SSD’s are the Future
Solid State Drives aren’t a new technology. What is new about them is a recent acceptance into the enterprise market. Gone are the days when SSD’s were limited to experimental or military applications. Savvy IT admins are starting to use them in laptops, desktop, and even their beloved servers. What brought about this change?
Two key elements of SSD technology had to change radically from what they were a few years ago: price and write I/O performance. We’ll discuss the latter first, for absolutely no reason at all.
Most types of solid state data storage technologies have had traditionally poor write I/O performance. The already low performance dropped even lower over time and use, as sectors became unused. Those sectors require a “wipe” to clean them of any old data before you could write new data. Since operating systems still aren’t very intelligent about where on the drive they store data, this could lead to several wipe/verify/write operations any time data needed to be written to the storage device. This coupled with the already comparatively poor write throughput when pitted against spinning magnetic media, leaves the user on a strict I/O diet. SSD’s needed to leave South Beach and head for a land that allows for larger appetites.
In the past two years, several major advances have come forth in the write I/O department. First, there is a notion of wear leveling, which uses the storage controller present in a drive to write to sectors in a somewhat equal basis. This should cause every sector to be written to a similar number of times, which extends the life of each sector. In addition, we now have on-controller garbage collection, which performs the task of searching for abandoned sectors and performing a wipe/verify cycle on the sector. Doing this in advance of the need to write to the sector reduces the number of I/O’s from 3 to 1, which has an obvious impact when compared to a storage device with no garbage collection. As well, many manufacturers are, in essence, splitting up flash memory into several independent groups and internally RAID’ing them together in a RAID0 fashion. RAID0 doesn’t take much calculation or processing power, so it is easy for the storage controller to handle this task.
Pricing for solid state storage needed to drop as well. There was a reason I mentioned military applications previously, as they were generally the only entity that could afford to use solid state storage. That’s not the case today, thankfully, as manufacturers have streamlined and refined their manufacturing process to yield more output with less input. We now see even largish storage devices (250GB and up) available for under $1,000.
What, you say? That’s too expensive still? Consider this, then. If one 250GB SSD can deliver the same I/O performance as an 8 drive RAID 10 array, does that change your tune? How about if the same SSD could outperform a 10-16 drive RAID array? What then?
Reality is that SSD performance and price have reached a point where it is no longer financially justifiable to spend money on spinning magnetic media and all of the trimmings it requires. OK, plain old hard drives are still best in the quantity department, but that’s where they are destined to retire…just a lot of dumb, slow storage that people don’t even want to touch. Sounds like a DLT tape to me.
On a more personal level, we use SSD”s in many of our workstation systems already. Our first production server to use SSD’s is going into service this summer. Plans are in place to upgrade additional servers with SSD-based storage arrays. SSD’s are the future, so get on board.