before I switched to Ubuntu 16.04 64bit server on my VSPes (based on OpenVZ), I used to read the output from free and htop to analyze the actual RAM usage. Now with 16.04 that comes with the new free and htop things has changed and I can't no longer understand how to read it. I thought it was because of the OS version but it also happens on 14.04 with those packages updated. From that link seems like -available- in free is the equivalent of the old +/- cached/buffered but this output was 4MB in +/- cached/buffered under "free", now it's:

root@server3:~# free
              total        used        free      shared  buff/cache   available
Mem:         131072       85884           0       73460       45188        3566
Swap:             0   

what does that even compared to the old one? On old free I had almost 120MB left to use if necessary by other processes (and it was true from what I tested), here it's completely different.

Also on htop I see more ram used than the amount available... uh? It used to be 4/128MB there as well.

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Could these bugs of OpenVZ maybe?

  • 1
    It would be probably better seen with 'free -m' to see the capacity in MB. Yes, the available is the ammount of memory, which is available to new applications, before swapping strikes. – Jaroslav Kucera Oct 2 '17 at 19:42
  • Things is on 14.04 with OpevVZ I always had 90% of the RAM free now on 16.04 it's almost always the opposite. And even it shows 0 as available its increase when needed without killing apps or swapping (I don't have any swap). That is very confusing. Either the memory management completely changed or the RAM reporting is f**ked by openvz with new versions of Ubuntu. – Sandro Antonucci Oct 11 '17 at 20:34

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