scott.marlowe wrote:
Well, from what I've read elsewhere on the internet, it would seem the Opterons scale better to 4 CPUs than the basic Xeons do. Of course, the exception to this is SGI's altix, which uses their own chipset and runs the itanium with very good memory bandwidth.
This is basically what I read too. But I cannot spent money on a quad opteron just for testing purposes :)
But, do you really need more CPU horsepower?
Are you I/O or CPU or memory or memory bandwidth bound? If you're sitting at 99% idle, and iostat says your drives are only running at some small percentage of what you know they could, you might be memory or memory bandwidth limited. Adding two more CPUs will not help with that situation.
Right now we have a dual xeon 2.4, 3 GB Ram, Mylex extremeraid controller, running 2 Compaq BD018122C0, 1 Seagate ST318203LC and 1 Quantum ATLAS_V_18_SCA.
iostat show between 20 and 60 % user avg-cpu. And this is not even peak time.
I attached a "vmstat 10 120" output for perhaps 60-70% peak load.
If your I/O is saturated, then the answer may well be a better RAID array, with many more drives plugged into it. Do you have any spare drives you can toss on the machine to see if that helps? Sometimes going from 4 drives in a RAID 1+0 to 6 or 8 or more can give a big boost in performance.
Next drives I'll buy will certainly be 15k scsi drives.
In short, don't expect 4 CPUs to solve the problem if the problem isn't really the CPUs being maxed out.
Also, what type of load are you running? Mostly read, mostly written, few connections handling lots of data, lots of connections each handling a little data, lots of transactions, etc...
In peak times we can get up to 700-800 connections at the same time. There are quite some updates involved, without having exact numbers I'll think that we have about 70% selects and 30% updates/inserts.
If you are doing lots of writing, make SURE you have a controller that supports battery backed cache and is configured to write-back, not write-through.
Could you recommend a certain controller type? The only battery backed one that I found on the net is the newest model from icp-vortex.com.
Regards, Bjoern
~# vmstat 10 120 procs memory swap io system cpu r b w swpd free buff cache si so bi bo in cs us sy id 1 1 0 24180 10584 32468 2332208 0 1 0 2 1 2 2 0 0 0 2 0 24564 10480 27812 2313528 8 0 7506 574 1199 8674 30 7 63 2 1 0 24692 10060 23636 2259176 0 18 8099 298 2074 6328 25 7 68 2 0 0 24584 18576 21056 2299804 3 6 13208 305 1598 8700 23 6 71 1 21 1 24504 16588 20912 2309468 4 0 1442 1107 754 6874 42 13 45 6 1 0 24632 13148 19992 2319400 0 0 2627 499 1184 9633 37 6 58 5 1 0 24488 10912 19292 2330080 5 0 3404 150 1466 10206 32 6 61 4 1 0 24488 12180 18824 2342280 3 0 2934 40 1052 3866 19 3 78 0 0 0 24420 14776 19412 2347232 6 0 403 216 1123 4702 22 3 74 0 0 0 24548 14408 17380 2321780 4 0 522 715 965 6336 25 5 71 4 0 0 24676 12504 17756 2322988 0 0 564 830 883 7066 31 6 63 0 3 0 24676 14060 18232 2325224 0 0 483 388 1097 3401 21 3 76 0 2 1 24676 13044 18700 2322948 0 0 701 195 1078 5187 23 3 74 2 0 0 24676 21576 18752 2328168 0 0 467 177 1552 3574 18 3 78
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