Synology DiskStation DS620slim Review

Many Synology fans were disappointed last year when the highly anticipated DS619slim appliance turned into vapourware. However, those still dreaming of a mini 6-bay SSF NAS appliance have had their patience rewarded as the newly announced DS620slim exists and is in our lab on review.

Measuring 121 x 151 x 175mm (HWD) and weighing only 1.4kgs unpopulated, the DS620slim supports up to six SFF SATA hard disks or SSDs mounted in plastic hot-swap carriers at the front. What lies beneath is of equal interest as it offers a far superior specification to the palm-sized DS419slim.

Inside is a dual-core 2GHz Intel Celeron J3355 partnered by 2GB of DDR3L memory upgradeable to 6GB. Unlike the Armada CPU in the DS419slim, the Celeron is a 64-bit model so the appliance can run most of Synology’s apps.

The Celeron also has an embedded Intel HD Graphics 500 GPU making it well-suited to running multimedia apps with 4K video transcoding. Other hardware features are dual Gigabit and USB 3 ports at the rear.

Check the compatibility list

The appliance’s 64-bit Celeron CPU brings snapshot and replication services into play

The DS620slim is essentially a miniature version of Synology’s standard desktop appliances and employs the same sturdy metal charcoal-black chassis. The plastic drive carriers have spring-loaded release levers each with small Allen-key style locks to stop them being accidentally popped out.

LED indicators across the top show the status of the system and network ports while the drive carriers also incorporate status LEDs. A single 8cm diameter fan at the rear handles all cooling and we found the DS620slim to be whisper-quiet.

Deployment initially stalled as we fitted four 1.92GB Seagate IronWolf 110 SSDs which the quick start wizard promptly ignored. We should have checked the HDD/SSD compatibility list first as we found that unlike the DS419slim, the DS620slim only currently supports the 240GB IronWolf 110 models.

Swapping over to three 480GB Intel Enterprise SSDs proved to be more effective with the wizard swiftly installing the latest DSM software and requesting that we secure administrative access with a new account and password. The wizard then created a fault tolerant SHR (Synology Hybrid RAID) array from all the SSDs.

Big performance boost

For performance testing, we used a Dell PowerEdge T640 Xeon Scalable tower server running Windows Server 2019 and can confirm the DS620slim is a lot faster than the DS419slim. Running Iometer on a NAS share mapped to the server returned raw sequential read and write rates both of 113MB/sec.

With another Xeon Scalable Windows server connected to the appliance’s second Gigabit port, we recorded cumulative Iometer read and write rates of 226MB/sec and 198MB/sec. In this test, the DS419slim only managed a cumulative 110MB/sec write rate with its CPU hitting 99% utilization – the DS620slim was nearly twice as fast with CPU utilization averaging only 50%.

Real world performance was also superior with 25GB file copies averaging read and write rates of 113MB/sec and 110MB/sec while our 22.4GB backup test folder was secured to the share at 81MB/sec. The Celeron’s hardware encryption engine was also more efficient as copying our 25GB test file to an encrypted folder returned a speedy 92MB/sec – three times faster than the DS419slim.

IP SAN performance is up there too, with a 250GB target returning Iometer read and write speeds of 113MB/sec and 109MB/sec. Ramping up the pressure with a dual Gigabit MPIO link to the target saw speeds increase to 226MB/sec and 195MB/sec. 

Backup and protect

The new Drive app offers improved file management, synchronization and collaboration

To get the best out of the DS620slim as a backup appliance will require the use of high capacity SFF SATA hard disks but rest assured, its 64-bit Celeron ensures there are plenty of apps to play with. Select BTRFS during volume creation and you can use the Snapshot Replication app to manage on-demand and scheduled NAS share plus thin-provisioned iSCSI LUN snapshots and run remote replication to other Synology appliances.

The standard Hyper Backup app manages all local, remote, cloud and Rysnc backups of appliance data from one console. We tested the latest beta v2.2 which adds support for new S3 storage classes, individual file backup and summary views of all backed up file versions.

Synology’s Active Backup for Business (ABB) app is a class act it this provides backup, restore and disaster recovery services for Windows servers and workstations along with VMware vCentre and ESXi hypervisors. Managed from a single console, ABB requires agents loaded on your Windows systems where it provides backup scheduling along with slick file and folder plus bare-metal system restore facilities.

More apps of distinction

Synology provides plenty of useful multimedia apps

Multimedia fans will find plenty to like with the free Video, Audio and Photo Stations. We use the Audio Station a lot as we can link the DS Audio iOS app on our iPad to it and access our music locally and remotely over the internet.

The Photo Station keeps all your prized pictures neatly organised while the Moments app adds useful features such as image recognition techniques to sort them into categories such as people, subjects and places. We also use the iOS Moments app on our iPad as it automatically backs up all our photos to the NAS appliances and will send new photos to it as soon as they have been snapped.

Film buffs have the Plex Media Server, Logitech Media Server and Synology’s Video Station. The latter is easy to use as it loads a separate web console, provides streaming and transcoding services and offers a complete media library.


We were impressed with the DS620slim as it delivers all the features you’ve been waiting for in an SFF NAS appliance but do check Synology’s compatibility list to make sure your choice of HDD or SSD is supported. Only costing $100 more than the DS419slim, it delivers a vastly superior performance, has a much higher storage capacity and its 64-bit CPU allows it to run virtually every app Synology has to offer.

Build quality

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