- Flash-based SSDs have a tendency to be slow to write to (in comparision to DRAM and standard hard drives)
Not correct. I mentioned this earlier. The Intel and Indilinx drives I mentioned (those would be the X25, Vertex, Falcon, Torqx, Agility, or a few others) are much faster than HDDs in terms of both read AND write performance. The X25 in particular has write performance utterly unlike anything a hard drive can do, which is why people are so interested in it. Here, look. This chart compares the performance of several high-quality SSDs against the WD Raptor. It looks at "4KB random writes," which are the most strenuous kind of IO (for both HDDs and SSDs) allowed under most filesystems:
(direct link)At the bottom of the chart is a flash drive with a non-Indilinx and non-Intel controller. Just above that,
second from the bottom, is the world's fastest consumer hard drive. The Indilinx drives are all several times faster, and then the Intel drives are multiple times faster than
that.
- Flash-based SSDs have a fairly limited number of read/writes in many cases
Reads are unlimited. Only erase cycles are limited. The X25 has a number of engineering features related to this, but the short of it is that it will last AT LEAST 10,000 write cycles per sector, which works out to around
30 years longevity assuming you write 80GB to it every day (and you bought the 80GB model). And since the drive fails on ERASE, chances are that when the drive finally becomes unwritable, you'll still have a very fast read-only copy of your data.
(More on the longevity issue: there is a feature on the X25 called "write endurance protection" which will give you a good balance of speed and performance if you are writing more than 300GB or so per day, but almost no one does that. There's is also another drive called the X-25 E, which uses SLC flash and has something like 10-20 times the write endurance. You're advised to use that one on a high-write server, but even if you do throw your X-25 M into completely the wrong job, and it fails within five years, you get another one free from Intel.)
- Cost per gigabyte in comparison to standard hard drives is significatly higher
But cost per overall performance gain is better with SSDs than with any other upgrade you can make to most computers. So if you're looking for the most cost-effective way to make a computer faster, the best way to do that is to spend a ludicrous amount of money per GB.
