Re: Large (8M) cache vs. dual-core CPUs

As others have noted, the current price/performance "sweet spot" for DB servers is 2S 2C AMD CPUs. These CPUs are also the highest performing x86 compatible solution for pg.

If you must go Intel for some reason, then wait until the new NGMA CPU's (Conroe, Merom, Woodcrest) come out and see how they bench on DB workloads. Preliminary benches on these chips look good, but I would not recommend making a purchase decision based on just preliminary benches of unreleased products.

If you must buy soon, then the decision is clear cut from anything except possinly a political/religious standpoint.
The NetBurst based Pentium and Xeon solutions are simply not worth the money spent or the PITA they will put you through compared to the AMD dual cores. The new Intel NGMA CPUs may be different, but all the pertinent evidence is not yet available.

My personal favorite pg platform at this time is one based on a 2 socket, dual core ready mainboard with 16 DIMM slots combined with dual core AMD Kx's.

Less money than the "comparable" Intel solution and _far_ more performance.

...and even if you do buy Intel, =DON"T= buy Dell unless you like causing trouble for yourself.
Bad experiences with Dell in general and their poor PERC RAID controllers in specific are all over this and other DB forums.

Ron

-----Original Message-----
>From: Bill Moran <wmoran(at)collaborativefusion(dot)com>
>Sent: Apr 25, 2006 2:14 PM
>To: pgsql-performance(at)postgresql(dot)org
>Subject: [PERFORM] Large (8M) cache vs. dual-core CPUs
>
>
>I've been given the task of making some hardware recommendations for
>the next round of server purchases. The machines to be purchased
>will be running FreeBSD & PostgreSQL.
>
>Where I'm stuck is in deciding whether we want to go with dual-core
>pentiums with 2M cache, or with HT pentiums with 8M cache.
>
>Both of these are expensive bits of hardware, and I'm trying to
>gather as much evidence as possible before making a recommendation.
>The FreeBSD community seems pretty divided over which is likely to
>be better, and I have been unable to discover a method for estimating
>how much of the 2M cache on our existing systems is being used.
>
>Does anyone in the PostgreSQL community have any experience with
>large caches or dual-core pentiums that could make any recommendations?
>Our current Dell 2850 systems are CPU bound - i.e. they have enough
>RAM, and fast enough disks that the CPUs seem to be the limiting
>factor. As a result, this decision on what kind of CPUs to get in
>the next round of servers is pretty important.
>
>Any advice is much appreciated.
>

>My personal favorite pg platform at this time is one based on a 2 socket, dual core ready mainboard with 16 DIMM slots combined with dual core AMD Kx's.
>
>
Right. We've been buying Tyan bare-bones boxes like this.
It's better to go with bare-bones than building boxes from bare metal
because the cooling issues are addressed correctly.

Note that if you need a large number of machines, then Intel
Core Duo may give the best overall price/performance because
they're cheaper to run and cool.

Ron Peacetree wrote:
> As others have noted, the current price/performance "sweet spot" for DB servers is 2S 2C AMD CPUs. These CPUs are also the highest performing x86 compatible solution for pg.
>
> If you must go Intel for some reason, then wait until the new NGMA CPU's (Conroe, Merom, Woodcrest) come out and see how they bench on DB workloads. Preliminary benches on these chips look good, but I would not recommend making a purchase decision based on just preliminary benches of unreleased products.
>
> If you must buy soon, then the decision is clear cut from anything except possinly a political/religious standpoint.
> The NetBurst based Pentium and Xeon solutions are simply not worth the money spent or the PITA they will put you through compared to the AMD dual cores. The new Intel NGMA CPUs may be different, but all the pertinent evidence is not yet available.
>
> My personal favorite pg platform at this time is one based on a 2 socket, dual core ready mainboard with 16 DIMM slots combined with dual core AMD Kx's.
>
> Less money than the "comparable" Intel solution and _far_ more performance.
>
> ...and even if you do buy Intel, =DON"T= buy Dell unless you like causing trouble for yourself.
> Bad experiences with Dell in general and their poor PERC RAID controllers in specific are all over this and other DB forums.
>
> Ron
>

To add to this... the HP DL 385 is a pretty nice dual core capable
opteron box. Just don't buy the extra ram from HP (they like to charge
entirely too much).

Joshua D. Drake

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On Apr 25, 2006, at 5:09 PM, Ron Peacetree wrote:

> ...and even if you do buy Intel, =DON"T= buy Dell unless you like
> causing trouble for yourself.
> Bad experiences with Dell in general and their poor PERC RAID
> controllers in specific are all over this and other DB forums.

I don't think that their current controllers suck like their older
ones did. That's what you'll read about in the archives -- the old
stuff. Eg, the 1850's embedded RAID controller really flies, but it
only works with the internal disks. I can't comment on the external
array controller for the 1850, but I cannot imagine it being any slower.

And personally, I've not experienced any major problems aside from
two bad PE1550's 4 years ago. And I have currently about 15 Dell
servers running 24x7x365 doing various tasks, including postgres.

However, my *big* databases always go on dual opteron boxes. my
current favorite is the SunFire X4100 with an external RAID.