 
use in the Linux VM? 

Have you tried VMware Server or ESX? 

> About the MTU, I get 1500 in the client part, in the initiator. Do I 
> need a bigger MTU? Is it possible to change that?
> 

I don't know what MS Virtual Server supports.. you might get better
performance with jumbo frames (9000 bytes), but not necessarily.. it depends
a lot of the switches used etc. 

Good ethernet flow control implementation is more important for iSCSI than 
jumbo frames. If you need choose between flow control and jumbo frames,
choose flow control.. (some switches can't do both at the same time - and
many switches have bad flow control implementation - so be careful).

-- Pasi

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