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I have ESXi running on an old cast off desktop machine. It's running a quad core AMD Phenomn 9850 Black edition cpu, 4 gig of DDR2 ram, and an SSD for the data store. The guest operating systems are LAMP servers hosting about a dozen sites. For the most part it runs just fine, until a site decides to run a backup or beat up on its database. Then everything, on every guest VM, starts crawling. Looking at the ESX performance charts the CPU is the bottle neck. When it hits about 50% utilization everything slows down.

So, its upgrade time. I've budgeted $400 - $500 for the CPU and I'm faced with a choice. Which gives me more performance for running files compressions, database look-ups/changes, and web hosting a single more expensive 6 core Xeon or two less expensive quad core Xeons? (looking at Newegg 6 core Xeons start at around $500, give or take)

A second related question, can you run a single processor on a 2 processor mother board.

(finally a clarification. This is a server that will be mounted in a rack. It will be asked to run 24x7x365 without a glitch or hiccup while serving up web pages, accessing databases used by those sites and running compression on the backups. It will never, ever, never be a gaming machine, used to render videos, heck it won't even have a monitor attached.)

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closed as not constructive by ewwhite, mdpc, SvW, thinice, Zoredache Dec 13 '12 at 18:17

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Strange that you would ask us to compare two CPUs without telling us which two CPUs they are. –  David Schwartz Dec 13 '12 at 17:54
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Are you certain your problem is related to the CPU and not I/O? Last time I looked Mysql backups were not really all that CPU intensive. –  Zoredache Dec 13 '12 at 17:56
    
I don't get it, why has this question been closed as not constructive? It is about professional level equipment that will be ordered in the next few days. The question rephrased is "are two less expensive processors better than one more expensive processor?" –  jsigned Dec 13 '12 at 20:08
    
In response to David the question is "are two quad core processors better than one 6 core all other things being equal?" So, processor Ghz, ram speed, IO, etc, etc, etc the same. I've never done, or for that matter seen written up, an answer to my question. –  jsigned Dec 13 '12 at 20:15
    
Zoredache - The issue isn't MySQL backups, those are done in a flash, but to save offsite storage space I compress the backups. The sites vary in size, but the biggest is about 10 gig that gzip's down to about 5 gig. Before the ssd drive was installed it took over 2 hours to zip to a spinning drive. With the ssd the backup takes 12 minutes, during which the CPU is pegged and none of the sites are as responsive as they should be. When a user is making a lot of updates to their database the CPU will bump momentarily to 50% and for that moment, everyone else gets to wait. –  jsigned Dec 13 '12 at 20:25
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2 Answers 2

A second related question, can you run a single processor on a 2 processor mother board.

This one is easy to answer: Yes you can.

Which gives me more performance for running files compressions, database look-ups/changes, and web hosting a single more expensive 6 core Xeon or two less expensive quad core Xeons?

This one is harder.

A two CPU system with two 4 cores would:

  • Effectively have 8 cores.
  • Have more memory bandwidth
  • Require a more expensive dual socket motherboard
  • Will need multiple populated memory banks

And ofc that is assuming similar CPUs (e.g. no older generation 6 core vs a newer generation 4 core or vice versa)

This would make the dual socket motherboard the better and likely more expensive answer.

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I would go with two processors as, in my experience, two processors offers the ability to utilize all the RAM slots on the motherboard, where a single CPU may not afford you that luxury.

To answer your second question, yes you can run a single processor on a dual processor mobo.

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