Ssd

[THX]

If the device fills up with data, that list of free blocks can get quite short, making it difficult to deal with writes and compromising the wear leveling algorithm. This problem is compounded by the fact that the low-level device does not really know which blocks contain useful data. You may have deleted the several hundred pieces of spam backscatter from your mailbox this morning, but the flash mapping layer has no way of knowing that, so it carefully preserves that data while scrambling for free blocks to accommodate today's backscatter. It would be nice if the filesystem layer, which knows when the contents of files are no longer wanted, could communicate this information to the storage layer.

Ano, problem se mirne oddali pouzitim dodatecne kapacity, ale neni to ani zdaleka totez, jako kdyby WL mohl vyuzivat celou kapacitu disku.

...If the device fills up with data - k tomu nikdy nedojde. Stale bude na disku nejake volne miesto, prave vdaka tej kapacite navyse. A vzdy ked sa zapise do tohto dalsieho volneho miesta, tak sa uvolni ta stranka kde sa malo povodne zapisat, teda aj ak bude disk 100% plny, tak stale tam bude aspon ta minimalna rezerva volneho miesta aby mohol fungovat wear leveling.

AD. ta TRIM security issues prezentacia: staci ze firmware si pamata bloky, ktore su TRIM-nute a pri ich citani vrati stale blok nul.