I don't think they are worth the cost, really. Solid state disks are awfully expensive. White Paper Adaptive SSD Chapter 11 Solid state disks are now on the market. These disks use non-volatile memory, either flash RAM or battery backed RAM, but use a SCSI or other disk interface, so they appear to the system to be ordinary disks. There are no moving parts, so they are unlikely ever to break, unlike ordinary disks.
Access time is thousands of times faster than that of a rotating physical disk.
Another disadvantage is that system RAM is faster than solid state disks, so if you have money to spend, you'll get more performance from spending it on system memory. Still, if you have filled your webserver to its maximum with memory, a solid state disk could be more cost effective than upgrading the web server machine itself. Companies today rely on them as never before, to track and virtually to run their operations. Databases are at the heart of decision-support systems, and essential to quick response in customer support and OLTP activities. The so-called data warehouse is, after all, a database too.