Closer Look: Samsung 840 Pro SSD

Samsung created a winner with the 830 SSD, but they haven’t been sitting back on their laurels. Samsung updated the successful MCX controller to a new controller, called MDX. Samsung also switched ARM cores from the ARM9 cores used in the 830 to three ARM Cortex-R4 cores in the 840 and 840 Pro SSDs. The R4 cores also run at a clockspeed of 300MHz, quite an increase over the 220MHz clockspeed on the 830 SSD. The 840 and 840 Pro SSDs use Toggle Mode 2.0 memory interface, rated at up to 400Mbps and manufactured on a 21nm node. The old 830 SSD used Toggle Mode 1.0 NAND at up to 133Mbps, making the 840 interface roughly three times faster.

While the 840 and the 840 Pro both use the MDX controller, which boasts advanced geometry and lower power consumption, they use different flash memory. The Samsung 840 Pro SSD uses Samsung’s proven Toggle Mode MLC Flash memory. The 840 SSD, on the other hand, opts for the slower and less expensive, albeit newer Triple-Level Cell (TLC) NAND flash.

The Samsung 840 Pro SSD comes in 128GB, 256GB, and 512GB flavors currently, with a possible 64GB version coming along in the future. Since the 840 Pro is intended more for a commercial and possibly enthusiast market when compared to the 840 or 840 EVO, the 64GB version doesn’t really make as much sense.

The 256GB and 512GB models of the 840 Pro contain a 512MB of LPDDR2-1066 cache. The 128GB model has 256MB of cache. The cache, at 1066MHz is another upgrade from the 256MB of LPDDR2-800 cache on the 830 SSD. The 840 Pro also houses another handy little upgrade in the form of full drive encryption via AES-256.

The Samsung 840 Pro SSD is adorned with a flat, black, matted finish. Other than that, it looks just like previous Samsung SSDs, unadorned with anything besides the Samsung logo and an orange square patch. Well, there is also a tiny arrow pointing you toward the SATA connections. The 840 Pro SSD comes in the now-standard 2.5” 7mm form factor. That size will fit current laptops, but you may need an adapter if your laptop is older and requires a 9mm drive.

The biggest news regarding the Samsung 840 Pro, however, it its relatively recent adoption into the family of Samsung SSDs that support RAPID mode. RAPID mode is very impressive, and warrants a closer look.

RAPID stands for Real-time Accelerated Processing of I/O Data and it starts speeding up your reads and writes as soon as it is enabled. RAPID mode is designed to improve random I/O performance for small sizes of data at low queue depths. The icing on the cake, however, is that RAPID mode tries to analyze application and data usage in order to optimize I/O for frequently used data, which they call ‘hot data’.

RAPID mode analyzes all storage related activity by inserting itself as a filter driver in the Windows storage stack. By analyzing all storage-related activity, RAPID mode can grab hold of spare resources in the form of RAM to cache the ‘hot data’ it has identified, thus greatly improving read performance. RAPID mode also tries to optimize write performance by closely controlling the coordination between the CPU and the SSD.

RAPID mode actually acts similarly to your system cache, and its main function doesn’t even deal with the SSD at all. Unlike the system cache, though, that just stores recently accessed data, RAPID mode provides RAM caching based on a number of factors, like access frequency, file types, system status, and RAM availability. RAPID mode also caches the ‘hot data’ across sessions and reboots.

RAPID mode optimizes write performance by identifying the frequent micro-transactions that take place quite often behind the scenes, like log updates or indexing. RAPID mode looks for low-queue-depth random write requests and flags them to be combined together into a single, larger, higher queue-depth request and written in parallel across the available NAND die. Since SSDs favor parallel processing, this action can greatly reduce the time required to complete all those individual micro-transactions.

Samsung 840 Pro Features

Source: Samsung