Forum OpenACS Q&A: What kind of RAM to use?

I want to buy some RAM for our current PIII 650 "server". It is more a
regular computer. The mother board only supports a 100Mhz data rate, I
believe.

As I might want to get a Dell Power Edge 2450 soon, I thought to buy
133MHZ ECC-Registered SDRAM at www.crucial.com, and use it in my
current "server" as long as I don't have it. Is this going to work?

Is it a problem to combine for example a 128mb SDRAM 100Mhz and a
256mb SDRAM ECC-Registered 133Mhz?

Any concerns about crucial? Any other suggestions?

(I find Dell Ram shockingly expensive!!!)

Thanks

There's no problem mixing PC100 and PC133 RAM on a machine with a 100MHz FSB.  Just don't try running a 133MHz FSB machine with PC100.

If you mix ECC and non-ECC memory in the same box, the ECC feature won't be used on a LX/BX-based motherboard.  You have to have 100% ECC.

If your machine's based on a I810, I810E, I815E-based motherboard ECC isn't supported.  The memory will work but you'll not get ECC in other words.  Same if you got stuck with one of those I840 motherboards with the hub chip that lets you run with PC100.  You probably don't have on e of these I840+MCH kludges though 'cause Intel had to recall them since they were unstable.

If you aren't sure what you've got e-mail me the brand and model of your motherboard and I should be able to help you.

If you find Dell RAM shockingly expensive make certain you're not looking at one of their servers that requires RDRAM, which is still about twice as expensive as SDRAM (no matter who you buy it from) giving nothing near an equivalent boost in performance.

There's nothing wrong with using a "regular computer" as a server as long as you have quality parts.  The main advantage "real servers" like the PowerEdge get you are redundant hotswappable power supplies,  hotswap disks, etc.  If you don't mind your system being down while you replace broken parts a "regular computer" can be a much cheaper option.  It really boils down to how important it is to keep your site up as close to 365x24x7 as possible.

Dell (Adaptec?) has since released the source for the RAID
driver as a kernel module for the 2450 running Red Hat 6.2.

We have six of the 2450s and while they've been no trouble and
very reliable the fact is that the imbedded RAID hardware makes
upgrading the kernel a PITA.

could I contact you when problems occur with the kernel? I am not sure when I will get that server, so you can still relax...

Sure, although I last updated the kernels sometime late last year and don't remember the details. I believe Dell has a word doc (?) with the source that outlines the procedure for upgrading the kernel and if I remember right it was mostly correct. Maybe they have a better procedure now...I haven't checked in awhile.

BTW, the latest Dell catalog seems to indicate they have a new 2U rackmount called the 2500 or something that looks to replace the 2450. You might want to check those out before ordering.

Do you Mike or anybody else have experience with the 2550 that Mike suggested? I just found the Power App 120 with a "Linux Dual PIII CPU"! This must be marketing?!

Jerry Pournelle recommends a lot of things.

Pournelle's not *always* wrong, as this case proves.  But he's always a turkey :)

<blockquote> Depending on your opinion of Pournelle, his recommendation can be a
</blockquote>
warning to stay away.

Well, writing a column for Byte does NOT a computer expert make - I
would never suggest otherwise.  And I generally don't read his web
site at all for the computer-related content.  But for other topics,
his website is one of my all time favorites, DESPITE it's middling
disorganization, unattractiveness, etc.

But *if* Pournelle says he's tried other RAM brands over the years and
had failures, but never had failures with Crucial and Kingston, then
that seems like a useful, if entirely anecdotal, data point.