[Linux-cluster] GFS or Web Server Performance issues?

[gordan at bobich.net]

I think a part of the problem is perception. Clustering in most cases 
leads to _LOWER_ performance on I/O bound processes. If it's CPU bound, 
then sure, it'll help. But on I/O it'll likely do you harm. It's more 
about redundancy and graceful degradation than performance. There's no way 
of getting away from the fact that a cluster has to do more work than a 
single node, just because it has to keep itself in sync.

The only way clustering will give you scaleable performance benefit is 
with partitioned (as opposed to shared) data. Shared data clustering is 
about convenience and redundancy, not about performance.

Gordan

On Tue, 27 Nov 2007, isplist at logicore.net wrote:

>> Using a load balancer in front of GFS nodes is tricky. Make sure to set
>> your scheduling rule (or whatever it is called in LVS) in such a way
>
> Do you mean such as a session, so that the user is not moved between servers?
> That's something I did take into account when building the LVS LB's. I also
> have tested with the LVS and direct to the web nodes. The performance is just
> not what I expected but mind you, I've not done any fine tuning yet.
>
> Are there a series of steps I should be taking? I see a lot on the net but
> it's not too clear which things I really should try doing first.
>
> Mike
>
>
>
>> that it would not generate un-necessary lock traffic. For example, you
>> don't want the same write lock to get rotated between three nodes. Be
>> aware that moving a write lock between nodes requires many steps that
>> include a disk flush.
>>
>> -- Wendy
>>
>>> These are pretty much default apache RPM versions out of the box.
>>>
>>> # ab -kc 50 -t 30 http://192.168.1.150/
>>> This is ApacheBench, Version 2.0.41-dev <$Revision: 1.141 $> apache-2.0
>>> Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd,
>>> http://www.zeustech.net/
>>> Copyright (c) 1998-2002 The Apache Software Foundation,
>>> http://www.apache.org/
>>>
>>> Benchmarking 192.168.1.150 (be patient)
>>> Finished 130 requests
>>>
>>>
>>> Server Software:        Apache
>>> Server Hostname:        192.168.1.150
>>> Server Port:            80
>>>
>>> Document Path:          /
>>> Document Length:        8997 bytes
>>>
>>> Concurrency Level:      50
>>> Time taken for tests:   30.234185 seconds
>>> Complete requests:      130
>>> Failed requests:        0
>>> Write errors:           0
>>> Keep-Alive requests:    0
>>> Total transferred:      1371090 bytes
>>> HTML transferred:       1299586 bytes
>>> Requests per second:    4.30 [#/sec] (mean)
>>> Time per request:       11628.532 [ms] (mean)
>>> Time per request:       232.571 [ms] (mean, across all concurrent
>>> requests)
>>> Transfer rate:          44.25 [Kbytes/sec] received
>>>
>>> Connection Times (ms)
>>> min  mean[+/-sd] median   max
>>> Connect:        0    1   1.4      2       4
>>> Processing:   409 6228 4357.5   5227   16317
>>> Waiting:      369 6146 4370.8   5199   16261
>>> Total:        409 6230 4358.1   5230   16321
>>>
>>> Percentage of the requests served within a certain time (ms)
>>> 50%   5230
>>> 66%   8331
>>> 75%   9310
>>> 80%  10386
>>> 90%  12820
>>> 95%  14502
>>> 98%  15399
>>> 99%  15746
>>> 100%  16321 (longest request)
>>>
>>>
>>> --
>>> Linux-cluster mailing list
>>> Linux-cluster at redhat.com
>>> https://www.redhat.com/mailman/listinfo/linux-cluster
>
>
>
>
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