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Sudden surge of traffic and the server is slow
| Posted by Tomcatf14, 09-14-2010, 05:29 PM |
| One of the client's news portal has a surged of visitors due to a very interesting local news. The traffic doubled up overnight and the server was struggling to cope with it. The specs of the server is as below:-
Dual Xeon 5405
16GB DDR2 ECC RAM
2 x 320GB SATA 7200 (s/w RAID1)
I have tuned the webserver and mysql to allow more connections but the load was too high. The average load can go up as high as 40 during peak hours. The webserver can accept up to 352 concurrent connections now, up from 152 before the tuning. Memory usage should be still fine as only about 30MB swap being used as shown from "top" and "free".
The output from iostat is as below:-
Linux 2.6.26-2-amd64 (zz) 09/15/2010 _x86_64_
avg-cpu: %user %nice %system %iowait %steal %idle
23.95 0.00 4.44 0.80 0.00 70.82
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 28.06 1000.72 1154.44 1459026910 1683138720
sda1 28.05 992.46 1154.38 1446969730 1683053488
sda2 0.00 0.00 0.00 4 0
sda5 0.01 8.27 0.06 12056864 85232
sdb 30.07 1078.20 1154.44 1571984044 1683138720
sdb1 30.04 1069.93 1154.38 1559927008 1683053488
sdb2 0.00 0.00 0.00 4 0
sdb5 0.04 8.27 0.06 12056720 85232
md0 163.84 1221.37 1143.97 1780718146 1667876624
md1 0.01 0.01 0.05 16216 79440
Is this bad? or normal for a 3 years old server and hard disk? Is this a bottleneck from the CPU or HDD?
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| Posted by lynxus, 09-14-2010, 05:52 PM |
| 352 concurrent sessions still isnt much, Esp for a server of that power..
Not sure whats going wrong there...
Do you have a lot of sql querys running? Maybe try and run the DB in memory rather than flat file?
try a load test?
http://wiki.appnexus.com/display/doc...t+With+ab+Tool
Last edited by lynxus; 09-14-2010 at 05:56 PM.
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| Posted by Tomcatf14, 09-14-2010, 11:59 PM |
| Yes, the mysqld is taking up a lot of CPU resources...Can go up as high as 400-600% if i view from TOP.
How to run mysql in memory?
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| Posted by InstaCarma_Support, 09-15-2010, 12:49 AM |
| Check the MySQL instances running on the server using the command
mysqladmin processlist
Check if there are any unusual instances and also you will get to know which database connections are coming.
Also try making tweaks in my.cnf file.
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| Posted by lynxus, 09-15-2010, 04:54 AM |
| ALso backup your databases and run an optimize on your large tables.
Check your indexes are ok and that you have some decent indexes present.
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| Posted by 24nt7linux, 09-15-2010, 08:50 AM |
| Hi,
Run the command 'watch mysql proc stat'. You can see which database is using the resouces. If you found the database, then check whether the code is closing mysql connections after fetching the data.
Also, you can enable/increase query caching and buffering. This will have a considerable difference in the current server load.
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