> > assuming honest mtbf numbers, one would expect similar > > ures for the same io workload on the same size data set > > as mechanical disks. since flash drives are much smaller, > > there would obviously be fewer ures per drive. but needing > > 10x more drives, the mtbf would be worse per byte of storage > > than enterprise sata drives. so you'd see more overall failures. > > this depends on usage, obviously. i think it misses the point that > there's plenty of applications where the smaller storage (assuming a > single unit) is perfectly adequate. i swapped out the HD in my laptop > for a SD drive: the reduction in size is entirely workable, and the > other benefits make the trade a big win. there're plenty of > applications where i need relatively little raw storage: laptops, boot > media for network terminals, embedded things. > > for large-scale storage, your analysis is much more appropriate. my > file server remains based on spinning magnetic disks, and i expect > that's likely to be the case for a long time.
on the other hand, since the ure rate is the same for a mechanical disk as for your flash drive, one can't claim that it's "more reliable". it will return an unreadable error just as often. limiting your dataset on a mechanical hard drive would accomplish the same goal for less cash. and the afr (dirty secret: the mtbf number is actually the extrapolated afr^-1) is only 0.4% instead of 0.7%. at that rate, something else is more likey to eat your laptop (gartner sez 20%/year. but that's for the intel enterprise ssd, which costs more than most laptops. this article claims that flash is currently less reliable the old-fashoned disks: http://www.pcworld.com/article/143558/laptop_flash_drives_hit_by_high_failure_rates.html surprising, no? there are still plenty of reasons to want an ssd. it just seems that reliablity isn't one of those reasons yet. - erik
