marcos valentine wrote: >> This free memory can go away in less than a second > > It's depends of many things. But you need to pay attention on this variables > > https://mariadb.com/kb/en/library/mariadb-memory-allocation/ Thanks, that´s an interesting page. It tells you to turn off hyperthreading. At some other place on the mariadb website, I´ve been reading it´s generally a good idea to leave it turned on for mariadb. Now which is true? > In my db servers i use nagios to monitor when "free" and "available" ram is > less than 80% warning state and less than 5% critical. Hmm, nagios, yes, I should look into that. >> so I figured why not use as much as possible --- just not too much, and > this is borderline. > > You can use the rule always 80% used for safe. But 20% of 46GB could be too > much ram wasted. It would be a pity to waste it. I think 128GB would be ideal, and the machine might even get that once I get to shuffle the RAM sticks around between different machines. I still wouldn´t want to waste any.