Memory and disk useage

[MikeLoeritz]

Hi

After a great reply to my last query I thought I would post another!

We have installed Plesk 11 for Linux on a dedicated server (OVH) as their standard Ubunto and Plesk install. All works great. We are only hosting 5 domains for EMAIL ONLY but I am a little concerned.

The min requirements say that 500mb or RAM is required or 1GB for many accounts.

This server has 4GB and shows in plesk server info as

Total 3.84GB
Used 3.80GB
Free 41.78MB
Shared 0
Buffer 193MB
Cached 2.53GB
Usage 32.9%

I may be thick (well, I am) but why is only 41MB available... is the server about to explode? But if only this is available why does the overall show only 32% Use? Will we be ok?

Also, Disk space....

Although the bulk of our stuff (emails etc) are clearly being stored in the bottom section shown below (and we have 420 GB free out of 500GB) the root section seems to increase in useage also the more the emails get used. I did some tests and added an inbox with 3GB of emails and it increased the useage in the 2nd partition by 3GB so thats where things are being stored but the root went up a bit too.. I worry as this section is so small that it will fill. Is this normal for it to use root area for anything other than the install?

/dev/root
19 556.81 MB
1 986.46 MB
16 554.41 MB
10.16%

Protected directories /opt/psa
/dev/md2
449 134.04 MB
6 646.92 MB
419 649.93 MB
1.48%
Protected directories /var/lib/mysql
/var/www/vhosts
/var/qmail/mailnames
/var/named/run-root


Thanks for the help!
A concerned
Mike

 

[abdi]

Mike,

The Linux kernel will use available memory for disk caching, unless it's required by a running program.

This is considered good; say you have 4 GB RAM, and your programs are using only 1 GB. The other 3 GB are going to waste. Despite the "feel-good" impression from knowing you're only using 25% of your memory, the counterpart is that the other 75% is going unused. So the kernel uses that for caching files which significantly improves performance. It's automatic; unlike older operating systems you don't need to decide how much to devote to disk cache, or manually configure it.

"The Linux disk cache is very unobtrusive. It uses spare memory to greatly increase disk access speeds, and without taking any memory away from applications. A fully used store of ram on Linux is efficient hardware use, not a warning sign."

This is such a common question that there's an entire website devoted to it:

http://www.linuxatemyram.com

The website even has a way to empty the disk cache so you can then run some applications and see how much faster they are with the cache enabled

 

[MikeLoeritz]

Thanks for the reply Abdi,

So, it sounds like on RAM we are pretty safe running for what we need on 4GB?

As for the root section of the hard drive being used more, I presume this is related and that the actual storage will not go to the root section but the other partition? I just saw the root section go from 9 to 11% used and thought "crikey" because we have only sent a few emails and obviously using IMAP and keeping things on the server I was worried!

I see you offer support as per your footer... this could come in very useful with some things we want to do... how do I send you a PM on this forum? lol

 

[abdi]

I see you offer support as per your footer... this could come in very useful with some things we want to do... how do I send you a PM on this forum? lol

Yes we do, you just order a level 3 ticket here:

http://www.jolis.net/packages.php?spt=47