A few weeks ago I replaced two Crucial RealSSD 256GB drives that were set up in a RAID 0 array, with two Crucial MX200 1TB drives also set up in a RAID 0 array in the same Dell Precision M6500 laptop. When the Crucial RealSSD 256GB drives were purchased in July 2010, the two drives offered a nominal 512GB total capacity and had a total cost of about $1240. For comparison, the two Crucial MX200 1TB drives were purchased in early November 2015, offered a nominal 2TB (1.81TB actual) total capacity and had a total cost of about $614 (eight times the storage space at half the cost five years later).The Crucial RealSSD drives in the laptop were reliable for more than five years, although roughly twice a year one of the drives would wake up slowly when powered on, causing the RAID controller in the laptop to report that the RAID 0 array was offline/damaged (along with everything stored on the laptop) – fortunately, a quick trip into the laptop’s RAID controller configuration, followed by a quick reboot fixed the hair raising problem 10+ times with no data loss. I have also seen a similar problem with an individual Crucial SSD purchased in 2011 (might be a RealSSD) installed in a Dell Precision tower, and the same fix has always worked on that computer. (The Crucial M4 256GB drives include a firmware bug that causes the computer to automatically reboot once an hour after the SSD drive has been powered up a total of 5,200 hours – that problem affected two computers that I maintain, and fortunately did not affect the Crucial RealSSD drives). I have had random lockups with the Crucial RealSSD drives in the laptop pretty much since the laptop was new, but could not say for certain whether or not the problem was caused by the Crucial SSD drives (although after restarting the computer following two of the lock ups one of the SSD drives had a slow start up, causing the RAID 0 array be be temporarily broken).After more than five years, and with just 70GB of total free space left, the Crucial RealSSD drives in RAID 0 were still able to max out both of the SATA 2 ports in read tests (read and write performance numbers were nearly identical to what was measured 4.5 years ago), and in some benchmark tests surprisingly outpaced the two Crucial MX200 1TB drives.A quick summary of the benchmark results from a Dell Precision M6500 laptop with a Core i7 X940 CPU with the SSD drives in RAID 0 using a 128KB stripe size on SATA 2 ports (SATA 3 ports are rated at 6Gbps (750MB/s) while SATA 2 ports are rated at 3Gbps (375MB/s), so a newer computer might achieve similar throughput numbers with a single SSD drive):ATTO Disk Benchmark Software:RealSSD 512 byte: 10.57 MB/s write, 64.21 MB/s readRealSSD 8KB: 101.28 MB/s write, 522.98 MB/s readRealSSD 1MB: 417.99 MB/s write, 556.44 MB/s read--MX200 512 byte: 12.19 MB/s write, 60.13 MB/s readMX200 8KB: 107.00 MB/s write, 502.75 MB/s readMX200 1MB: 517.81 MB/s write, 547.40 MB/s read--------AS SSD Benchmark Software:RealSSD 4K: 16.59 MB/s write, 12.86 MB/s readRealSSD Seq: 311.71 MB/s write (112.09 MB/s in recent benchmark version), 528.74 MB/s readRealSSD Access Time: 0.442 ms write, 0.293 ms read--MX200 4K: 15.88 MB/s write, 11.11 MB/s readMX200 Seq: 492.82 MB/s write, 535.16 MB/s readMX200 Access Time: 0.230 ms write, 0.254 ms readBoth the RealSSD and MX200 RAID arrays reached maximum performance in the ATTO Disk Benchmark starting at the 128KB write size (which probably not coincidentally is also the RAID array stripe size), and both of the RAID arrays occasionally experienced unexpected dips in the read performance in the 16KB, 32KB, and 64KB read tests. If nothing else, the benchmark tests confirm that Crucial has significantly improved the write performance of the SSD drives that it manufactures, although write performance of small files is still must slower than I would have anticipated.If you currently have a Crucial SSD drive that is at least 256GB of capacity connected to a computer that only has SATA 2 ports, that Crucial SSD drive is probably already capable of exceeding the maximum read speed through the SATA 2 ports, so you probably will not see much of a performance improvement by replacing the old drive with an MX200, unless the old drive is nearly full. In such a case, if your computer supports RAID 0, setting up a RAID 0 array with two lower capacity MX200 drives (rather than one MX200 SSD with twice the capacity) could double the read and write performance of the computer. If your computer currently has a four year old SSD drive, and has SATA 3 ports, you will likely be impressed with the performance of the MX200. If your computer currently has a 5400 RPM hard drive and SATA 3 ports, hold on tight the first time you boot the computer or launch a program – the difference is simply amazing – potentially 10 times faster for most tasks, with random IO completing roughly 52 times faster.While the Crucial SSD drives shipped with a license for a free copy of Acronis True Image HD 2014, I decided instead to copy the entire contents of the old RAID 0 array to a NAS (network attached storage) device, install the new SSD drives, and then reinstall the operating system and all software, rather than see if Acronis could transfer the contents of a RAID 0 array to a second RAID 0 array in a laptop with only two SATA 2 ports. The clean install approach generally results in the best performance, and eliminates the chance that software damage caused by a previous virus infection will be carried forward to the new SSD drives. On the Precision M6500 it is mandatory to load the hard drive drivers at the start of the Windows 7 installation, otherwise the installation will complete, but it will be impossible to log into the computer. I have successfully and unsuccessfully used the free Western Digital branded version of Acronis to clone drives – that software could not clone a 256GB Crucial SSD drive to a Western Digital 500GB Blue Drive – it is free bonus third party software, so I would not considered rating a Western Digital drive lower because some free software did not work as well as it should.Overall, I am satisfied with the performance of the MX200 SSD drives in the laptop. In the last three weeks the computer has had a single hard lockup, which appeared to be caused by the NVidia video driver.