"You can never have too much RAM ..........."

..... or so i thought until i was reading a post "What are your server's
specs?" and "SuperGumby" replied :

~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"How many SBS's do you have with more than 2GB RAM? Have you hit the
problems many people seem to when having more than 2GB RAM? Is there some
secret thing you do which allows these servers to operate nicely while having
more than 2GB RAM?"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

So i've just ordered a server :

PROLIANT ML370 XE-3.0G/533 2X36GB (15K) SCSI 2X512MB G3 x 1
ML370/DL380 G3 XDP3060 DUAL PROCESSOR UPGRADE KIT x1
18.2GB PLUG ULTRA320 15K SCSI 2
36.4GB PLUG ULTRA320 15K SCSI 1
SMART ARRAY 641 PCI-X CONTROLLER 1
2GB 266MHZ DDR PC2100 SDRAM 2

Which will give me 4GB PC2100......... this HP stuff is seriously expensive
- have i made a major mistake?

 

I'm not aware of any problems with more than 2 GB ram - what have I missed ?

I will say that I've not noticed much benefit from ram over 2 GB.

 

If you are running the Premium version and using MSSQL for a database
application the extra ram helps. Our version of MSSQL uses 1 gig itself.

Tony

 

Hi Tony,

Yeah, I run SQL as well. It's very unscientific I know, but I just didn't
perceive any difference going from 2 gb to 3. I'm sure it depends on the
workload.

Anyway, even though I see no benefit in my case, like I said, I see no
problem either.

--
Les Connor [SBS Community Member]
-------------------------------------
SBS Rocks !

 

before this gets outta hand.

OK, one question neeeds changing.
Have you hit the problems SOME people seem to when having more than 2GB RAM?

There's been a couple of threads started on performance issues. The posters
either were already or were advised to use /3GB and va switches but this did
not address the issue. In at least two cases removing RAM down to 2GB seems
to have resolved it.

We have a few reasonably high use SBS's out there, we're not pushing user
count limits but loaded by either intensive use or the addition of third
party software on the SBS. In recent times we are advising the installation
of 2GB RAM but many are still at 1. There are no indications that
performance of these systems would be limited by RAM.

I'm genuinely interested in the responses to the questions, and maybe a
couple of others.

Do you run SBS on more than 2GB?
Are you prepared to perform an experiment for me? Please reduce the RAM to
2GB and monitor system performance, does either gut feel or statistical data
indicate a performance drop? (I sortta don't really expect anyone to take me
up on this. Unfortunately, due to Performance Tuning this may have a long
term effect on the system and may be impacted by the time the server has
been running the larger amount of RAM)

There's a point of diminishing return. Also, in general I have found that if
more RAM is required very little benefit is gained by going from X to 1.5X,
the next logical step from 2GB is 4GB. Is the cost of the additional RAM
justified?

 

I hear you SuperGrumpy, and actually I mostly agree.

There is a noticeable performance increase, even on a lightly loaded SBS,
when you go from 1 to 2 GB. Not so with 2 to 3. I won't bother again (or
until the need for real metrics comes around).

I've used and not used the /3gb switch for servers with 1 GB or more of ram.
There was some confusion early on, but I believe that the consensus is now
firmly *do not use the switch on sbs, regardless of how much ram is in the
box*. (keeping in mind, I don't have any SBS with more than 3 GB, most are 1
or 2.) I really don't know if that would change if you had 4 GB.

So I have *no* servers with the /3gb switch anymore. But I'll say I never
recognized a problem either way.

Susan has a link to a discussion on the /3gb switch, more than anyone ever
wanted to know about it. (as in, sorry I brought the subject up).

--
Les Connor [SBS Community Member]
-------------------------------------
SBS Rocks !

 

I think part of the problem with the /3gb switch is that most people don't
understand what it does

Raymond Chen had a recent series on his blog about /3gb which is quite
informative:
http://weblogs.asp.net/oldnewthing/archive/2004/08/22/218527.aspx

Cheers
Ken

 

proof I'm not only reading it but also stuff referenced by it.

I never knew this.

'''''''''''''''
Btw, one of the tidbits that came out of my discussion with the MM guys was
the maximum paging file size on a system:

· On a regular x86 machine, you can have 16 paging files, each is 4G
in size, for a total of 64G.

· On an x86 running in PAE mode, you can have 16 paging files, but
each can be 16tb in size, for a total of 256tb of paging file space.

'''''''''''''''''
http://weblogs.asp.net/larryosterman/archive/2004/05/05/126532.aspx


--
Mick Malloy
http://www.micropol.com.au

 

OK, I read just about everything, and have now had time to both get over the
headache and digest the flood.

If you don't want my interpretation please feel free to carry on with your
life and 'mark as read'.

SBS is a busy box. The SBS dev team have done a number of things to enable a
single box to satisfy several criteria MS recommends against.
Exchange/ISA/SQL on the same box, SHEER LUNACY. AND you want this thing to
not only be first (and possibly only) DC in your AD but also the primary
fileserver. We've always known we were special.

If you implement the /3GB switch you take resources away from the system to
be allocated to programs. This is probably not a good idea.

