Extend the standard 3-year hardware warranty of your DS1621+ with 2 more years of Synology-certified support and premium services that help you recover faster in the event of disaster. 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?

Seamless transition between clustered servers in the event of a server failure to minimize the impact on applications. Creating M.2 storage pools requires the use of Synology-verified SSDs, which are rigorously tested under extreme temperature conditions. Thermal parameters for SSDs and NAS units are fine-tuned to ensure optimal management of thermal conditions under I/O-intensive environments. ( Learn more) Performance figures obtained through internal testing by Synology. Actual performance may vary depending on the testing environment, usage, and configuration. See performance charts for more information. Sequential write throughput in MB/s when using a 10GbE SMB connection. Tested on an all-flash volume with Synology SAT5200 flash drives. Figure 3. Synology DS918+ NAS (left) and DX517 expansion unit. The DX517 attaches to the DS918+ via an eSATA cable.

During testing, the maximum number of SSDs supported by this model is installed in a RAID 5 configuration.

I have not noticed any speed or performance differences when loading files into the expansion unit or when streaming video from the expansion unit. Performance figures are obtained through SMB sequential throughput tests using Windows Server 2016 Datacenter on a Managed from DiskStation Manager on the host NAS, the additional bays in the DX517 are immediately ready to be used once connected. On-the-fly volume expansion ensures that storage and services on the host are not interrupted during volume expansion. In two years time, the NAS's 45% storage vacancy had dwindled to 19%. I thought it would be wise to proactively increase storage space. My first thought was to replace the DS918+ with a Synology eight-bay DS1819+ equipped with 10 TB Western Digital Red drives. The figures are based on Synology internal testing. Each performance test is done individually. No other services or applications are processed at the same time.

5-bay 3.5"/2.5" SATA expansion

SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, Fibre Channel, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV 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.

This may be one of those cases of "if you have to ask, it's not for you," but I raise the question mostly because I still really like the idea of the expansion unit and still think it might be something I could make use of - I'm just trying to recalibrate my expectations and figure out if it's still something that could be useful for me. Synology only guarantees full functionality, reliability, and performance for Synology drives listed on the compatibility list. The use of non-validated components may limit certain functionality and result in data loss and system instability. applies to files indexed or hosted by Synology Drive. For file access through other standard protocols, refer to the File Services section above) 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. Extend the standard 3-year hardware warranty of your DS1821+ with 2 more years of Synology-certified support and premium services that help you recover faster in the event of disaster.SMB1 (CIFS), SMB2, SMB3, NFSv3, NFSv4, NFSv4.1, NFS Kerberized sessions, iSCSI, HTTP, HTTPs, FTP, SNMP, LDAP, CalDAV Please select Synology memory modules for optimum compatibility and reliability. Synology will not provide complete product warranty or technical support if non-Synology memory modules are used for memory expansion. Synology DS1621+ is a powerful and compact 6-bay network attached storage solution designed to store and protect critical data assets. Today’s growing amount of unstructured data requires smarter and increasingly higher performance methods of storing, accessing, and collaborating. Designed for scalability, the DS1621+ enables you to start small, then expand as your data grows.