[owncloud-user] Which is the best server configuration for ownCloud?

Marcos Mezo mmezo at selexco.net
Thu Feb 27 12:44:20 MET 2014

Hello list,

> On 02/26/2014 12:37 AM, Pierre Malard wrote:
>> localu at nuage:~# free -h
>>              total       used     free     shared    buffers     cached
>> Mem:          4,0G       3,7G     279M         0B       395M       1,8G
>> -/+ buffers/cache:       1,5G     2,5G
>> Swap:         1,0G       7,1M     1,0G
>> but, elsewere, if 5 users needs 1,5 Gb RAM, what about needed RAM for 50?
> it doesn't mean that all of that RAM is used for Apache. There are 
> countless tools to measure RAM usage, but for a quick look, e.g. this 
> script can be helpful (it just presents some values from proc): 
> https://raw.github.com/pixelb/ps_mem/master/ps_mem.py
> Run it once with apache running and once without, and compare it to 
> the output of free (column used - cached).
As a summary for the article linked in a previous post 
and maybe some other readings I've done over time:

Linux thinks: "memory not used = memory wasted". So it will use all the 
memory you give at it. If you happen to increase the assigned memory to 
your owncloud VM, you'll probably see it fill too, even with the same 
software and number of users as now. If i've undestood correctly, if the 
kernel has nothing better to do, it uses memory as a filesystem cache 
and uses as much as he can (to some limit). If/when later some 
application needs the memory it either discards the buffered files to 
free some pages or maybe even swaps them off to disk.

Even seeing some swap used is per se not critical. The problem is when 
the system is actively/continously swapping or maybe swaping in critical 
moments for example when doing a backup or similar. To see if you are 
memory bound and thus using swap actively and therefore having 
performance problems, you can use the vmstat util (in debian it comes on 
the sysstat package).

For example in my laptop right now:

root at portatilmmg:~# free -h
              total       used       free     shared    buffers cached
Mem:          3,6G       3,2G       408M         0B 196M       1,2G
-/+ buffers/cache:       1,8G       1,7G
Swap:         2,0G       720M       1,3G

you see I have 720Mb of swap, but I really don't care because using 
vmstat I can see that swap is not really beeing used:

root at portatilmmg:~# vmstat 5
procs -----------memory---------- ---swap-- -----io---- -system-- 
  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy 
id wa
  0  0 737268 409640 201236 1218112    1    1    59    13    5 4  6  2 91  0
  0  0 737268 410332 201264 1214852    0    0     0   310  587 1131  2  
2 95  1
  0  0 737268 414712 201264 1210612    0    0     0     4  450 884  2  1 
97  0

vmstat 5 prints the stats every 5 seconds. Under the header swap, si and 
so mean swap in and out, the bytes entering or going out of the swap. 
You can see that they are always 0. So swap is not beeing used at all. 
There is something stored there for "future" reference, but that's it.

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