Toggle my DDR
There are two kinds of memory in the Samsung 830 Series SSD: a 256MB DRAM cache chip and an array of Toggle DDR NAND. Backed primarily by Samsung and Toshiba, Toggle DDR NAND is an alternative to the ONFI flash specification supported by Intel, Micron, and others. Both standards are JEDEC-approved, but they go about things a little differently.
Toggle DDR NAND is similar to synchronous ONFI memory in that reads and writes can be executed on both the rising and falling edges of a data query strobe. This strobe is activated only when transfers are taking place, making Toggle NAND potentially more power-efficient than the ONFI stuff. In order to hit a similar double data rate, synchronous ONFI NAND uses an external clock cycle in addition to its data strobe.
Samsung's marketing materials for the 830 Series reveal that the NAND dies are capable of transferring data at speeds up to 133Mbps. Surprisingly, that's the same data rate quoted for the Toggle DDR chips in the old Samsung 470 Series. 133Mbps is the maximum speed for the first-generation Toggle standard, while Toggle DDR 2.0 promises per-chip data rates as fast as 400Mbps.
Although the 830 Series' individual NAND dies don't appear to be any faster than the ones found in Samsung's last-generation SSD, the individual transistors are definitely smaller. The last-gen NAND was manufactured on a 32-nm process, but the new drive uses memory built on a "20-nanometer-class" node. Samsung wouldn't be more specific about exactly where its fabrication technology falls inside the 2x-nm spectrum.
Our 256GB sample features eight NAND packages arranged on the same side of the circuit board as the controller and cache memory. According to Samsung's decoder ring, those K9PFGY8U7A-HCK0 packages offer 256Gb spread across eight NAND dies, resulting in a 64 x 32Gb die configuration for the drive as a whole. SSDs in the same size range usually achieve their capacities with 32 x 64Gb die configurations, so the Samsung 830 Series has an apparent edge in die-level parallelism.
In our look at SSD performance scaling across multiple capacities, we learned that increasing the number of NAND dies on an SSD can dramatically improve its performance. We also saw that performance can be improved by using higher-density dies, so I wouldn't draw any conclusions based on die counts alone.
Do note the high die-per-package count, though. The NAND packages in most of the SSDs we've tested have one or two dies each. Samsung crams in eight dies per package on the 830 Series 256GB, and the NAND packages in its 470 Series predecessor have a similar die density. More dies per package means fewer packages per drive, which enables smaller and slimmer form factors. This is the first 256GB SSD we've seen mount all its components on only one side of the circuit board, leaving an eerily naked underbelly. The Samsung 470 Series is also a bit of an oddity on the form-factor front; although the 256GB model comes in a 2.5" case, the circuit board is about the same size as a 1.8" drive.
|Capacity||Max sequential||Max 4KB random||Price|
|64GB||520MB/s||160MB/s||75,000 IOps||16,000 IOps||$110|
|128GB||520MB/s||320MB/s||80,000 IOps||30,000 IOps||$220|
|256GB||520MB/s||400MB/s||80,000 IOps||36,000 IOps||$360|
|512GB||520MB/s||400MB/s||80,000 IOps||36,000 IOps||$800|
With NAND packages of a similar density, Samsung could probably build the smaller versions of the 830 Series on single-sided 1.8" circuit boards. We're still waiting to hear back from Samsung on the die configurations for other sizes in the family.
Samsung's performance specifications give us a sense of what to expect from the 256GB model's siblings, though. The 512GB drive doesn't appear to be any faster, and the 64GB variant is purportedly quite a bit slower. We tend to prefer 128GB drives, and that looks like a pretty good spot in the lineup. The 128GB model should offer roughly double the write performance of the 64GB version without being too big of a step down in performance from the 256-512GB flavors.
Regardless of the capacity, the Samsung 830 Series comes in a couple of fancy retail kits: one with mounting hardware for desktops, and the other with a SATA-to-USB adapter meant for notebooks. Each retail package includes a copy of Norton Ghost and a download code for the PC version of Batman: Arkham City. Bundling a hot new game with a solid-state drive is a little bit weird, especially since most notebook users will struggle to run Arkham City at playable frame rates. If your PC is up to snuff, the game is pretty awesome. After spending only a few hours in Arkham City, I can tell you that all the critical acclaim is well deserved. Even those with no desire to play the game should be able to find a grateful recipient for the coupon code.
Before sitting down to test Samsung's latest, I realized that I'd yet to hear any complaints about the company's SSDs losing data, bricking after firmware updates, or spitting out BSOD errors. Every major SSD maker seems to have been hit with one bug or another, and for a moment, I thought Samsung might be immune. No such luck. The release notes for the latest firmware list improvements to "compatibility and stability," and a prior update fixed a "blue screen, hang problem."
Samsung SSDs haven't been entirely devoid of issues, but we also haven't heard of any widespread problems. Perhaps that's because the drives and their firmware are more robust. Then again, it might be because the notoriously vocal enthusiast community has favored other solutions. There are only a few hundred user reviews of Samsung's 470 and 830 Series SSDs on Newegg. Meanwhile, the very same retailer has thousands of user reviews of just OCZ's latest SandForce-based SSDs.
At least Samsung's SSD Magician software makes downloading and installing firmware updates a snap. This application can secure-erase drives and perform various system optimizations. It also features an overprovisioning tool that can increase the amount of NAND capacity used as "spare area" by the controller. Other SSDs allow their overprovisioning to be tweaked simply by creating a partition smaller than the total size of the drive, but kudos to Samsung for wrapping up this and other functionality in a tidy little app.
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