[CentOS] mariadb server memory usage

Disk cache is not recommended for databases servers.

 it'll  slow down the performance. More ram equals more performance.

This link help me understand memory usage on linux.

https://www.linuxatemyram.com/

Basically you need yo worry about

free memory is close to 0
used memory is close to total
available memory (or "free + buffers/cache") has enough room (let's say,
20%+ of total)
swap used does not change
Warning signs of a genuine low memory situation that you may want to look
into:

available memory (or "free + buffers/cache") is close to zero
swap used increases or fluctuates
dmesg | grep oom-killer shows the OutOfMemory-killer at work


You can monitory swap with "vmsat 1"

<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>
Livre
de vírus. www.avast.com
<https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail>.
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

2017-11-04 12:05 GMT-02:00 hw <hw at gc-24.de>:

>
> Hi,
>
> is this ok for a database server, or do I need to turn the memory allowance
> down?  The machine has 48GB and mariadb is allowed about 40. The
> machine is a dedicated database server.
>
> Mysql seems to go up to what top says is virtually allocated under some
> circumstances; I don´t know what mariadb does.  I don´t want anything
> get killed because memory runs out.  Swap should prevent that anyway,
> but perhaps I went a bit higher than I should?
>
> Usual advice is to use 80%, and there are probably reasons for that.
> Perhaps it´s better to allow for more disk cache?
>
>
> KiB Mem : 49449424 total,   291772 free, 45891836 used,  3265816 buff/cache
> KiB Swap: 16777212 total, 16742928 free,    34284 used.  2985816 avail Mem
>
>   PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
>  4138 mysql     20   0 48.908g 0.042t  14064 S   0.0 91.8 111:23.17 mysqld
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
>