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Exploring Advanced Format Hard Drive Technology

Posted by ScuttleMonkey on from the lift-the-hood-once-in-a-while dept.

MojoKid writes "Hard drive capacities are sometimes broken down by the number of platters and the size of each. The first 1TB drives, for example, used five 200GB platters; current-generation 1TB drives use two 500GB platters. These values, however, only refer to the accessible storage capacity, not the total size of the platter itself. Invisible to the end-user, additional capacity is used to store positional information and for ECC. The latest Advanced Format hard drive technology changes a hard drive's sector size from 512 bytes to 4096 bytes. This allows the ECC data to be stored more efficiently. Advanced Format drives emulate a 512 byte sector size, to keep backwards compatibility intact, by mapping eight logical 512 byte sectors to a single physical sector. Unfortunately, this creates a problem for Windows XP users. The good news is, Western Digital has already solved the problem and HotHardware offers some insight into the technology and how it performs."

5 of 165 comments (clear)

  1. Re:What About Linux Systems? by marcansoft · · Score: 5, Informative

    If Advanced Format drives were true 4k drives (i.e. they didn't lie to the OS and claim they were 512 byte drives), they'd work great on Linux (and not at all on XP). Since they lie, Linux tools will have to be updated to assume the drive lies and default to 4k alignment. Anyway, you can already use manual/advanced settings in most Linux parititioning tools to manually work around the issue.

  2. Re:1 byte = 10 bits? by marcansoft · · Score: 3, Informative

    No, that's totally wrong. The drive may well use 10 magnetic "cells" to store a byte (e.g. with 8b10b modulation or something similar), but that's an implementation detail. As far as everything else is concerned, bytes are 8 bits.

  3. And for an overview that knows how to do math... by JorDan+Clock · · Score: 5, Informative

    Anandtech has a much better write up on this technology, complete with correct conversions from bits to bytes, knowledge of the difference between 4096 bytes and 4096 kilobytes, and no in-text ads.

  4. Re:Large sector size good? by jabuzz · · Score: 3, Informative

    IBM's GPFS is one, though it ain't free it does support Linux and Windows both mounting the same file system at the same time. They reckon the optimum block size for the file system is 1MB. I am not convinced of that myself, but always give my GPFS file systems 1MB block sizes.

    Then there is XFS that for small files will put the data in with the metadata to save space. However unless you have millions of files forget about it. With modern drive sizes the loss of space is not important. If you have millions of files stop using the file system as a database.

  5. Re:512x4=4MB?? by the_one(2) · · Score: 4, Informative

    It was never KB and never will be. kB perhaps but not KB.