The solid-state drive (SSD) has improved in performance overthe last few years, and the fastest examples have been edging ahead of harddisks in performance. However, Intel’s new SSDs have burst onto the scene likea streaker at a royal wedding. We uncover the secret behind their much fasterperformance.
CUSTOM CONTROLLER
The primary difference is found in the controller chip, which receives data from the S-ATA II bus and allocates it to the individual Flash chips. Whereas most manufacturers buy this chip fromanother manufacturer, Intel has created its controller from scratch, thanks toits in-house expertise in this kind of technology.
This is an important factor,as the controller chips of previous SSDs haven’t traditionally been able tohandle data at the speeds that Flash memory can deliver. Intel’s new controllerremoves this bottleneck, and interestingly, also supports Native CommandQueuing (NCQ), allowing it to stack up to 32 requests to reduce the latencycaused by the host PC waiting to issue new commands.
MULTI-LEVEL CELLS
The first Intel SSDs to hit themarket use multilevel cells (MLCs). These have multiple voltage states,allowing them to store more than one bit of data per cell. The most commonvariety has four states and can store two bits of data per cell.
In contrast,most of the SSDs currently on the market use single-layer cell (SLC) memory. AsMLCs store more data per cell, their capacity is cheaper, which is why Intel’s80GB SSD costs only a little more money than many 32GB models.
MLC technology isn’t perfect. Its write performance is slower than its read speed. Also, while all Flash memory cells deteriorateover time, the more complex voltage levels of MLCs mean that they’ll endure tentimes fewer write cycles than SLCs.
To combat this, Intel’s controller alsomakes efficient use of this reduced lifespan, so it can still quote a MTBF of1.2 million hours. This is lower than the two million hours often quoted forSLC-based SSDs, but equal to most enterprise-level conventional hard disks andtwice the usual value for consumer disks.
THE FUTURE
Not all Intel SSDs will use MLCs, however. Intel’s 32GB and 64GB X25-E Extreme willmake use of SLCs, boosting its write performance to 170MB/sec while maintaininga read speed of 250MB/sec.
Author: James Morris
Inside Intel's SSD