Optimize the server for Magento 2

In my magento shop we can not order and show server error [login to view URL] We want finish this job within 2 days, this server is install Litespeed enterprise we server We have upgrade to VPS server for Magento 2 (6 x 2.50GHz Cores, 16 GB ECC RAM). Our support tell me following information: Firstly, I checked to see if all the necessary requirements for Magento were actually running on your server. I noticed that Elasticsearch had actually been stopped because your server had run out of memory: Nov 7 21:25:09 node7079 kernel: Out of memory: Killed process 1059696 (java) total-vm:6224756kB, anon-rss:2481004kB, file-rss:0kB, shmem-rss:0kB, UID:987 pgtables:5760kB oom_score_adj:0 I have reviewed the server and I was able to find only a few reports for low memory (RAM). Nov 7 21:25:09 node7079 kernel: Out of memory: Killed process 1059696 (java) total-vm:6224756kB, anon-rss:2481004kB, file-rss:0kB, shmem-rss:0kB, UID:987 pgtables:5760kB oom_score_adj:0 Nov 8 06:20:08 node7079 kernel: Out of memory: Killed process 1621283 (java) total-vm:6224664kB, anon-rss:2439572kB, file-rss:0kB, shmem-rss:0kB, UID:987 pgtables:5472kB oom_score_adj:0 Nov 8 06:48:11 node7079 kernel: Out of memory: Killed process 1631285 (java) total-vm:6224912kB, anon-rss:2421824kB, file-rss:0kB, shmem-rss:0kB, UID:987 pgtables:5412kB oom_score_adj:0 Once the memory is low the server kernel starts killing services in order to reduce the memory usage. In this case, the Java service was terminated. The Java service is used by Elasticsearch so the consumption is coming from Elasticsearch and the operations executed to it. The Elasticsearch service is highly memory-dependent and has a minimum requirement of 8GB of RAM. The recommended requirement is 16 GB and you can check this in its official documentation here. > [login to view URL] Your server currently has 8GB of RAM capacity. Having this in mind the website that will be using Elasticsearch should be very well optimized in order to avoid memory issues. I advise you to review your websites and optimize them for less resource consumption. You can also consider and address the matter with a professional developer who will be able to assist with the optimization since the matter requires development knowledge.