Synology DS1621 Virtual Machine Manager s White Paper - Page 14

machines you can run and your ability to provision for temporary capacity spikes. Luckily, RAM memory is easily expandable with fully supported DDR3 and DDR4 memory modules for Synology NAS. Adding memory to computing nodes is highly recommended when planning for intensive VMM applications. Meanwhile, users can reduce RAM usage by employing lightweight operating systems and optimizing configurations. The following parameters contribute to RAM memory use: 1.5 GB 10% of RAM 250 MB 80 MB 2 GB 2 GB 1 GB 1 GB Virtual Machine Memory Use Memory reserved for Synology host - If host memory is 15 GB or smaller - If host memory exceeds 15 GB Virtual machine Virtual CPU Operating system - Windows 10 (64-bit) - Ubuntu 16.10 (64-bit) - CentOS 7.3 - Virtual DSM Memory approaching capacity When memory use on one virtual host appears to approach the limit, users running a VMM cluster with several hosts can perform live migration of VMs to a host with more available memory. However, it can pay to take a close look at the resource use reported by your guest operating system before concluding it is short on RAM. While a VM is running, all of the memory you assigned to it in VMM is permanently shown as in use in your DSM Resource Monitor. In reality, the guest operating system may not be using much of its memory quota. Linux operating systems tend to report that almost all their memory is in use. A closer look (for instance, using the "top" command) might show that most excess RAM is used as temporary cache. That means it is available for applications, or you could reassign RAM to other VMs. Upgrading system memory A full list of compatible RAM modules for Synology NAS can be found on our compatibility pages. Depending on the CPU platform of your Synology NAS, there might be different requirements for expanding system memory. This article provides general guidance, while more specific information can be found in your device's Hardware Installation Guide. 3. Appropriate Storage Setups Using Synology NAS for virtualization simplifies virtual storage configuration significantly. At the same time, advanced choices are available for those eyeing professional, large-scale 12 Configuration Guide