more RAM + faster disk -> slower box?!

Paul Richards paul at freebsd-services.com
Thu Nov 29 18:22:17 GMT 2001


--On Thursday, November 29, 2001 16:06:40 +0000 Ian Pallfreeman
<ip at mcc.ac.uk> wrote:

>> Go for it, but if taking out memory fixes the problem, then there will
>> be a  public ceremony for Manchester BSDers in the Lass O' Gowrie where
>> I will eat  my BSD horns and tail, date and time to be announced. :-)
> 
> You're a gentleman, a man of your word, and you're going to get
> indigestion.
> 
> Apparently (thanks Sam) I need "registered DIMMs" (whatever they are) in
> order for the board to cache more than 512MB. Our so-called engineers
> knew nothing about this; I got the usual shrugs from them when I asked
> about it. I mean,  I know I always get poor quality hardware, I just
> didn't expect it to be  quite this bad...

That makes no sense at all. Registered DIMMs have a register in them to
help with bus loading i.e. you can stick a lot more RAM into a box that
uses registered memory, it has no bearing on cacheability at all.

Did I miss Sam's email somewhere?
 
> So, taking the memory down to 512MB has fixed the problem. My load
> averages  are down to 1-2 again, innd is spending almost all of its time
> in biord or  inode wait, and the nnrpds are waiting on the network not
> burning CPU. I'm  considering removing the remaining 512MB in hope that
> this will improve the  performance even more...
> 
> Thanks to everybody who answered my call for help. Ain't PC hardware shit?
> But at least we've got software we can trust, hm?

Umm, maybe not if removing memory has improved the situation.

Paul Richards
FreeBSD Services Ltd
http://www.freebsd-services.com




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