CentOS and Cpanel

[RaZor Edge]

I have done some search on DEHE's forum about CentOS, and it seems that CentOS is not really recommended with Cpanel:

http://www.dehe.com/showthread.php?t...ghlight=centos
http://www.dehe.com/showthread.php?t...ghlight=centos

So, I would like to known if CentOS + Cpanel can cause major performance issue's?

(seems like when my VPS (444) was re-installed, for some reasons, Red Hat was switch for CentOS)

[Andre]

Hi,

That was when the CentOS 4 template was not released yet. However since we are running Virtuozzo 3 CentOS4 is supported and we use this by default on all VPS's except Plesk (since the Plesk templates for Virtuozzo don't support centos 4 yet).

Needless to say we have tested cPanel with CentOS 4 thoroughly. There is no performance difference of any kind, the only difference is that CentOS 4 uses much more up-to-date applications and libraries, which definitely makes CentOS the better choice.

[RaZor Edge]

Ok! Great. Thank you Andre!

[RaZor Edge]

Another question about CentOS.

When I was on Red Hat, with the TOP command, there was 1 httpd and 1 mysql process showed.

Now, there seems to have many of them:

 
top - 11:59:38 up 1 day, 11:02, 0 users, load average: 0.07, 0.29, 0.37
Tasks: 85 total, 1 running, 83 sleeping, 0 stopped, 1 zombie
Cpu(s): 5.2% us, 1.2% sy, 0.0% ni, 93.5% id, 0.2% wa, 0.0% hi, 0.0% si
Mem: 2039688k total, 152204k used, 1887484k free,		0k buffers
Swap:	57460k total,	26624k used,	30836k free,		0k cached
PID USER	 PR NI VIRT RES SHR S %CPU %MEM	TIME+ COMMAND																		 
15495 nobody	15 0 48236 10m 42m S 5.0 0.5 0:00.38 httpd																			
14132 nobody	16 0 48344 12m 42m S 4.0 0.6 0:02.28 httpd																			
5230 root	 15 0 1888 1012 1676 R 0.7 0.0 0:05.48 top																			 
14217 nobody	16 0 48444 11m 42m S 0.7 0.6 0:01.30 httpd																			
15541 nobody	15 0 48196 10m 42m S 0.7 0.5 0:00.30 httpd																			
15551 nobody	16 0 47676 9960 42m S 0.7 0.5 0:00.31 httpd																			
15553 nobody	16 0 47584 9972 42m S 0.7 0.5 0:00.17 httpd																			
15559 nobody	16 0	 0	0	0 Z 0.7 0.0 0:00.02 httpd <defunct>																 
7535 mysql	 16 0 118m 57m 5360 S 0.3 2.9 0:01.74 mysqld																		 
13422 nobody	16 0 48320 12m 42m S 0.3 0.6 0:04.44 httpd																			
14321 nobody	15 0 48192 11m 42m S 0.3 0.6 0:01.23 httpd																			
15443 nobody	16 0 47472 9.9m 42m S 0.3 0.5 0:00.44 httpd																			
	1 root	 16 0 1620 596 1420 S 0.0 0.0 0:00.11 init																			 
18116 root	 16 0 1520 588 1356 S 0.0 0.0 0:00.47 syslogd																		 
21516 root	 16 0 3988 1640 3616 S 0.0 0.1 0:00.03 sshd																			 
21741 root	 15 0 43108 5336 40m S 0.0 0.3 0:25.97 httpd																			
21749 root	 16 0 2464 792 1532 S 0.0 0.0 0:04.88 crond																			
22197 named	 18 0 39288 2812 4840 S 0.0 0.1 0:00.00 named																			
24344 root	 35 19 13500 10m 4604 S 0.0 0.5 0:12.19 cpanellogd																	 
24388 root	 18 0 4032 1188 3688 S 0.0 0.1 0:00.00 saslauthd																		
24414 root	 18 0 1476 504 1312 S 0.0 0.0 0:00.00 portsentry																	 
20187 root	 16 0 2144 1108 1952 S 0.0 0.1 0:00.00 mysqld_safe																	 
20213 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:02.98 mysqld																		 
20214 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:00.01 mysqld																		 
20215 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:05.12 mysqld																		 
20221 mysql	 16 0 118m 57m 5360 S 0.0 2.9 0:13.96 mysqld																		 
20412 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:12.75 mysqld																		 
20413 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:18.25 mysqld																		 
22002 mysql	 16 0 118m 57m 5360 S 0.0 2.9 0:12.86 mysqld																		 
22003 mysql	 16 0 118m 57m 5360 S 0.0 2.9 0:16.55 mysqld																		 
22004 mysql	 16 0 118m 57m 5360 S 0.0 2.9 0:12.85 mysqld																		 
22005 mysql	 16 0 118m 57m 5360 S 0.0 2.9 0:14.68 mysqld																		 
5906 mysql	 15 0 118m 57m 5360 S 0.0 2.9 0:15.48 mysqld 
 
(and there is more mysql process like this...)

Is this a normal behavior? (There is only 1 website on my VPS)

[Andre]

Yes that is normal. Each mysql (or httpd) process can only handle a certain amount of queries. If there are more queries than 1 process can handle, the daemon will simply start another process in order to dealw ith the queries.

If your VPS has a lot of mysql usage I would recommend to turn on query caching. The same goes for httpd usage; in that case look into using eaccelerator (which is also a caching application).

[Andre]

Oh and also: note that on RedHat 9 the multiple processes thing was also happening, but it was only showing 1 process in top. That's probably due to that it's a different top version.

[RaZor Edge]

Yes that is normal. Each mysql (or httpd) process can only handle a certain amount of queries. If there are more queries than 1 process can handle, the daemon will simply start another process in order to dealw ith the queries.

When the server is less busy, are these additionnal process suppose to shut down themself, or they will stay there waiting to be use again?

Oh and also: note that on RedHat 9 the multiple processes thing was also happening, but it was only showing 1 process in top. That's probably due to that it's a different top version.

Ok!

[Andre]

When the server is less busy, are these additionnal process suppose to shut down themself, or they will stay there waiting to be use again?

They'll stop themselves.

[helmishariff]

From what I know, dehe will upgrade to new version of virtuozzo within 2, 3 weeks. So, do you change the OS from RH9 to CentOS4? You have mentioned the performance will gain from this upgrading. Please update this upgrade project so I can do some benchmark.

[Andre]

Customers who are now on RedHat9 would keep RedHat9. The only way to change to CentOS4 is a reinstallation.

Note that the change from RH9 to CentOS4 does not get you better performance. Only the change from Virtuozzo 2 to Virtuozzo 3 will get you much better performance, but it doesn't matter which OS template you use.

If you want to check whether your VPS has been migrated to Virtuozzo 3 yet enter this command in SSH:

uname -a

If the output starts with 2.4 you're still on Virtuozzo 2 and will be upgraded shortly. If the output starts with 2.6 you have already been migrated to Virtuozzo 3.

[helmishariff]

mine, not yet. still on kernel 2.4.