And that difference can be a huge deal if you want a ton of extra storage space or just more volumes or RAID configurations. In this case, the cost difference between the two is lower than getting an expansion unit.

Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermal sensitive systemseries: RS4021xs+, RS3621xs+, RS3621RPxs, RS2821RP+, RS2421RP+, RS2421+, RS1221RP+, RS1221+, DS1821+, DS1621xs+, DS1621+ Considering you can find hard drives of 20TB and higher capacities nowadays, the number of drive bays is not that important. So, if one can live with fewer bays, the DS1821+ has nothing to justify the more expensive cost compared to the DS1621+. Upgrade Synology systems with faster networking speeds. Thorough validation ensures seamless integration with DSM.

the number of connections that can be maintained when the recommended number of hosted files was reached) What's more, each server has two built-in M.2 slots to host two NVMe SSDs -- a good upgrade option if you use the server for applications that can benefit from caching. There's no way to use these slots for general storage. Both the DS1821+ and DS1621+ are excellent servers. They are essentially the same, except the former has two more built-in drive bays. And that worked with all the upgrades, too. In my case, I tried the migration with all the parts mentioned above installed on the DS1621+ then moved them, together with the hard drives, to the DS1821+.By the way, you should only cache a hard drive volume. If you use SATA SSDs for storage, caching is unnecessary. On top of that, if you decide to cache, it's also a better idea to upgrade the server's network to 10Gbps -- more below -- or at least use its Link Aggregation feature to get a 2Gbps connection out of its two Gigabit ports.

The second option is the least expensive but is good enough for most cases. Synology DS1821+ vs DS1621+: Here are my servers upgraded to 10Gbps using two different dual PCIe cards. The DS1621 Digital Thermometer and Thermostat provides 9–bit temperature readings which indicate the temperature of the device. The thermal alarm output, TOUT, is active when the temperature of the device exceeds a user–defined temperature TH. The output remains active until the temperature drops below user defined temperature TL, allowing for any hysteresis necessary. Generally, Bill, there’s no need to worry about the fans’ noise in Synology servers. They are quiet and you can control their speeds, too. What you might want to consider is the noise of the hard drives. And that varies. But it’s never good to put a NAS in your bedroom. Reply The 5-bay DX517 expansion unit uses an eSATA connection, which caps at 5Gbps, to connect to the server. Dallas Semiconductor was an American company that was founded in 1984 and was a supplier of mixed-signal and digital semiconductors.

A compact SMB NAS with great performance and a lot of flexibility

User-defined temperature settings are stored in nonvolatile memory so parts may be programmed prior to insertion in a system. Temperature settings and temperature readings are all communicated to/from the DS1621 over a simple 2-wire serial interface.

In any case, installing the SSDs onto the server is super easy. The two M.2 slots are inside the server's left wall. Take the first and second drive bays out, and you can reach them. Synology DS1821+: 10Gbps NIC card upgrade If you use a Comcast gateway, I think only Comcast can fix the issue. And I think they’ll fix it for free. Thanks for an awesome writeup. I have a server for Plex Media Server (and various other things) that uses 4x USB3.1 16TB drives in 2x RAID-1 (one cold spare, not mounted other than during sync) on a Linux server. User-defined temperature settings are stored in nonvolatile memory so parts may be programmed prior to insertion in a system. Temperature settings and temperature readings are all communicated to/from the DS1621 over a simple two–wire serial interface.Thecus is not bad, Joe, but still lightyears behind Synology. The hardware will likely work though I’m not sure if the RAM is supported. The SSDs will only work as cache — you need Synology SSDs for storage. Reply With that, let's proceed with the upgrade. For this post, I did the upgrades on a DS1821+, but the processes and parts are the same on a DS1621+. Synology DS1821+: RAM upgrade Our testing found the overall performance of the DS1621+ excellent, and it has plenty of grunt to run a wide variety of apps, host virtual machines, manage a IP camera system and more at the same time. The NAS was able to saturate a 1gBE connection no matter what else we had it doing, peaking at 729 Mbps reading and 710 Mbps writing. With the 10 GbE PCIe connection, it hit 3889 Mbps reading, and 2146Mbps writing, which is getting closer to the limits of the drive array. Synology DS1821+ vs DS1621 (left): The Storage Manager of the servers before and after an in-place upgrade using the same drives. Note the empty drive bays. Seamless transition between clustered servers in the event of a server failure to minimize the impact on applications.