Synology RackStation RS2421RP+ review: AMD to the rescue

This capacious rack NAS offers a big speed boost over its Atom-powered predecessor

Synology RackStation RS2421RP+

IT Pro Verdict


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    Good value

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    AMD Ryzen CPU

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    Clear performance improvements

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    PCI-E slot

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    Classy DSM software


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    Restrictive HDD/SSD compatibility list

Targeting storage hungry SMBs, Synology’s RackStation RS2421+/RP+ 12-bay appliances deliver a strong combination of power and capacity. Inkeeping with Synology’s two-year refresh cycle, they step up as replacements for the RS2418+ models and claim to offer a significant performance boost.

This is undoubtedly achieved by kicking Intel out and replacing it with AMD – something Synology is now doing with increasing regularity. Out goes the elderly 2.1GHz Atom C3538 CPU in favour of a more youthful quad-core 2.1GHz Ryzen V1500B, and another bonus is support for server-grade ECC memory.

On review, we have the RS2421RP+, which extends its 2U rack chassis depth by an extra 26mm over the standard model to accommodate a pair of 350W hot-plug PSUs. These do bump the price up by nearly £400, but it’s worth having the extra redundancy if you’re running business-critical storage services.

Synology RackStation RS2421RP+ review: Build quality and hardware

Build quality is excellent with the appliance presented in a sturdy steel 2U chassis. The metal drive carriers can’t be key locked but a small tab on each one can be pushed across to stop them being accidentally popped out, and the triplet of hot-plug cooling fans are easily accessed without powering off the appliance by removing a small hatch in the lid.

There isn’t much to see under the lid; the embedded Ryzen CPU is topped off with a chunky passive heatsink and partnered by a pair of long DIMM memory slots, with one occupied by a 4GB module. Memory is the only area where the RS2418RP+ wins out, as it comes with four DIMM slots and supports up to 64GB – twice that of its successor.

Synology RackStation RS2421RP+ backup software

There are no changes in the port department, with the rear panel sporting four Gigabit, dual USB 3 and one high-speed Infiniband port for expanding outside the box with Synology’s RX1217/RP 12-bay disk shelf. Further expansion is facilitated by a spare PCI-E slot, but the adapter compatibility list is restricted mainly to Synology’s 10GbE and 25GbE network adapters plus its M.2 NVMe SSD modules.

You’ll want to avoid deviating from the HDD and SSD compatibility list too, as the RS2421RP+ is one of a number of Synology’s enterprise-class appliances that are restricted mainly to its own storage devices. For testing, we loaded up four 8TB HAT5300 SATA hard disks which, unsurprisingly, were accepted without any complaints.

Synology RackStation RS2421RP+ review: Software and apps

Synology is promoting the RS2421RP+ as a versatile storage server and its DSM software seals the deal as it’s packed to the rafters with apps. These cover everything from file serving, collaboration, surveillance and virtualization to backup, data protection and private clouds.

Local appliance data is protected by Btrfs snapshots on NAS shares and iSCSI LUNs, which can be scheduled or run manually from the Snapshot Replication app. Hyper Backup looks after all your local, remote, Rsync, cloud and iSCSI LUN backups from a single console and integrates neatly with Synology’s optional C2 Backup cloud service for essential off-site storage.

The slick Active Backup Suite turns the appliance into a fully centralized backup vault. The free Active Backup for Business (ABB) component can secure servers and workstations plus VMware and Hyper-V virtualization hosts and all their VMs. The suite also provides separate apps for protecting Microsoft 365 and Google Workspace.

You’ll need to upgrade the base 4GB of memory to make the most of it, but the Virtual Machine Manager app can host just about any OS you care to name, including virtualized versions of DSM with the price including one license for the latter. It’s easy to use; we created a Windows Server 2019 VM from an ISO file in only 20 minutes and could back it up by taking regular scheduled VM snapshots.

Synology RackStation RS2421RP+ VM manager

Synology RackStation RS2421RP+ review: 10GbE performance

For our high-speed tests, we installed Synology’s E10G21-F2 dual-port fibre 10GbE adapter in the appliance and hooked it up to a Dell EMC PowerEdge T640 Xeon Scalable tower running Windows Server 2019. For comparison purposes, we took the numbers we achieved when we reviewed Synology’s 12-bay DS2419+ desktop appliance, which has an identical hardware spec to the RS2418+.

The RS2421RP+ clearly delivers on its performance promises. A share mapped to the server returned Iometer sequential read and write speeds of 9.3Gbits/sec and 8Gbits/sec – the DS2419+ was measured at 9.2Gbits/sec for reads and only 4.4Gbits/sec for write. We saw the same improvements in our real world tests with drag and drop copies of a 25GB file recording average read and write speeds of 5Gbits/sec and 4.9Gbits/sec – increases of 7.6% and 46%.

Our backup test secures a 22.4GB folder containing 10,500 small files to the share, and this was 5% faster with the rack-mounted unit compared to the DS2419+. The Ryzen CPU is more efficient than the Atom for encryption duties too, as copying our 25GB file to an encrypted share averaged a speedy 2.6Gbits/sec – a 70% improvement over the DS2419+.

It was the same story for IP SANs: Iometer reported sequential reads and writes of 9.2Gbits/sec and 8.2Gbits/sec for a 500GB iSCSI target as opposed to 8Gbits/sec and 6.3Gbits/sec for the DS2419+. With a dual 10GbE MPIO to the target, read speeds ramped up to 18.3Gbits/sec and although writes fell slightly to 7.2Gbits/sec, these are still 46% and 25% better.

Synology RackStation RS2421RP+ review: Verdict

The RackStation RS2421RP+ is a versatile NAS appliance that has the storage capacity to please SMBs with big backup demands – and for those with even bigger appetites, Synology offers a 16-bay RS2821RP+ version. Its AMD CPU is clearly a much better performer than the Atom in its predecessor, and it delivered speed increases right across the board in our tests.

Pay close attention to Synology’s storage compatibility list though, as using any drives other than those listed will generate warnings in the web console. Nevertheless, Synology’s HAT5300 drives perform very well and its DSM software offers a superb range of features with a wealth of free data protection apps.

Synology RackStation RS2421RP+ specifications

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Chassis2U rack chassis
CPUQuad-core 2.2GHz AMD Ryzen V1500B
Memory4GB ECC DDR4 (max 32GB)
Storage12 x SATA LFF/SFF
RAIDRAID0, 1, 10, 5, 6, JBOD, SHR
Expansion1 x PCI-E 3
Network4 x Gigabit
Other ports2 x USB 3, 1 x Infiniband
Power2 x hot-plug 350W PSUs
ManagementWeb browser
Warranty3 year limited
Dave Mitchell

Dave is an IT consultant and freelance journalist specialising in hands-on reviews of computer networking products covering all market sectors from small businesses to enterprises. Founder of Binary Testing Ltd – the UK’s premier independent network testing laboratory - Dave has over 45 years of experience in the IT industry.

Dave has produced many thousands of in-depth business networking product reviews from his lab which have been reproduced globally. Writing for ITPro and its sister title, PC Pro, he covers all areas of business IT infrastructure, including servers, storage, network security, data protection, cloud, infrastructure and services.