operating-system,disk , How does the OS decide data that goes in each page?


How does the OS decide data that goes in each page?

Question:

Tag: operating-system,disk

I have a comma separated data file, lets assume each record is of fixed length. How does the OS(Linux) determine, which data parts are kept in one page in the hard disk?

Does it simply look at the file, organize the records one after the other(sequentially) in one page? Is it possible to programmatically set this or does the OS take care of it automatically?


Answer:

Your question is quite general - you didn't specify which OS or filesystem - so the answer will be too.

Generally speaking the OS does not examine the data being written to a file. It simply writes the data to enough disk sectors to contain the data. If the sector size is 4K, then bytes 0-4095 are written to the first sector, bytes 4096-8191 are written to the second sector, etc. The OS does this automatically.

Very few programs wish to manage their disk sector allocation. One exception is high performance database management systems, which often implement their own filesystem in order have low level control of the file data to sector mapping.


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