[技術討論] 人類基因組或記憶的 file，是否該用 parity 保護？

EITCo

如果驚硬碟錯個bit會出科學怪人，不如查下每次細胞分裂會抄錯幾多bit先啦
其實正正係會出錯，先衍生出唔同個體，唔同物種，然後再物競天擇

雖然重要資料份底一定要備份同校驗，我係同意呢點

vsp

hdd每個sector有CRC

harryytm

回復 EITCo

如果 放 hdd, 之後 read出嚟有 error, 己經唔合理。因 hdd data rot 係可避免，如 snapraid, p ...
yowi 發表於 2017-7-8 20:59

硬碟上面每個Sector都有ECC，當由Platter Read咗啲Data之後，硬碟控制器(硬碟上面嗰粒CPU)會用ECC去檢查數據完整性，如果出嚟有error而又用ECC修復到就係C5，而如果重試過幾次都係讀唔到即係C6，之後會回應返個Host個Sector讀唔到。

harryytm

hdd每個sector有CRC
vsp 發表於 2017-7-8 22:26

正確，而家無一隻硬碟係會寫RAW Data落Platter上面，硬碟控制器喺寫Data落碟片之前，已經加咗ECC同Parity先至寫落Platter上面。

harryytm

回復 harryytm
then what differ from snapraid?
yowi 發表於 2017-7-8 23:52

snapraid split all the files on the disk into blocks and create parity data on these block, in case of some blocks unreadable, it can use the parity data to recover the data and write it back to the damaged part of the file.

回復 harryytm
hdd s own ecc know there is error, but cant correct it?
yowi 發表於 2017-7-8 23:52

Harddisk build-in controller do it all the time when reading/writing every disk sector, just it don't let user know about that happening.

harryytm

Every kind of "Digital Media" such as CD, DVD, BluRay, SSD, Harddisk, RAM, all are storing "Digital data" in analog form, and use checksum or ECC to make use retrieved(or read) data are without error, or do some kind of error correction when error are found.

Optical media such as CD, DVD, BluRay uses Reed–Solomon error correction to package data and then use Eight-to-fourteen modulation to modulate packaged data into analog signal, and then record analog signal onto the disc.
https://en.wikipedia.org/wiki/Re ... on_error_correction
https://en.wikipedia.org/wiki/Eight-to-fourteen_modulation

On a harddisk, all data to be written onto the disk would be added ECC data before packaged into HDD's own internal data format, and then the HDD on-board controller will modulate the packaged data into analogue signal and then use the head to write the analogue signal onto the disk platter.

XexeX

呢個應該係生物學範疇，樓主硬要套用喺「儲存燒錄」嚟討論，感覺有少少膠…

如果係，太陽都應該要有parity保護，一陣其中一支bit由0變咗1好大鑊。