Zvýšil by sa výkon zápisu, ak by bol preformátovaný pevný disk vyplnený nulami?

Obsah:

Zvýšil by sa výkon zápisu, ak by bol preformátovaný pevný disk vyplnený nulami?
Zvýšil by sa výkon zápisu, ak by bol preformátovaný pevný disk vyplnený nulami?

Video: Zvýšil by sa výkon zápisu, ak by bol preformátovaný pevný disk vyplnený nulami?

Video: Zvýšil by sa výkon zápisu, ak by bol preformátovaný pevný disk vyplnený nulami?
Video: Check this Amazing Story of Recovery from Chronic Fatigue Syndrome - YouTube 2024, Marec
Anonim
Ak sa chystáte preformátovať pevný disk, existuje niečo, čo by mohlo "zlepšiť" napísať výkon neskôr, alebo je to niečo, o čom by ste sa ani nemali obávať? Dnešný príspevok SuperUser Q & A má odpovede na otázky zvedavého čitateľa.
Ak sa chystáte preformátovať pevný disk, existuje niečo, čo by mohlo "zlepšiť" napísať výkon neskôr, alebo je to niečo, o čom by ste sa ani nemali obávať? Dnešný príspevok SuperUser Q & A má odpovede na otázky zvedavého čitateľa.

Dnešná relácia otázok a odpovedí sa k nám pridelí zdvorilosťou SuperUser - podskupiny Stack Exchange, skupín webových stránok týkajúcich sa otázok a odpovedí.

Foto s láskavým dovolením Chris Bannister (Flickr).

Otázka

Čítačka SuperUser Brettetete chce vedieť, či vyplnenie pevného disku s nulami zlepší výkon zápisu:

I have a 2TB hard-drive that was 99 percent full. I have deleted the partitions with fdisk and formatted it as ext4. As far as I know, the actual data that was on the hard-drive still exists, yet the partition table was reassigned.

My question is: Would it improve the write performance for further write actions if the hard-drive was clean? By ‘clean’ I mean fill the hard-drive with zeroes? Something like:

dd if=/dev/zero of=/dev/sdx bs=1 count=4503599627370496

Bolo by vyplnenie pevného disku s nulami zlepšenie zápisu?

Odpoveď

Sponzor SuperUser Michael Kjörling má pre nás odpoveď:

No, it would not improve performance. HDDs do not work like that.

First, when you write any given data to a rotational drive, it gets transformed into magnetic domains that may actually look very different from the bit pattern you are writing. This is done in part because it is much easier to maintain synchronization when the pattern read back from the platter has a certain amount of variability. For example, a long string of ‘zero’ or ‘one’ values would make it very hard to maintain synchronization. Have you read 26,393 bits or 26,394 bits? How do you recognize the boundary between bits?

The techniques for doing this have evolved over time. For example, look up Modified Frequency Modulation, MMFM, Group Code Recording, and the more general technology of run-length limited encodings.

Second, when you write new data to a sector, the magnetic domains of the relevant portions of the platter are simply set to the desired value. This is done regardless of what the previous magnetic domain ‘was’ at that particular physical location. The platter is already spinning under the write head; first reading the current value, then writing the new value if and only if it is different. It would cause each write to require two revolutions (or an extra head for each platter), causing write latency to double or greatly increasing the complexity of the drive, in turn increasing cost.

Since the limiting factor in hard-drive sequential I/O performance is how quickly each bit passes under the read/write head, this would not even offer any benefit to the user. As an aside, the limiting factor in random I/O performance is how fast the read/write head can be positioned at the desired cylinder and then the desired sector arrives under the head. The major reason why SSDs can be so fast in random I/O workloads is that they completely eliminate both of these factors.

As pointed out by JakeGould, one reason why you might want to overwrite the drive with some fixed pattern (such as all zeroes) would be to ensure that no remnants of previously stored data can be recovered, either deliberately or accidentally. But doing so will not have any effect on the hard-drive’s performance going forward, for the reasons stated above.

Máte niečo doplniť vysvetlenie? Znížte komentáre. Chcete si prečítať viac odpovedí od iných používateľov technológie Stack Exchange? Pozrite sa na celý diskusný príspevok tu.

Odporúča: