Windows 8 and 8.1 Forums


Determine default Disk cluster size from manufacturer

  1. #1

    Determine default Disk cluster size from manufacturer


    Hi,

    How do I determine the cluster size that is from the Manufacturer of any hard disk drive (HD or SSD or External USB HD) (not the ones I can choose when reformatting but what the company that made the hard drive had hard-coded set when they made the drive -sector size)

    -and no, I can't go to the hard drive website because some of them do not post this info.

    I would like to reformat my usb external hard drives and my internal m.2 sata card back to the default manufacturer disk cluster size (allocation unit)

    for example see pictures below..

    Click image for larger version

    Click image for larger version

    Click image for larger version

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  2. #2


    The sector size is fixed by the drive itself and cannot be changed. It is usually 512 bytes.
    The cluster size is some multiple of sector size. The default will be 4096 bytes except for very small drives under 2 GB. This can be changed but you need a good reason to do so. The default is almost always best. Hard drives themselves know nothing of cluster size which is a concept imposed by the file system. Nothing in the screenshots shows cluster size.
      My System SpecsSystem Spec

  3. #3


    Austin TX metro area
    Posts : 638
    Windows 7 Pro 64bit [MS blue-disk set]


    I might be wrong, but I thought Windows format automatically determine the defaults before one commits the formatting. I better watch this thread, I want to know too.
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  4. #4


    Quote Originally Posted by LMiller7 View Post
    The sector size is fixed by the drive itself and cannot be changed. It is usually 512 bytes.
    The cluster size is some multiple of sector size. The default will be 4096 bytes except for very small drives under 2 GB. This can be changed but you need a good reason to do so. The default is almost always best. Hard drives themselves know nothing of cluster size which is a concept imposed by the file system. Nothing in the screenshots shows cluster size.
    ok, I think I read somewhere that it may be best to set the cluster size to the hard-coded from the manufacture sector size. Now that is where I am coming from asking how do I find the default cluster size that manufacturers use when you buy a hard drive and it's shipped to you and then you start using it, but then you format it and you don't know what the original first cluster size was when you bought it..


    Ok so, if nothing in my screen shots show cluster size, that is exactly what I need to know where to get the cluster size currently on a hard drive! what Application will tell me that?

    for example, I just bought a little sata card i'm about to install into my computer, however I was going to format it, but I want to know what the cluster size of the hard drive is right now before I format it.

    hope this makes sense.
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  5. #5


    Germany/Florida
    Posts : 4,514
    Vista and Win7


    chkdsk will tell you

    Click image for larger version
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  6. #6


    Lmiller7 or anyone else interesting as well,

    please read what the poster said about 8 posts down the page.. just look for the start of this and read this post please and then you may see why and what i'm asking about.

    thanks,



    post starts like this :

    The question for Cluster size on SolidState Disks and Memory Cards, pendrives, etc... is not just as simple as use the less size allowed.

    A lot of SSD, Pendrives and memory cards has a physical block size when writting to them, so the best choice is to figure out what that value is (no way to consult it thill what i know).

    The efect is the next:
    -If Operating System writes a block of 512Bytes and the pendrive really writes blocks of 4096 bytes, it will make that 8 blocks of 512 bytes each that are written by the operating system will overwrite the same 4096 bytes 8 times because each time the pendrive hardware will overwrite 4096 bytes on each write operation

    That is just because the SolidState memories do writes by blocks, but such block size is not the same than the one used by the Operating system when formatting a parttition, etc..

    The best is to make the OS to use the same block size for formatting than the real physical block size that will use the hardware.

    Post is here :

    Best file system and allocation unit size Corsair Flash Voyager 16GB - Flash Media - Storage
      My System SpecsSystem Spec

  7. #7


    Thank you WHS, while I have you, can I ask you also to quickly look at that link I posted above and comment on if Chkdsk will tell me the Physical block size so I can set the "cluster size" the same as that!

    That actually Is probably what I should be asking. So If I understand this correctly that is my question -

    So, I'm trying to find the physical block size that hard drives use when writing period. this is set from the manufacturer! yes? so When I format, I should apparently set the cluster size to that same of the way the hard drive writes hard coded by the manufacturer as seen in the post above! right?? this is my question! ha.


    thanks everyone though so far for looking into this with me.
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  8. #8


    As shipped from the factory hard drives do not have clusters, only sectors. Hard drives have no concept of clusters, files, folders, or file systems. All these things come from an order imposed by the file system.

    Just accept the default cluster size when you format the drive.

    Not having seen what you read I cannot comment on it.
      My System SpecsSystem Spec

  9. #9


    Hi, Well thanks for the response and that actually is what I plan on doing from now on, accepting the "default" cluster size when I format, Unless I really want smaller for space reasons like 512k etc.. (for a backup only type 4-6Terabyte hard drive where I just need space and won't be using it really..)

    If you do have time at some point just quickly browse that link I posted and tell me your thoughts on the 1 post by z666zz666z it's about the 8th post down. it's not terribly long.

    Best file system and allocation unit size Corsair Flash Voyager 16GB - Flash Media - Storage
      My System SpecsSystem Spec

  10. #10


    Germany/Florida
    Posts : 4,514
    Vista and Win7


    Quote Originally Posted by brooksndun View Post
    Thank you WHS, while I have you, can I ask you also to quickly look at that link I posted above and comment on if Chkdsk will tell me the Physical block size so I can set the "cluster size" the same as that!

    That actually Is probably what I should be asking. So If I understand this correctly that is my question -

    So, I'm trying to find the physical block size that hard drives use when writing period. this is set from the manufacturer! yes? so When I format, I should apparently set the cluster size to that same of the way the hard drive writes hard coded by the manufacturer as seen in the post above! right?? this is my question! ha.


    thanks everyone though so far for looking into this with me.
    I understand that this may be a consideration for SSDs or sticks. But since the OS writes 4K blocks 80% of the time, I would not worry about that.

    That is also one reason why those wonderful read/write performance numbers you get from the measurement tools mean nothing. It is the 4k performance that counts and even a lot more the access time.
      My System SpecsSystem Spec

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Determine default Disk cluster size from manufacturer
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