Though there are references which recommend NOT implementing this on SBS
there are many ways for someone investigating a problem to arrive at the
other conclusion.'YEP, got Exchange, got heaps of RAM, I'll not only do the
/3GB bit but also that userva stuff'. We CAN'T ask MS to post a red 37pt
headline on every related KB "BTW, SBS admins shouldn't do this' but I think
I may have a solution.

Would it be possible for a Service Pack or HotFix to inspect boot.ini on SBS
systems and alert you that 'The /3GB switch is enabled in your boot.ini,
we're not going to fix it for you but recommend this be removed" ?

BTW, I've tried the /3GB and the userva, never fixed anything so I've
removed them.
BTW2, call me masochistic but I actually enjoyed reading most of the linked
stuff.
BTW3, I reckon on small SBS's they may actually have benefit. (Please don't
rush off and do it unnecessarily)

 

Hi again SG,

I have been following this thread pretty closely, and also just got done
reading some of the BLOGs about the /3GB switch and what it *really* does.
Back in Nov of 2003, I started a thread referring to Exchange throwing some
exceptions. Susan was kind enough to point me to eventID, and these
exceptions were cleared up with a reboot - obviously not fixing the problem
but making it go away for the time being.
I then got a reply from Rick Morris [MSFT] saying that with 1GB RAM, I would
be better served by putting in both the /3GB and /USERVA switches. At the
time, I did not have any other references regarding the /3GB switch, so I
did as suggested in my boot.ini.
Since then I have not had the issue crop up again.
So, now I am wondering: Has there been a shift in Microsoft policy and/or a
change made with one of the SP/hot fixes to exchange that would make these
switches erroneous?
After reading the Blogs, I understand what the /3GB does, and I am not
convinced that it did not help in my case...
{my head hurts}...
Reference to the previous thread in Nov of 2003:
http://groups.google.com/groups?hl=...=%2F3gb+jerry+dubuke&hl=en&btnG=Google+Search

Jerry

 

AWWW HECK, if I have a headache from doing it you can suffer buddy.

I'm not sure all MS contributors are familiar with SBS.

SHEEEIT, I just can't live with that statement. I'm pretty sure some of the
MS guys who drop in haven't got a clue about SBS, but then many of the nonMS
contributors also don't have a clue about SBS. And to tell you the truth
there's a LOT of nuts and bolts which I may express an opinion over which I
do from gut feel as much as anything else.

and umm, someone once suggested I was wrrrrrrrrrr, incorrrrrrrr,
mistaaaaaaaaa. Something like that. Maybe a couple of times.

Maybe the dev team know what should apply to a bog standard install. Maybe
their knowledge doesn't apply to a system which also has other apps on it.
Maybe if the world didn't have so many ifs buts and maybes we'd all live
easier lives.

I seem to remember the recommendation NOT to apply the /3GB and va switches
being around before I had a problem which led me to believe I should. I
think there was argument in the group at the time.

I think I'd have to side with the MS guys at the moment (no switches) but
consider it worth trying if my applications were manipulating large data
sets.

is this a copout?
Rick suggests 'Use performance monitor to trace virtual bytes used by the
STORE.EXE process to track actual memory being
used by the store.exe process per the KB's instructions...Task Manager is
not good enough.' and this may be applicable to all applications. If you
have a runaway application you may do well to break the rule of thumb.

 

OK - so the end result is "YMMV" - gotta love it...
I am leaving them in, since I have had no detrimental effacts to date (just
about a year) with them in place.
This server is running Std, so no SQL/ISA. Not sure if that makes a
difference, but I believe it proabaly would change the rules a bit. I also
have almost no 3rd party apps (other than Symantec A/V and Mail security for
SMTP).
{shrugs shoulders} who knows?
Thanks for the pointers to the blogs - good reading overall!
Jerry

 

Just for the record...

I'm running 3GB of RAM on SBS2003 Premium with the /3GB switch and the
userva in the boot.ini file. I did it during setup and have never removed
it so I don't know if it is helping or neutral. In any case, it is not
hurting the system.

....FWIW
-Trevor

 

The /3gb switch changes the balance for VM from 2Gb for Applications
and 2Gb for the OS to 3Gb for applications and 1Gb for the OS.

Exchange "want" the /3gb switch because they manage to consume 2gb of
VM. My view on this would be that if Exchange can eat its' way through
2Gb, what's to stop it chewing up 3gb?

I think it's fundamentally a flaw in Exchange's memory management, and
that they ought to be finding out why/how and putting a stop to it.

And it doesn't seem to have been mentioned yet, but SBS2003 has a limit
on the RAM it can use of 4Gb. So there's absolutely no point *anyone*
trying to put more than 4Gb in an SBS machine.

 

You're confusing real RAM and virtual memory vs address space .

You can have multiple applications, each of which get allocated a 3GB
address space running on a PC with less than this amount of memory. Matter
of fact, how many applications and processes are currently running on your
PC? EACH and EVERY ONE has been allocated a 2GB address space for it's own
use.

 

No, I don't think so - I was making two separate points.

True, but that is not affected by the 4Gb physical RAM limit (which is
imposed by the SBS OS).