Recently I got a chance to install PVE 3.3 on quite a capable server (Dual 6-core Xeons, 128 RAM, SSD disks). Due to fact it has a lot of RAM I set up swap to only 8Gb thinking I'll newer need any (and I hate to spend SSDs for swap, too). I created and run some VMs, and as I finished I have 126 out of 128 GB assigned to machines. Guest OSes are Ubuntu server 12.04 and Windows 2008 R2. To my great surprise, after only two days of running I see that swap usage on hast server is 6 Gb, and I see no reason why it is so. The free -m command says this: Code: total used free shared buffers cached Mem: 128902 124397 4504 0 244 142 -/+ buffers/cache: 124010 4892 Swap: 8191 1334 6857 So I see 6.8 Gb of swap out of 8 is used now, quite a amount! I can play with swappiness variable, but should I do that or I'd better decrease RAM assignment on some of VMs to have some spare free RAM? Then how much RAM should I preserve and keep 'just in case'? I found no recommendation on that subject, but I think the question is serious: there are a lot of PVE servers nowdays uses SSDs (or something SSD-backed) as a storage, so wasting it as swap will wear it out and anyway decreases system speed. Thank you in advance for any help on this matter, PVE is great system and I hope this turns out to be easily resolvable question!