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Re: 515 not performing to full rating due to disk arms?



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From: Scott Lindstrom <SLindstrom@xxxxxxxxxx>
To: midrange-l@xxxxxxxxxxxx
Date: Thu, 12 Jun 2008 10:54:09 -0500
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<FONT face=3D"Default Sans Serif,Verdana,Arial,Helvetica,sans-serif" size=
=3D2><DIV><FONT face=3D"Default Monospace,Courier New,Courier,monospace">Ph=
illip - this is great info!&nbsp; Do you have a link of the name/number of =
the redpaper you refer to so I can take a look at it?</FONT></DIV><DIV><FON=
T face=3D"Default Monospace,Courier New,Courier,monospace"></FONT>&nbsp;</D=
IV><DIV><FONT face=3D"Default Monospace,Courier New,Courier,monospace">Is i=
t this one?:</FONT></DIV><DIV>IBM System i Overview: Models 515, 525, 550, =
570, 595, and More</DIV><DIV><FONT face=3D"Default Monospace,Courier New,Co=
urier,monospace"></FONT>&nbsp;</DIV><DIV><FONT face=3D"Default Monospace,Co=
urier New,Courier,monospace">from: Philipp Rusch - NewVision-IT &lt;philipp=
.rusch@xxxxxxxxxxxxxxx&gt;<BR>subject: <BR>Scott Lindstrom schrieb:<BR>&gt;=
&gt; Since you can only have 8 drives on a 515, the only constraint would<B=
R>&gt;&gt; have be memory.<BR>&gt;&gt; What are "they" recommending for a b=
ox ?<BR>&gt;&gt; What does this application do and what is the primary lang=
uage ?<BR>&gt;&gt; &nbsp; &nbsp; <BR>&gt;<BR>&gt; Pat-<BR>&gt;<BR>&gt; The =
box is being quoted at 3gb of memory. The app is JD Edwards World<BR>&gt; (=
English).<BR>&gt;<BR>&gt; If 3gb is not enough RAM to get the rated CPW, I =
wonder what is?<BR>&gt;<BR>&gt; The BP recommends an M25 series box.<BR>&gt=
;<BR>&gt; Scott<BR>&gt;<BR>&gt; &nbsp; <BR>Hello Scott,<BR><BR>CPW Measures=
are ALWAYS meant for the system being fully equipped with<BR>every disk, m=
emory and cache controller you can put in.<BR>BUT: The i5-515 is a special =
one, as is the 510-M15. These machines are<BR>politically constrained, whic=
h means that you cannot use the full CPU-Power<BR>if you are running I/O in=
tensive jobs on them. The good news is, that <BR>there is<BR>no more "Hyper=
visor job" artificially contorlling how much power you can <BR>get.<BR>Ther=
e is a note in the Redpaper about these new systems an I think your BP<BR>i=
s referring to that:<BR>Note 1: The Model 515 provides full processor power=
(batch or 5250 OLTP) <BR>for applications that are not I/O intensive. For =
applications<BR>that are I/O intensive, this translates to approximately 80=
0 CPW (batch <BR>or 5250 OLTP) for either the 1-way or 2-way because the Mo=
del<BR>515 has a maximum of eight disk drives. CPW is used to compare relat=
ive <BR>performance rating among processor models within the IBM<BR>System =
i family.<BR>As a reminder, do not use CPW as the sole metric for sizing wo=
rkloads on <BR>any IBM System i model. Additional considerations include<BR=
disk I/O-per-second rates and application workload attributes. As a <BR>st=
arting point for disk I/Os per second on the Model 515, consider a<BR>maxim=
um of approximately 115 disk I/Os per second. We recommend that you <BR>siz=
e a Model 515 workload using a sizing tool, such as<BR>the IBM Systems Work=
load Estimator, which you can access at the <BR>following address:<BR></FON=
T><A href=3D"http://www.ibm.com/servers/eserver/iseries/perfmgmt/sizing.htm=
l" target=3D=5Fblank><FONT face=3D"Default Monospace,Courier New,Courier,mo=
nospace">http://www.ibm.com/servers/eserver/iseries/perfmgmt/sizing.html</F=
ONT></A><BR><BR><FONT face=3D"Default Monospace,Courier New,Courier,monospa=
ce">That said, it depends on what you do with your i5. It certainly runs Ja=
va or<BR>a WAS-instance a lot more faster than a model 800 with 800 CPW wou=
ld do.<BR>But don't expect it to run 5 times as fast with a "traditional" w=
orkload.<BR>Some numbers for comparison:<BR>The 515 maxes out at 16 GB memo=
ry with 533 MHz, 8x 70 GB 15k SCSI disks<BR>and two RAID controllers, one w=
ith 40MB and the other one with a 90 MB <BR>cache.<BR>The 520-M15/25 maxes =
out at 16 GB memory with 667MHz, 6x 70 GB 15k SAS disks<BR>(well it's not t=
hat easy: the load source shall be 70 GB, the other <BR>disks can be up<BR>=
to 283 GB per diskdrive, but then how to build a RAID5 ...)<BR>The SAS disk=
are a little faster than the SCSI ones, but you only got 6 <BR>arms in<BR>=
an M15. The M25 is allowed to be expanded beyond this with an EXP24 disk<BR=
addition for instance ...<BR><BR>So the question is: how many user-license=
s do you need ?<BR>The 515 ends at 40 users, if you exceed this, you need a=
n M25, otherwise it<BR>makes no difference for me.</FONT><BR><BR></DIV><DIV=
<BR>&nbsp;</DIV></FONT>=





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