U ovom clanku nije problem u Wear leveling algoritmu (metodi), vec druga vrsta SSD "fragmentacije" koja je definirana na slijedeci nacin:
"This write combination also significantly reduces the effects of what Intel calls “Write Amplification”.
While MLC flash can be written in small pages (~4KB), it can only be erased in blocks (~512KB). Think of each flash block as a CD-RW – you can write a little at a time to it, but when it is full you must erase the whole disc and start over. If you were to write only 1KB to a previously occupied flash block, that entire block of flash (512KB) would have to be read into memory, cleared, and its contents rewritten, just to get your 1KB of data saved to it."
...
"Write combining sounds like a great idea on the surface, but things that seem too good to be true normally are, and there is no free lunch here either.
Since the flash locations are isolated from the OS by a lookup table, these fragments can not (presently) be directly manipulated by the OS, leaving any defragmentation efforts to the SSD itself. These fragmented areas will remain until they are overwritten by larger contiguous files. The end result is that the drive is not so much ‘adapting’ as it is approaching a steady state level of internal fragmentation as a result of the mix of small / large files being written to it. When we put the screws to the X25-M in the lab, we found that a ‘used’ X25-M will always perform worse than a ‘new’ one, regardless of any adaptive algorithms that may be at play. We also found that in some cases, the drive would drop to significantly below manufacturer specs."
EDIT:
Bojim se da ni SLC nije ovoga postedjen
LINK!, ali je dobra stvar sto se vec radi na rijesavanju ovog ... "problemcica".
Sto se kontrolera tice ... ako je Intelov ovakav, kakvi su onda drugi
E da, a evo i (trenutno) najjaceg SSD-a na trzistu, takodjer sa ovim "djecjim bolestima"
LINK!
Nekako mi se cini da je nastao toliki skok u performansama diskovnih flash podsustava, da su jednostavno ostali cimbenici vazni za ostvarivanje kvalitetnih performansi uhvaceni nespremni (ATA protokoli, SSD kontroleri, komunikacija i metode na liniji OS - SSD kontroler, bandwidth onboard kontrolera ...)
EDIT:
Jedna od glavnih prednosti SSD tehnologije je sposobnost multitaskinga (koji je direktno proporcionalan IOPs specifikaciji, odnosno ukupnom broju mogucih ulazno-izlaznih operacija).
Brojke u Random prometu govore slijedece:
Random Write (najzahtjevnija IOPs specifikacija):
Samsung SLC <900 IOPs
Intel X25-E <3,300 IOPs
Random Read (vrlo bitno prilikom recimo podizanje OS):
Samsung SLC <3,500 IOPs
Intel X25-E <35,000 IOPs
Brojke ne lazu, a Intelova primarna i osnovna prednost jest solidan (10-kanalni) kontroler koji koristi svoj dovoljno velik cache ... e sad uzevsi u obzir ove prije spomenute probleme koje SSD diskovi prolaze (iznimno velik i dugotrajan multitasked random promet) njihove se brojke otprilike prepolove.
Za usporedbu jedan standardni 7,200 RPM disk ima ~100 IOPs-a u Read-u/Write-u, iz cega proizlazi njegova (poznata) ogranicena sposobnost multiple read i write operacija odnosno manifestira se kroz zastajkivanje prilikom pokretanja i rada sa vise aplikacija odjednom (kao i poznato trzanje kod losijih SSD diskova).
Samo mala napomena: IOPs specifikacija je obrnuto proporcionalna sa pristupnim vremenima prilikom citanja i pisanja podataka.