What is the benefit of using flash memory in the Macbook Air?
How does the use flash memory compare to SSDs? What are the benefits?
The Macbook Air uses an SSD. Apple markets it as merely flash memory because in the consumer market there are only two storage types - flash and hard drives. The typical consumer Apple is aiming for does not know what SSD is, nor do they care. But they do know what a "flash drive" is, and due to aggressive marketing they believe it's better than the alternative.
It's a custom form-factor SSD, but it uses a SATA flash controller, and the Air reads it just as if it were any other SATA drive. OS X does, however, understand it as an SSD and treats it slightly differently from a hard drive in order to use it to its full potential, but in every other respect it's just a custom form factor SSD.
The reason Apple uses a custom form factor SSD is for size, weight, and - most important to Apple - cost.
They have both Toshiba and Samsung on the line for supplying these SSDs. When they get a poor price from one, they go to the other. They need this because the SSD is one of the few things in the Air that requires custom PCB layout and comes from multiple suppliers. The pinouts and circuitry are different between the samsung and toshiba flash controllers, so they can't build them into the main PCB as Apple would prefer, without locking them into one vendor or the other.
The flash market is so volatile right now that they can't lock themselves into just one supplier, especially since some 80% of Apple's revenue comes from products that use copious amounts of flash. If they thought they could get a better price manufacturing their own flash, they'd have their own plant - or ten. Instead it's cheaper to play the major flash producers against each other to get the lowest cost.
So:
- The Storage in the Air is a SATA interfaced SSD
- It's not on the main PCB to give them the ability to use different parts from different suppliers
- It's not a 2.5", 1.8", or SATA slim interface because they needed it to be smaller - they designed their own interface, but it's still SATA, just with a different low insertion force connector
- They aren't using the latest and greatest chipsets due to cost and power consumption
- They aren't using hard drives due to size, weight, and power consumption
Try erasing free space (from Disk Utility, on the bottom left corner of the "erase" tab of your drive), and then enable trim (via Trim Enabler).
More than likely this drop in performance is caused by the SSD having to clear memory before being able to write to it. Flash memory can only bring bits up (from 0 to 1), meaning that over-writing a non-zero byte requires first erasing the whole byte, then bringing up whatever bits are needed. This means that 2 operations are needed (erase, write) rather than just 1 (write). TRIM helps improve performance by actively zeroing out memory locations that have been deleted during idle times, allowing for a single write operation to be sufficient for writing to that location. Erasing free space will do the same thing, but it's a one time deal, whereas TRIM works in the background to keep it all tidy.
Best Answer
From what I understand you don't need to worry about that. Those limits are just as indication and you won't be reaching those in years (at least with newer SSDs). If I remember right, my Crucial M4's lifespan is over 5 years under heavy daily use (like 40gb write per day).