Is it worth installing Synology Virtual Machine VMM? I put a Windows machine in the DS920+, and I've counted all the memory and pitfalls for you

before the 2016 laptop at home officially retired, I came up with a lazy idea: move all its work to the Synology NAS, download the device, run the script, and occasionally check out some old software remotely. The DS920+ sits right next to the weak current box, with the quad-core CPU usually occupying less than 10% of the time, so it's idle when it's idle. So I installed a Virtual Machine Manager, called a virtual machine manager in Chinese, abbreviated as VMM below. After more than a month of turmoil, I managed to write down all the accounts and pitfalls.

the threshold, check yourself: half of Synology can't fit

check the model before you start—this step can turn half people away. VMM only supports the Plus series, which refers to x86 machines with a plus sign, such as the DS920+, DS923+, DS1522+, DS1621+, as well as the more expensive XS series. My other DS220j is completely out of the loop—the J series uses ARM architecture, and you can't find VMMs in the kit center, so don't bother bothering.

the official statement for memory is that over 2GB can run a virtual machine, which is true, but only half true. In actual tests, a Windows 10 machine allocates 4GB of memory, but it only barely allows it to open; it works when booted, and after opening two browser tabs, it starts spinning in circles. If you really want to use comfortably, you have to upgrade the machine to 8GB first. My machine only dared to run freely after adding 16GB of RAM later. I wrote an article about the upgrade process NAS a memory upgrade test, a DS920+ machine costs 50 yuan to do it yourself.

another point that's easiest to overlook: virtual machine disks can only be built on the Btrfs storage pool. My first trip was a failure here. Back then, when I set up the storage space diagram, I conveniently chose ext4, but when creating a virtual machine in the VMM, the storage location column was grayed out and I couldn't select it. Features like snapshots and cloning rely entirely on Btrfs's write-time replication, which ext4 cannot provide. If you're struggling with which file system to choose, you can check out my previous ext4 comparison with Btrfs. If you want to play with virtual machines, the conclusion of that article is to just switch to mindless Btrfs. If you've already chosen ext4, don't rush to reinstall—backup and rebuild are costly. Think carefully about whether you really want to play with a virtual machine.

Windows Installation Record: Three Hours Stuck on Drivers

VMM main unit can be installed for free in the Suite Center. After installation, the interface will display the three large characters "Virtual Machine," click New, select Windows 10, and allocate 2 cores, 4GB RAM, and 60GB virtual disk. Network bridging is by default. The next step went smoothly. After installing the system, I checked the issue: the network card in Device Manager had a yellow exclamation mark and couldn't connect to the internet; Disk transfer speeds are only about 20MB/s, as slow as if you've returned to the era of mechanical drives.

answer is VirtIO drives. The VMM virtual machine uses a semi-virtualized device by default. It has good performance but Windows doesn't recognize it, so you need to manually install the driver package provided by Synology: First, upload the VirtIO ISO to the NAS, shut down the virtual machine, edit it, and point a CD drive to this ISO. After booting, enter Device Manager and manually update the drivers for those unknown devices. After installing the network card, it was immediately recognized, and the disk was running at the speed an SSD should have. I spent three hours in total, two of which were spent questioning my life. Try to put SSD storage pools on the virtual machine's disks; putting them on a mechanical drive takes over a minute to boot. Don't ask me how I know.

also has a Guest Agent, a widget installed in Windows. After installing the VMM panel, you can see the actual memory usage inside the virtual machine. When taking snapshots, the file system is frozen first to ensure consistency. Don't save on that, it's a matter of a minute.

daily use without connecting a monitor, enter the NAS address into the browser to enter the VMM page, open the virtual machine, and a window will appear directly to see the Windows desktop, experiencing the same as remote software. I also have a DS file client on my phone, which can be connected to the emergency and clicked twice with the mouse. If you really want to work long-term, the computer version is more comfortable. I used this Windows as a downloader for half a month, running tasks for two hours on schedule every day, then shutting down automatically on time. It's more worry-free than a laptop and has a better power consumption account.

Windows installation is the minority; soft routers are the mainstream approach

after a month, I found that Windows installations at Synology are actually a minority. In the community, VMM installations are mostly soft routing systems, like iKuai and OpenWrt. The logic is simple: one machine simultaneously acts as both a NAS and a router, all in one. Even small machines with 4GB of RAM can be saved. You can install a 32-bit AiKuai as a bypass router, only handling offloading and occupying less than 1GB.

network is the most winding part of the soft router gameplay. In the VMM, each virtual machine's network card is attached to a virtual switch, which then bridges to a physical network port. As the main router, you have to bridge the WAN port and LAN port to two different physical network ports: the optical modem enters one port, the switch outputs the other. After installation, you have to go to the control panel to correct Synology's own network configuration. If you make a mistake, the whole family will be disconnected, including the NAS itself—then you'll have to use the monitor and keyboard to connect directly to save it. VMM supports network card passthrough very limitedly; most models can only use bridge, which is usable but uses a bit more CPU than true passthrough, so don't expect 10GB intranets.

My advice is to start with a side router for the first time: single network card, bridge, and connect the main router to the main router. If you mess up, just unplug the virtual machine network card and keep the whole home network running normally. Once you get really involved, consider the main routing plan and write down the rollback route first and stick it in the weak current box.

snapshots are truly tempting: take a shot before the fuss

VMM the feature I can't live without is the snapshot. Taking a snapshot of a virtual machine means freezing and saving the entire current system state. No matter what you do inside—installing unknown software, changing the registry, upgrading the system and crashing—it takes just a few seconds to restore it to the moment it was taken. This month, I took seven snapshots of Windows virtual machines—two to save lives, and one time when some old software installed a system that caused a blue screen and restored the snapshot in five minutes to resolve the battle.

snapshots consume a lot of storage space, and taking more shots can take up a significant amount. Before shooting, it's best to install a Guest Agent on the virtual machine to ensure snapshot consistency. This snapshot is the same underlying mechanism as the Btrfs file system snapshot. In my previous article on ransomware protection , the gate on shared folders was the same: read-only archives can't be found by bad stuff.

the cost of the matter will be settled before deciding

have talked about so many benefits, but the cost must be laid out. I have stepped on the order in which I have tried:

there's another hidden cost: every bit of CPU lost to the virtual machine is competing with Docker and the photo album index. If you're just installing a virtual machine to run a downloader or use qBittorrent, check out my article Docker beginner's . If a container can solve the problem, don't open a virtual machine. The former consumes about 100MB of memory, while the latter starts at 2GB. The truly irreplaceable scenarios for virtual machines are: must run the full operating system, install Windows-exclusive software, or run a soft router system.

Taking Positions: Who Should Play, Who Should Avoid It

give a concrete conclusion. Use: The machine is a Plus series with 16GB of RAM, clearly requires Windows software or soft routers, has an SSD Btrfs storage pool, and a UPS is installed. Bypass: The machine is J-series or ARM architecture, 4GB of RAM, still running album indexes and containers, just heard it's fun and want to try it out—those really want to try it out. PVE or Feiniu is another story, but I'll include the system selection in Synology vs. Feiniu comparison article.

Here's the

order: first check the model and memory, then confirm the storage pool is Btrfs, allocate a space for the virtual machine's SSD, install the VirtIO driver and Guest Agent first, take snapshots before any high-risk operation, and finally install the UPS. After completing these six steps, VMM becomes an honest tool for getting things done; Skip steps to play, and it can show you a blue startup screen at any time.