Synology DS918+ quick notes

Just bought a new NAS for home, and decided on a Synology DS918+ with 4 10TB drives ($539 + 4 x $310). Why not another ReadyNAS? A combination of price and vague dissatisfaction with the ones I’ve used in the past; I may write that up sometime.

Why not FreeNAS? Because I didn’t feel like building one from scratch right now (as much as I like the idea of a ZFS-based NAS), and the prebuilt unit we once bought from iXsystems ended up going back due to being a piece of junk. Both Synology and ReadyNAS use BTRFS as their filesystem format these days, which offers a lot of what you get with ZFS without the need to occasionally resort to command-line incantations. (“Not That There’s Anything Wrong With That!”)

Drive installation was painless (simple snap-in hot-swap trays), and while I found the “desktop” web GUI a bit overdone, everything works well. The biggest annoyance was figuring out which of the “private cloud” packages to add, because they recently changed all that, resulting in some confusion. (short version: only install the Drive package and desktop/mobile clients, and open TCP ports 5000, 5001, and 6690; also use the builtin LetsEncrypt support and set everything to require SSL)

The “EZ-Internet” cloud/firewall config was useless; it’s just a UPnP wrapper, and when it realized that it couldn’t auto-configure my OpenBSD router, the only help it offered was “hey, you should open some ports”, with no indication of which ones were actually required for the installed packages (see above).

Side note: I was amused and pleased that Drive, their latest, greatest personal cloud solution, required installing the Perl package. 😜

I went with their ‘hybrid’ RAID config, SHR-1, because it resizes better when you add more drives or swap in larger drives. This gives me 26 TB in usable space (9.1 * 3 - overhead), which is plenty for now. Down the road, if when media, disk images, and automated backups start to fill that up, I’ll add the DX517 expansion chassis and another 5 10TB drives and bring it up to 52 TB usable.

If you’re following along at home, you may wonder why adding 5 drives doesn’t give closer to 70 TB, and the answer is paranoia. SHR-1 uses a single parity drive, which means you can only afford to lose one disk. This is generally not a huge problem if you have a spare on-hand and swap it in immediately, but there’s a non-trivial risk that another drive will fail while the first one is rebuilding.

If you think about it, this is even more likely when you buy all your RAID disks at once from the same manufacturing batch, so you really want two parity disks and a hot spare, so that the system can start rebuilding as soon as one disk fails, and can survive losing another one during the rebuild. Having only one data disk in a four-disk chassis isn’t terribly useful, so for now I’m running in a cheaper, less-paranoid configuration. When I’m sure that I like the Synology enough to really rely on it, I’ll buy the expansion and convert the RAID to SHR-2 with a hot spare. And buy a cold spare disk as well.

Additional performance enhancements I can add include bonding the two 1-gigabit ports together, bumping the memory (official max 8GB, but there are reports that 16GB works), and adding SSD cache drives. That last is specifically why I chose the 918+, since it has a pair of M.2 slots on the bottom, and some of their other models require you to buy an expansion card first.

Building the volume was quick, but it took ~16.25 hours to run the initial parity consistency check, so performance was sub-optimal until that finished. The GUI was occasionally a bit sluggish during that time.

Next up: setting up dedicated Time Machine volumes for the Macs and testing their Windows backup client.

Oh, and I named it Index.


First Time Machine backup complete. Just because I was curious how well it would work, I backed up 425 GB over wireless, which took about 7.5 hours.

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