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It's not the most powerful or scalable 2U server in Dell's PowerEdge range, but the R520 is still a quick, capable and affordable dual-socket platform that can be configured to handle a variety of both datacentre and distributed office workloads.
Dell's flagship PowerEdge R720 with its top-of-the-range Xeon processors isn't the only 2U dual-socket server in its PowerEdge family. For those with less demanding requirements there's the R520, designed around more modest silicon, with slimmed down memory and storage options to match.
Design Over the years we've come to expect a lot of Dell's rack-mount servers — especially when it comes to chassis design. The R520 doesn't disappoint in this respect: the chassis is extremely well built, and heavy, topped by a full-length lockable lid giving access to a minimalist and spacious interior.
On the downside, orange — the colour used by Dell to indicate hot-swap components — is sadly absent. The six cooling fans, for example, have blue markings, which means they can only be changed with the power off. Opt for redundant power, however, and the power supplies themselves can be hot-swapped: our review system shipped with two 495-watt units to suit the configuration provided.
Alternative 750W and 1,100W supplies are also available, as is a DC power option if required.
CPUs and RAM Any of the processors from the Xeon E5-2400 line-up can be specified when ordering the Dell server, with four-, six- and eight-core implementations on offer here, plus a variety of feeds, speeds and power envelopes.
Our review server came with a pair of E5-2430 chips, clocked at 2.2GHz, with 15MB of L3 cache and a TDP rating of 95W. These have six cores each which means, with multithreading, that Windows sees 24 logical CPU cores.
Performance is very much down to processor choice, but running the Geekbench 64-bit processor benchmark our server returned a score of 18399. Quite a bit down on the 24329 of the PowerEdge R720 but, as that was equipped with 8-core E5-2600 processors, hardly surprising.
There's also much less room for RAM in the R520, with just 12 DIMM slots on the motherboard — half the number to be found inside its bigger R720 brother. Still, with a ceiling of 192GB that's a lot better than the 128MB supported by the old R510, enabling the server to be configured to suit a variety of applications — including memory-hungry server virtualisation — without breaking the bank.
Dell sent us 24GB of RAM in the shape of six 1,333MHz DDR3 modules. These had the ECC option to be expected on a server, but processor choice meant that a lower 1,067MHz clock was employed.
With some processors you can specify 1,600MHz RAM, and all setups can have memory mirroring and sparing configured to protect against memory failures.
Storage options When it comes to storage, the R520 chassis can be ordered with fittings for either four or eight hard disks with — depending on what you specify — either one or two banks of front-mounted hot-swap bays. These can accommodate 3.5in. or (using special trays) 2.5in. drives with the usual choice of SATA, SAS and SSD disks cabled to Dell PERC RAID controllers.
A RAID controller, however, is entirely optional — and for customers with existing network storage somewhat superfluous as, on such deployments, local storage will mostly be used for the operating system. The review system, therefore, came with the minimum four bays with just one drive installed — a 100GB SATA SSD, on which we installed Windows Server 2008 R2 for our tests.
There was no RAID card either. Instead, the SSD was cabled to the 4-port SATA controller on the motherboard, although Dell does provide software RAID for this (assuming you're running Windows and have more than one disk) — an option it refers to as PERC S110, adding support for RAID 0, 1, 5 and 10.
Unfortunately the Dell Express Flash PCIe SSDs offered as an option on the R720 aren't available for this server. You can, however, specify both nearline and dual-ported SAS drives with spin speeds of up to 15,000rpm. External host bus adapters can also be ordered with four PCIe 3.0 slots available to accommodate these and other plug-in cards.
Networking and other options You can't plug GPU accelerator cards into the PCIe slots in the R520, as you can in the R720, but these slots can be used to provide additional network ports. And that's over and above the two Broadcom Gigabit interfaces already on the motherboard — one of which carries additional responsibility for in-band remote management over the LAN.
As with other 12th-generation PowerEdge servers, the R520 features the latest iDRAC7 technology, with an improved web interface giving easier access to important data plus additional power monitoring and management features.
Our review unit came with basic command-line remote management only, although for £120 (ex. VAT) this can be upgraded to the iDRAC7 Express implementation with access to the latest Dell Lifecycle controller. Beyond that, the iDRAC7 Enterprise upgrade (a further £170 ex. VAT) adds a graphical remote console and virtual media plus a dedicated Gigabit port for remote monitoring and management.
Finally, there's a slot on the motherboard for an embedded hypervisor, which takes the form of a dual SD card module, the second card providing extra redundancy should one of the hypervisors fail. These can be preloaded with VMware or Citrix hypervisors, but there's no provision for Microsoft's Hyper-V.
Quick and quiet With its single SSD, the PowerEdge R520 we tested was eerily quiet much of the time — even when pushed to do some real work. As a result, power consumption was low, and could be trimmed further if you're prepared to accept slightly slower processors.
The R520 is not as quick as the R720 and nowhere near as scalable, but it's no slouch; it's an affordable server that could be used for a variety of purposes, from basic file and print sharing through to mid-range virtualisation and private cloud duties.