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Thread: Optimized partition layout question, why is it "optimized?"

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    Optimized partition layout question, why is it "optimized?"

    I am curious why this layout is optimal. My understanding is that it moves the MFS partitions to the beginning of the disk. Isn't the ouside edge of the disk faster and if so why is it better to move the media partitions inward?

    View this post to see an example of the different layouts. Specifically look at the base address of the partitions http://archive.tivocommunity.com/tiv...531#post568531

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    Quote Originally Posted by ciper View Post
    I am curious why this layout is optimal. My understanding is that it moves the MFS partitions to the beginning of the disk. Isn't the ouside edge of the disk faster and if so why is it better to move the media partitions inward?

    View this post to see an example of the different layouts. Specifically look at the base address of the partitions http://archive.tivocommunity.com/tiv...531#post568531
    It places the root partitions, and the mfs metadata partitions, in the center of the disk, presumably to minimize the average seek time to these regions.

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    I don't know all of the details but according to the post I linked to it puts all of the Media partitions first, then the two MFS apps finally followed by partitions 1-9.

    I think we may have both been partially right though. With partitions 1-9 and the two MFS app at the end of the disk it should potentially speed reads of those up. I could see this as meaning faster booting and better database read times I guess?

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    Quote Originally Posted by ciper View Post
    Isn't the ouside edge of the disk faster and if so why is it better to move the media partitions inward?...at the end of the disk it should potentially speed reads
    What makes you think that hard drives order sectors starting at the inside cylinder?

    Older drives (Shugart ST506 interface) started numbering at the outside edge. There were things which kicked in on higher numbered (inner) cylinders, like write precompensation and reduced write current.

    It's not clear to me why a manufacturer would want change from that convention to place the first sector on the inside in a modern drive, although they could. From what I can tell, none of them do.

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    Quote Originally Posted by mike_s View Post
    What makes you think that hard drives order sectors starting at the inside cylinder?
    It's been so long I'm not really sure why I think that. The page you linked says "Since hard disks are filled from the outside in, the fastest data transfer occurs when the drive is first used."

    If that is really true then the optimized layout would put the media partitions on the first part of the disk, which happens to be the outer edge, which also should be the fastest.

    Can anyone find the original discussion of the -p option of mfstools? I'd like to see the reasoning.

  6. #6
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    Quote Originally Posted by ciper View Post
    If that is really true then the optimized layout would put the media partitions on the first part of the disk, which happens to be the outer edge, which also should be the fastest.
    No. Media partitions are moved to the edges, but not for that reason. The media partitions only have to be fast enough to keep a media stream going for playback/record. More speed than that doesn't do much.

    A speed increase is going to be most useful when running root partition applications or scripts, like tivoapp, where faster access will make a difference.

    As Tiger said about MFS Tools version 2.0:
    The partition layout of the first drive will be such that the application data will be in the middle of the drive and the video on the outside, causing the head to have to seek less.
    Jamie, as usual, is correct.

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    I must be confusing myself somehow.

    The "optimized" layout is in the order 1 13 11 2 3 4 5 6 7 8 9 10 12 meaning MFS media at the beginning, 2-9 next and the two app partitions after it. In other words MFS Media - OS - MFS App

    How is it centered if out of a 40gb HD 35gb are used by the first two partitions?
    Last edited by ciper; 12-04-2008 at 08:42 AM.

  8. #8
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    Quote Originally Posted by ciper View Post
    ...
    The "optimized" layout is in the order 1 13 11 2 3 4 5 6 7 8 9 10 12 meaning MFS media at the beginning, 2-9 next and the two app partitions after it. In other words MFS Media - OS - MFS App
    That doesn't look like the layout on a stock tivo drive. IIRC, A stock tivo drive normally has two equal sized media partitions (11 and 13) with 11 at the start of the disk and 13 and the end.

    An mfstools restore will place the two original media partitions at the start of the disk and make a new one (for expansion) at the end of the disk. Of course, this is only "optimal" if the new drive is twice the capacity of the old one. To do better than that, it would have to resize zones/partitions, something it doesn't do.

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    I know that partitions 1-9 can have the locations manually adjusted using standard tools but what about MFS app/media partitions? Is there a way for me to move the location of partitions 10-15 or are my only choices either in a straight line (non optimized) or with the media straddling the rest of the data (optimized with -p in mfsrestore or the checkbox in winmfs)?

    I wouldn't mind even starting with a fresh image if it is possible. My goal is to have both app partitions either at the beginning of the drive or at the end of the drive.
    Last edited by ciper; 08-12-2010 at 02:14 AM.

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