Something I don't get about SSD's
 

I know that SSD's are very popular as boot drives because they are fast and reliable, but why would you instal a 128GB SSD as boot drive? An OS doesn't take up that much space?

Does anyone use them to store data as well instead of an HDD? And why do they come with relatively small capacity compared to the HDD's? Are they limited by their technology or are they just too expensive?

Thanks guys. :)

Size is limited by cost -- and the willingness of the market to pay it.

You can buy SSDs with capacities measured in terabytes. However, they come with pricetags measured in thousands. The cheapest SSDs today generally run around $0.70 per gigabyte. HDDs in contrast cost as little as $0.04 per gigabyte.

The real benefit for SSDs for the home user is quick retrival of small files. Thus you want not only the OS but your various applications, including games, on your SSD. Load a few 15-20 GB games onto a drive and even a 128GB capacity is quickly strained. It is generally more cost effective to buy a larger single SSD than a couple of smaller drives, plus because of the way SSDs work larger drives enjoy a significant performance advantage.

As for data storage, retrival of sequential data from large files isn't greatly affected by the speed difference between SSDs and HDDs. When playing a movie or a song, you don't need to deliver the whole file in three seconds. As a result, those files which cost the most to store benefit the least from expensive SSD storage. There's little to gain from spending ten or twenty times as much to store your media files.

I see, so you would actually recommend having the OS and software (games, Office, iTunes etc) on the ssd for fast load times but actual files (office documents, songs etc) on the HDD because they won't gain much benefit from loading from an ssd, is that correct?

I keep my personal files on the ssd as well. Like office docs and pictures. Faster and there is room for them. A large mechanical drive is there for movies and music and stuff. Things that get put there once and then gets read from. You don't want to fill your ssd though, they keep in top shape if you don't fill past 80%. The firmware will use that space for wear leveling and other cleanup functions.

One thing I have done with my SSD's as well (to give the controller more room for 'wear leveling' is that I only tend to format 85-90% of a drive's space.

SSD's storage chips can only be written to a certain number of times, so the drive's controller tries to spread out the writing and erasing activity.

That's correct unless your "files" include something that can actually be sped up with fast I/O, like a ton of source code (e.g. hundreds of files) you want to compile. A modern hard drive is easily fast enough to load your average document in less than a second, so as mentioned the benefit is only obtained when you need lots of random-access I/O which doesn't normally happen with personal data.

A really great thread on this exact issue is in a sticky, So you wanna buy a SSD? Read this first.