Performance figures are obtained from testing conducted with the device fully populated with drives under a continuous recording setup. Actual system capabilities may vary based on configuration, drive performance, enabled features, and the presence of additional workloads. SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV Create and edit documents, spreadsheets, and slides together with your whole team in real time. Easily migrate existing documents from other platforms and take ownership of your files in a secure private cloud. Learn more Figure 3. Synology DS918+ NAS (left) and DX517 expansion unit. The DX517 attaches to the DS918+ via an eSATA cable.

The actual performance may be lower than lab testing figure due to differences in server configuration, deployment, and the number of active operations.Synology reserves the right to replace memory modules with the same or higher frequency based on supplier's product life cycle status. Rest assured that the compatibility and stability have been strictly verified with the same benchmark to ensure identical performance.

Regarding data concerning tests with RAM expansion, all memory slots are installed with the maximum capacity of supported RAM. Anyway, i want to strictly separate the hdd's / storage from the expansion unit from the storage of the NAS to prevent data loss caused by NAS or DX failure. For example if the NAS or DX Powersupply fails or one of them just stops working, the RAID will be damaged, because suddenly several disks disappear at the same time. This is why i want to separate them. Unfortunately, it is not clear to me how to set it up the right way. I am not sure, if i have to create a separate storage pool with its own volume(s) for the new disks in the expansion unit, or if it will be enought to simply add the disks to the existing storage pool and create a new volume within this storage pool? I think the second option (adding drives to existing pool and creating a new volume in there) will distribute the data from volume 1 and 2 which are in the same storage pool, across all HDD's (These in the NAS and DX517) and will not separate them physically on the Harddrives, right? The performance of the mail system will slightly decrease in high-availability mode due to data synchronization between the two servers.My Synology DS918+ NAS was set up in February of 2018 with four 8 TB Western Digital Red drives. My video collection took up 17 TB (55%) of the available 30.7 TB of storage. I assumed the 13.7 TB of free space would last a long time (years) since I only buy a few titles per year. At the time of initial installation, my video collection was 71% DVDs, 29% Blu-rays, and 0% 4K Blu-rays.

The storage space on my Synology NAS (DS1520+) is running out. That's why I bought an expansion unit (DX517). Now I saw your video on youtube called "Understanding the Pros and Cons of the Synology DX517 Expansion - Part I". Unfortunately, part II and III have not been released yet. (Hope they will in future). I am sure that you may would have answered my question in video part 2 or 3. I am currently using only two of the DX517's five bays, for a total storage of 46 TB across six 8 TB drives, and a total occupancy of 25 TB (54%). Each 8 TB drive has 7.676 TB storage available. The NAS's operating system reserves 0.324 TB of space on each drive. Filling the remaining three bays with 8 TB drives would provide 69 TB total storage with a currant occupancy rate of 36%. Given the high cost of the DX517 (and I presume its rumored, impending replacement will be about the same), I'm wondering what people are using it for. I see some posters noting that they have two, or even three of these expansion units. You can save a few hundred dollars over another NAS unit, and I suppose you don't need to deal with more configuration, but why put money into a DX517 instead of larger drive sizes? I have not noticed any speed or performance differences when loading files into the expansion unit or when streaming video from the expansion unit.I upgraded from a Drobo to a ds1621+ a few months ago and it has been great! I made what seems to be a common mistake (given other posts here) and assumed that the DX517 expansion unit would seamlessly give me another five drive bays for when I was ready to expand. I have accumulated a number of hard drives in the process of upgrading and like the idea of putting them to use, but in reading about the DX517 it seems it'd be fine to create a second storage pool, but it's extremely risky and poor practice all around to spread your volume between the drives in the main NAS unit and drives in the expansion unit. This sub has talked me out of that idea - I don't want to risk it. Performance figures are obtained through SMB sequential throughput tests using Windows Server 2016 Datacenter on a SSD cache can be enabled by using 2.5" SATA SSD drives in standard drive bays or without occupying drive bays by installing Synology SNV3400 Series M.2 NVMe SSD drives through the built-in M.2 slots. SNV3400 Series M.2 NVMe SSD drives can also be used to create SSD storage pools. Drives are sold separately. PCIe add-in cards, expansion units, and storage drives are sold separately. Refer to the compatibility list for compatible devices.