Chtělo by se zvolat, že to konečně někoho napadlo. Mluvíme o SSD, které využívá krom pamětí zapisujících více bitů do jedné buňky také paměti SLC s jedním bitem na buňku. Jak se to ale v případě MiDrive liší od SLC cache?
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Diskuze k článku: Enmotus MiDrive kombinuje hlavní SLC a vedlejší QLC na jednom SSD
14.1.2020, Jan Vítek, aktualita
Protoze s tim prisli uz od WD - jejich SSDcka, resp. to snad vyvinul SanDisk - maji interne cast pameti jako SLC pro zapis a pak, kdyz je cas, to prepisuje do TLC bunek _na tom samem pametovem cipu_. Cili - to jsem pochopil z prezentace od WD - ten nadrizeny kontroler jen rekne, ktery blok zapsany jako SLC se ma na tom samem cipu prekopirovat do TLC bloku. Coz mi prijde super cool - treba 1TB disk by mel mit asi az 12GB tohoto SSD vyhrazen jako SLC cache. Proto by mely disky od WD/SanDisku byt rychle pri instalaci treba widli - protoze cela instalace bezi do SLC sekce celeho disku. A ty SSD disky nejsou tak drahe. Nevim ale, jestli je delaji v jinem form factoru nez SATA, snad ano. Pri instalaci OS zaroven dochazi k prepisu teto SLC cache do TLC pameti, takze se disk pri cele instalaci chova docela svizne, prestoze nema DRAM buffer.
Neco jsem nasel tady
https://www.anandtech.com/show/14223/the-western-digital-wd-blue-sn500-ssd-review/2
ale nepamatuji se jiz kde presne. Mozna zde
https://www.anandtech.com/show/13760/the-western-digital-wd-black-sn750-ssd-review/2
The WD Black SN750's behavior during a full drive write is quite similar to that of its predecessor, albeit with a 5% improvement in write speed after the SLC cache fills up. The cache fills after about 12GB of writes, but since performance after the drop is steady at around 1.5GB/s the small cache isn't really a problem.
Neco jsem nasel tady
https://www.anandtech.com/show/14223/the-western-digital-wd-blue-sn500-ssd-review/2
ale nepamatuji se jiz kde presne. Mozna zde
https://www.anandtech.com/show/13760/the-western-digital-wd-black-sn750-ssd-review/2
The WD Black SN750's behavior during a full drive write is quite similar to that of its predecessor, albeit with a 5% improvement in write speed after the SLC cache fills up. The cache fills after about 12GB of writes, but since performance after the drop is steady at around 1.5GB/s the small cache isn't really a problem.
Odpovědět0 0
https://documents.westerndigital.com/content/dam/doc-library/en_us/assets/public/western-digital/product/internal-drives/wd-blue-ssd/user-manual-wd-blue-3d-nand-sata-ssd.pdf
Tiered Caching
The WD Blue 3D NAND SATA SSD uses a tiered caching structure to improve write
performance and endurance.
Modern operating systems typically access the storage device using small access
blocks; the majority of these being 4KB. These access blocks are incongruent with
the physical block size (less than 1MB) of the newer generation of
flash
memory
technology, and writing directly to the TLC array is also slower than writing to SLC
blocks. To overcome these hurdles, the WD Blue 3D NAND SATA SSD employs three
storage layers:
▪ Volatile cache — DDR DRAM cache
▪ Tiered Caching structure — A non-volatile
flash
write cache
▪ Mass storage — TLC NAND
flash
The tiered caching structure is a pool of X1 blocks which are used as write cache to
accumulate and consolidate all writes at high speed. It works in the background,
then
flushes
them into the larger X3 storage blocks and uses optimized write
transaction sizes to maximize endurance.
All host data is written to X1 blocks to achieve the highest performance. Three X1
blocks are copied sequentially into one X3 block during the
flush
to mass storage
when exceeding their threshold.
Tiered Caching
The WD Blue 3D NAND SATA SSD uses a tiered caching structure to improve write
performance and endurance.
Modern operating systems typically access the storage device using small access
blocks; the majority of these being 4KB. These access blocks are incongruent with
the physical block size (less than 1MB) of the newer generation of
flash
memory
technology, and writing directly to the TLC array is also slower than writing to SLC
blocks. To overcome these hurdles, the WD Blue 3D NAND SATA SSD employs three
storage layers:
▪ Volatile cache — DDR DRAM cache
▪ Tiered Caching structure — A non-volatile
flash
write cache
▪ Mass storage — TLC NAND
flash
The tiered caching structure is a pool of X1 blocks which are used as write cache to
accumulate and consolidate all writes at high speed. It works in the background,
then
flushes
them into the larger X3 storage blocks and uses optimized write
transaction sizes to maximize endurance.
All host data is written to X1 blocks to achieve the highest performance. Three X1
blocks are copied sequentially into one X3 block during the
flush
to mass storage
when exceeding their threshold.
Odpovědět0 0
Konečně to nekoho napadlo dat na ssd SLC a podle vlastniho uvazeni ho cast prepnout na QLC
Ja mám stale na C: mene nez 200GB, takže bych ani z SLC neprepinal a vyuzival jeho max rychlost
Snad se toho chytne více vyrobcu, myslim ze vsichni zakaznici nechteji jit cestou vysokokapacitnich SSD s QLC nebo snad i PLC nebo co je potom
Ja mám stale na C: mene nez 200GB, takže bych ani z SLC neprepinal a vyuzival jeho max rychlost
Snad se toho chytne více vyrobcu, myslim ze vsichni zakaznici nechteji jit cestou vysokokapacitnich SSD s QLC nebo snad i PLC nebo co je potom
Odpovědět0 0
Stejně člověk mívá ssd na systém a podstatně pomalejší hdd na "chladnější" data. Nápad, mít to na jedné m2 kartě vypadá docela zajímavě.
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