I use the Intel X25 SLCs on our UNIX servers. People say, "Oh, they're so expensive." That's only if they do the math comparing a RAID-10 of SLCs to a RAID-10 of platters. When you compare a RAID-0 of SLCs to RAID-10 of platters, it's a whole different cost structure, especially if the CPU is not the bottleneck. With ~700 X25s running in the data center and zero failures in almost 4 years, nobody with X25s should be thinking RAID-1, 5, or 10. You're a lot more likely to have a power supply or motherboard failure. The only reason there is a discussion at all about SLCs wearing out is because they have no mechanical parts. So the logical question is, then how long do they last, and the answer is not forever. The question of how many times a platter can be written doesn't make sense to ask because a mechanical drive will fail before it ever gets there. NO mechanical drive has a prayer of outlasting an SLC. The biggest problem with SLC is density. You can pack a lot more in a small area with MLC than SLC, but MLC is just getting its legs. As far as mission critical and getting up and running fast after a failure, you can't do that with a single box anyways. VMware is where you need to be.