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"
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<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
2017-11-04 12:05 GMT-02:00 hw <hw@xxxxxxxx>:
>
> 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
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