[rescue] Sun 711

[Chris Byrne]

Okay the goal here is to provide a full 300MB/s stream to storage. THis is
for video which means no interruptions and low latency.

It's reasonable to expect between 60 and 80% utilization on the best
equipment, so realistically you need four to six 100MB FC-AL adapters to
sustain 300MB of throughput.  You can do the same thing with 3-4 U160 HBA's.
You will also need raid controllers that have more cache than the single
largest dataset you will be trying to squeeze through them (I'd recommend
controllers with at least 512m cache if possible).You will also need enough
ram in the system to hold the largest dataset, the operating system, all
your utilities, and have a safety factor. Personally Id suggest at least a
gig, preferably more. And I would also recommend this be an SMP system, at
least two procs.

Then you need drives. The best drives out there today(not including solid
state) can't sustain much more than 30MB/s transfer rates. This is emprical
testing by thrid parties, not vendor technical info. Once again, 60%-80%
utilization is reasonable to assume so you'll need 14 drives. Three to four
drives will saturate an FC-AL channel, four to six a U160 channel so lets
say four drives per channel maximum, which is reasonable given the number of
controllers we need, so lets round up that drive number to 16 jsut to keep
things neat.

The theoretical limit for a 64/66 bus is about 500MB per second (8388608
bits in a MB, 4224000000 b/s on the bus = 503.54 MB/s), but you will be
lucky to see half that sustained. Empirical testing on Sun and Intel
suggests that 40% is a reasonable sustained utilization. RS/6000 gear seems
to do a bit better. Sridhar and I discussed it and he seems to think it's
lower interrupt latency.  I honestly don't know what it's like on SGI PCI
gear but I wouldnt assume it's any better. I don't know what the I/O
charachterisits of XIO gear are. Anyway what that means is that even with
64/66 busses you can only load two, MAYBE three HBA's per bus before you
start seeing contention.

Oh and none of this includes calculations for RAID overhead because it's
hihgly dependant on what RAID scheme and controllers you use

Okay so for our platform we need as a minimum

2 processors
1 gig ram
2 64 bit 66MHz busses
4 UI60 controllers
16 15K drives

In terms of sun machines the smallest box that's do this internally would be
an E450, though you could do it with an ultra 80 and external storage
chassis. I would recommend getting either four slot chassis, or a chassis
that allows for multiple channels at four drives per channel (this is the
maximum sun recommends per channel BTW). I dont know of any such chassis but
Im sure they exist.

Alternatively you could stream over multipath to an FC storage array. You
would need at least four to six FC controllers for this to account for
throughput losses due to the array and any possible switches etc... The same
bus and memory considerations would be there. I also don't know if any
current software/hardware combination will allow for six multipath channels
from the same host to the same LUN

You could also do something like dual HIPPI to a mainframe or something like
that, but Sridhar would know more about that than I would.

Chris Byrne



> -----Original Message-----
> From: rescue-admin at sunhelp.org [mailto:rescue-admin at sunhelp.org]On
> Behalf Of Gregory Leblanc
> Sent: 01 May 2002 23:38
> To: rescue at sunhelp.org
> Subject: Re: [rescue] Sun 711
>
>
> On Wed, 2002-05-01 at 15:17, Monty Walls wrote:
> > On Wed, 1 May 2002 17:06:54 -0500
> > "Shawn Wallbridge" <swallbridge at franticfilms.com> wrote:
> >
> > > Just wondering if the Sun 711 can take Ultra-160 SCSI drives
> and operate at
> > > U160 speeds.
> > >
> > > I need to figure out how to get 300MB/s (uncompressed 2K
> video) sustained on
> > > a machine. I am thinking two U160 PCI (64/66) RAID
> controllers with two
> > > 711's filled with 36GB 15k rpm Cheetah's.
> > >
> >
> > I'd opt for 2 PCI(64/66) Bus's first.
> > then 2 FC-AL adapters per bus (or U160s).  Need to allow for Murphy...
>
> I think you'd need 3 FC-AL adapters to get 300MB/sec.
>
> What sort of a machine are you going to put this in?  You shouldn't
> saturate a single 64/66 PCI bus, but there won't be a lot of space left
> over for, say, networking, or anything else.  Two PCI busses would be
> Better.  I think you'll want some pretty decent processors, and a
> boatload of ram if you're going to do this with software striping.  What
> platform are you thinking of using?  SPARC, SGI?  Not x86, we trust.
> :-)
> 	Greg
>
> --
> Portland, Oregon, USA.
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