[H-GEN] Upgrading a Sun E250

James C. McPherson James.McPherson at Sun.COM
Fri Jan 17 07:52:46 EST 2003


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Hi Michael,
answers/comments inline below

On Fri, 17 Jan 2003 21:08:38 +1000 "Michael Anthon" <michael at anthon.net> wrote:
> My main server at work is in dire need of some extra disk space.  It's a Sun
> E250 and is currently fitted with 4x9G drives that mostly contain the OS and
> Oracle installation and another 2x32G drives, one of which contains the data
> and the other being used as a holding area for backups.
> http://sunsolve.sun.com/handbook_pub/Systems/E250/spec.html is a spec for
> the machine.
> I have noted that the built in SCSI is only a 40MB/sec system.  Obviously a
> faster SCSI bus would be a rather nice benefit to me since the poor old
> machine is I/O bound a large percentage of the time when it is trying to do
> stuff.  

what are you doing to this machine? how have you measured the performance
in order to determine that the disks are your problem? What is the actual
config of the machine in terms of cpus(speed?), memory, disk layout (are
you using disksuite or vxvm? raiding?) Since you're running oracle, what 
is the oracle version and config? are you doing re-indexing via temp spaces
on disk or in memory? And what do you mean by "holding area for backups" ??

> So my question is kinda multi pronged.
> 1.  Is it possible to install another SCSI card that can then be used to
> drive the internal drive bays, and if so, what implications does this have
> for the existing drives?  I can foresee a couple of issues here.  Will the
> backplane design of the drive bays be suitable for the higher bus speeds?
> Will the existing drives be compatible with this higher speed?

Answers: no. possibly. yes

> 2.  What's the deal with mixing different UltraSCSI speeds?  In my research
> it seems that the newer and faster drives are backward compatible with the
> slower busses however I can't determine if the slower drives are compatible
> with a faster bus.  Will the SCSI card simply just throttle back the bus
> speed to the lowest common denominator or is it just no going to work?

if the scsi card doesn't detect any handshaking/negotiation problems with the
older/slower devices, then the controller should not have a problem with 
having different speed devices on the bus. 

> I just don't have the knowledge required to answer these questions and I
> can't really find definitive answers anywhere.  The whole topic of SCSI
> compatibility is terribly confused, not in small part due to the number of
> people out there who think they know what they are talking about when that
> really don't and end up mixing their terms..  Any definitive answers would
> be greatly appreciated.

I don't think you've got the right end of the problem to start with. 

Firstly, define the problem.
Secondly, determine how you are going to measure your system's vital
statistics in order to prove or disprove your problem statement.
Thirdly, _if_ (2) turns out to prove (1), then investigate each specific
area of performance degradation and work out how to improve that area 
by itself. 
Fourthly, join the set of solutions for (3) and see what you get.

You might want to take this offline -- I'm happy to give you some assistance
if you want it.

best regards,
James C. McPherson
--
Pacrim PTS Engineer            828 Pacific Highway
                               Gordon NSW 
Sun Microsystems Australia     2072











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