High hard disk usage when the server isn't even being used.

[djamu]

Hi

disk grinding at daily intervals:

updatedb -used by locate & slocate- indexes your system -except your pruned paths and FS's- everyday
> that is all files that changed, quite similar to ******* & osx file indexing

it's a default setting in debian ( and so also in ubuntu )
settings:

/etc/updatedb.conf

the cron job is in cron.daily > and so runs daily at a fixed time.

/etc/cron.daily/mlocate

regarding apache:

you most likely installed apache2 prefork

if it's serving dynamic pages ( php & the likes )
then each process ( depending on loaded apache modules ) is 15-32MB ( with me it's about 30MB on average )

if it's static pages then only a couple of MB are needed.


apache2 has a bad default setting ( big iron ) that spawns a couple of processes and keeps a couple in reserve.

following is important

the default MaxClients=150 setting.. when busy it will keep spawning processes until this maximum is reached ... in other words if your serving dynamic pages and have a busy server > worst case scenario is that apache will use 150x32MB = 4.8GB....

you can test this by refreshing a page it serves very fast ( tap the F5 key very fast for a minute )... your server will almost certainly die/ lock up in front you ....

a good reasonable setting for the couple of hundred pages your serving daily is

sudo vim /etc/apache2/apache2.conf

and look for following

<IfModule mpm_prefork_module>
    StartServers          5
    MinSpareServers       5
    MaxSpareServers      10
    MaxClients          150
    MaxRequestsPerChild   0
</IfModule>

a little lower you have the settings for the apache worker module .. just ignore those ( they're there for SMP machines with apache2 worker installed, full explanation of this is a little of topic )


I suggest changing previous into something like this... ( a save setting I use on low memory machines ).

<IfModule mpm_prefork_module>
    StartServers          2
    MinSpareServers       2
    MaxSpareServers      4
    MaxClients          6
    MaxRequestsPerChild   1000
</IfModule>

now apache will spawn maximum 6 processes > worst case 6*32MB= 192MB ... if you don't use MYSQL then 256MB ram will just do....

a little bit above that you have the KeepAliveTimeout parameter, change it to

KeepAliveTimeout 2

with

KeepAlive On

bye...

[linuxisevolution]

The maxclients thing on my server must be okay, because I went to my site and refreshed it 100 times at once, no hiccups at all lol. Thanks.

[djamu]

well I do suggest or rather urge you to match the maxclients to the available ram ... just in case some idiot runs a script fetching lots of pages / spawning lots of instances .... pretty easy to do
( most basic DOS attack you can imagine )....

just a good advice

[linuxisevolution]

well I do suggest or rather urge you to match the maxclients to the available ram ... just in case some idiot runs a script fetching lots of pages / spawning lots of instances .... pretty easy to do
( most basic DOS attack you can imagine )....

just a good advice

Well I think my largest page is 1mb, so spawning lots of pages wont do much... Besides, I watch my network constantly, so I will notice and block the ip.


BTW: DOS was awesome.