flash vs HD

I saw a article and it talked about booting from a flash drive instead of a hd. I wanted to know whats better thou you can really go back and forth with it.

Flash read 20 mb/s write 15 mb/s
Hd i dunno like read 40mb/s and write 20mb/s

flash little seek time measured in nano secs,write ns
hd seek 5 ms,write 5.3ms

basicly you just taking the cache out of a hard drive and using that.

*most of stats used aren't made up but probly not realistic*

well, if your talking like Compact Flash cards, like you use in camera's - HD's are faster,

but if your thinking of like "flash" storage for computers, - think of ram and ram drives...

RAM and RAM drives are not flash memory, they are volatile (they lose data when they lose power). The advantages of flash storage over HDDs are lower seek times and resistance to damage from dropping and/or vibration. The disadvantages are sustained transfer rates, expense, limited size and a limited number of write cycles.

^^ i thought flash drives were supposed to be super fast and the next best thing ?

limited number of write cycles, about how many? Hd's are better and with perpendicual recording they are getting more dense which translates into more speed. Use to to drives topped out at 40mb/s and new model ones are like 50 mb/s

I think they're up to about 1 million write cycles or something, and software can spread out the load and work around bad spots. Still, not exactly soemthing you want to put your swap file/partition on. All of the problems I mentioned with flash are improving. Write cycles, speed and density are all increasing. Cost is coming down. The write speed is usually a lot slower than the read speed. Yes, flash is the up and coming thing, but it's not quite ready yet. It does offer significent power savings, though. You'll probably first see flash based HDDs in notebooks, where the low power useage and resistance to shock compared to average HDDs are most needed.

edit: Samsung is claiming burst transfer speeds faster than 4200RPM notebook drives (but slower than 5400rpm ones) in their new 32G flash notebook drive.
http://www.extremetech.com/article2/0,1558,1966644,00.asp?kc=ETRSS02129TX1K0000532

I believe flash costs something like 50x more per gigabyte than conventional HDDs.