[?] SSD provisioning

Discussion in 'Hardware Components and Aftermarket Upgrades' started by jeremyshaw, Oct 23, 2011.

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  1. tilleroftheearth

    tilleroftheearth Wisdom listens quietly...

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    Because writing all zero's is not the same as proper GC/cleaning for each type controller and nand type.

    I do like your super* page name though. :)
     
  2. chimpanzee

    chimpanzee Notebook Virtuoso

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    Interestingly, I was joking with OCZ support staffs back when I had the Vertex 2 that I can make a SSD that is faster than their beloved SF using the above tricks, if ATTO is the only thing we care :)

    Of course, in real life, it is of little use as completely 0s or 1s sector are very rare.
     
  3. Dufus

    Dufus .

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    I'm not so sure that is that rare to have complete 0's on a sector and wouldn't it be better to have all those sectors that aren't written yet pointing to the super page to avoid media write/read, assigning media to it?

    What happens if sectors are read. Say you have a program that reads all sectors of the disk, including those outside the partition, wouldn't it be better for those sectors that haven't been written to to return zero from the super page rather than assigning media?

    When a file is deleted its sectors can be pointed back to zero without having to assign flash media on a subsequent read.

    From reading so far when reading sectors that haven't been written it seems some firmware may return indeterminate data, determinate data or determinate data using zero's. With the latter case that would seem to suggest some sort of mechanism exists for doing something similar to using a super page.

    Since the RAID0 I'm using allows for ATA commands to be passed to an individual disk of the array it should be possible to send TRIM commands and I shall look into this to see if a forced TRIM can work as it doesn't work natively. It looks a little tricky as one needs to know the mapping of the OS side to the LBA's on each disk but first need to find out how to send the correct command through the SCSI device.

    If I understand it right it seems the more free media you have the bigger the pool will be for GC to work with. With no TRIM that pool can be reduced substantially and the only way to try and keep it fairly efficient is to provide user provisioning by partitioning to use less of the disk. Of course some may find the reduced efficiency not to be a problem, YMMV.
     
  4. chimpanzee

    chimpanzee Notebook Virtuoso

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    all I can say is, theory is different from actual usage.
     
  5. jeremyshaw

    jeremyshaw Big time Idiot

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    iirc, the Corsair Performance 3 drives had an extremely overagressive GC that hampered instantanious performance, though without TRIM, mantained performance well after being "dirty."
     
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