The DS1621+ comes populated with 4GB of ECC DDR4 in one slot of two slots, and can support up to 32GB. Despite the higher price, it’s great to see the ECC RAM used for improved protection against data corruption. In 2002, Dallas Semiconductor was acquired by Maxim Integrated, a multinational semiconductor company, and became a subsidiary of Maxim. Dallas Semiconductor was an American company that was founded in 1984 and was a supplier of mixed-signal and digital semiconductors. Usable capacity for each volume will be lower than the maximum volume size and is dependent on the filesystem and the amount of system metadata stored. You will need two drives if you want to cache for both writing and reading -- so it's a good idea to get two.

As I mentioned in the review of the DS1621+, in most cases, SSD caching upgrade is unnecessary and won't increase the server's general copy speeds. 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

Works best with Synology drives

Synology SNV3400 series M.2 NVMe SSD drives can be installed through the built-in M.2 slots to enable SSD caching or create SSD storage pools. Drives are sold separately. In a way, this post is about Synology hardware upgrades, specifically in RAM, storage, and 10Gbps network speed. In other words, if you're looking for the best 10Gbps NAS for the home (or small office), you're at the right place. You also get three USB 3.0 ports (one on the front) plus dual eSATAs. The latter is used for adding external drive bay expansions, and an extra 16 bays and 108TB total is possible. The NAS CPU itself has no fan on the heatsink, but the DS1621+ has dual rear 92mm fans that provide decent airflow, and keep your drive array from getting too hot.

The DS1621+ has a PCIe slot, which supports a range of 10GbE networking cards. (Image credit: Future) For my case, though, I used the first option for my DS1821+ and the third for my DS1621+ -- two ports are always better than one. But no matter which card you get, the installation is the same. Extra: Synology DS1621+ to DS1821+ in-place upgrade For performance testing, we installed four of Toshiba’s new air-filled 4TB MG08-D series of hard disks. These are aimed specifically at business users that are more focused on cost and reliability, and don’t need the massive capacities of helium-filled spinners. To test caching efficacy, we fitted two 480GB Kingston DC1000B enterprise-class M.2 NVMe SSDs and although neither these nor the Toshiba drives feature on Synology’s compatibility list, the DSM software allowed us to use them. If you're using the DS1621+ and want to upgrade to the DS1821+ to take advantage of the two extra drive bays, the process is the same as when you migrate from one Synology server to another.The 5-bay DX517 expansion unit uses an eSATA connection, which caps at 5Gbps, to connect to the server. In our testing we saw performance for random access improve up to 2.1x using SSD caching, but for most uses it was a lot lower. The biggest real world difference was when running multiple virtual machines, which were a lot more responsive with SSD caching. We also tested with 16GB of RAM, which helped a lot for memory heavy applications. Hardware specifications: Synology DS1821+ vs DS1621+ Synology DS1821+ vs DS1621+: Hardware upgrades are (almost) a must 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.

More caution is needed when selecting a 10GbE adapter, however, as Synology is rapidly shrinking its third-party hardware compatibility list and focusing more on its own solutions. When we installed the same Emulex dual-port 10GbE adapter we’d used to test the DS1618+, the DS1621+ hung during the boot phase and would only accept a dual-port Intel X520 10GbE adapter. Synology DiskStation DS1621+ review: 10GbE performance

Applications include thermostatic controls, industrial systems, consumer products, thermometers, or any thermal sensitive system