[?] SSD provisioning

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

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  1. jeremyshaw

    jeremyshaw Big time Idiot

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    Hello,

    I've read for the SSD to do Garbage Collection effectively, it needs at least some 10% free space. To get that free space, do I need to just simply keep 10% of my partition free of files? Or do I need to actually make the partition 10% smaller?


    Thank you very much! :)
    -Jeremy
     
  2. Syberia

    Syberia Notebook Deity

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    Just keep the partition free of files. Alternately you can make the partition smaller than the actual capacity of the drive, that way even if you fill it to capacity you'll still be fine. The actual SSD controller doesn't really care about partitions.
     
  3. jeremyshaw

    jeremyshaw Big time Idiot

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    thank you :)
     
  4. tilleroftheearth

    tilleroftheearth Wisdom listens quietly...

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    No, the partition you're using needs to be 10% (or more) smaller.

    Why? Because. :p :) :D

    With the full capacity available to the O/S - all the nand can, and will be, 'dirty' at the same time and the drive can be put into a corner (performance-wise) depending on how 'real-time' the GC and/or TRIM is performed (controlled by the firmware).

    Intel and SandForce (funnily) are the only two SSD controllers that do this kind of 'real-time' GC and TRIM cleanup and will be the least likely to be put into this 'corner', but, the performance can still plummet even with these SSD's. With other SSD's which rely on idle time GC and TRIM cleanup routines - a smaller than full capacity partition will greatly enhance the ability of the drive to come out of this performance 'corner'.

    What happens when we partition the drive to anything smaller than the full capacity - we are actually limiting how many nand chips are allowed to get 'dirty' - a much different scenario than simply using 90% of the capacity as I'm sure you can see now (which allows the O/S access to all the nand chips and gets them All dirty just simply doing things like booting and shutting down Windows and not even using the system for anything else more demanding - like photo/video editing, document creation or copying/moving movies and music back and forth).

    I'm not sure where you got the 10% figure from, but in my experience even the Patriot Inferno with way over 28% over-provisioning (100GB advertised, 93GB usable and 128GB nand chips on board) simply bombed with heavy writing tasks.

    The reason we want to do GC and TRIM 'effectively' with enough over-provisioning is that it will keep the performance of the drive as high as possible (hopefully, as high as when it was brand new/first installed).

    The best way to guarantee that (in my, specific usage scenario) is to use much less than 50% of the available capacity (this is how much over-provisioning is needed for my usage to keep the drive operating at SSD speeds for me). To be more exact: with an Intel 250GB, 510 Series SSD - I'm using a 100GB formatted partition (out of 232GB available capacity).

    I'm not saying you need that much, but keep in mind that this is in addition to the 9% spare area (for the 250GB 510 version - the 120GB 510 version has 12.7% spare area by default) that my write heavy workflow requires.

    I hope you can now see that using an SSD at 70/80/90% filled is different than using it at 100% filled (or, as close to 100% filled as Windows will let you) but partitioned to the same 70/80/90% of the total capacity.

    If you're writing to the drive a lot (a LOT) and/OR you require the performance to stay as high as possible and/OR you also want the SSD to last as long as possible (at least as long as you own that system - 2-3yrs or even more): then I would consider using (much) less than a 60% partition size - even if this means that you would need to get a larger capacity SSD so that you're able to sacrifice some additional capacity for the longetivity and the sustained performance level required.

    If the above leaves you with a cross-eyed look just reading it: simply read the second paragraph or simply just the third sentence again. :)

    Hope this helped?
     
  5. jeremyshaw

    jeremyshaw Big time Idiot

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    Ah, thank you :)

    So I guess that is related to deleted files not really being "deleted," on emptying the recycle bin? I know my Vertex 2 slowed down BIG TIME after a while of useage as my laptop's only drive (m11xr2), but for some reason, my desktops C300 is still seemingly okay... (both 120/128GB), though I have not filled my C300 anywhere near over 50% yet.
     
  6. tilleroftheearth

    tilleroftheearth Wisdom listens quietly...

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    You're welcome.

    Keep in mind though that a desktop has (usually) much more time to idle than a notebook which we turn off as soon as we're finished with it.

    The greater than 50% free space is also a factor for the C300's 'feel' too. :)
     
  7. maximinimaus

    maximinimaus Notebook Evangelist

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    Hi tiller,

    can you give me an advice how can I get 10 % provisioning with my matrix RAID0 setup?
    Windows sees both volumes as 2 physical disks, 2 primary partitions.
    Should I decrease each partition after install/loading offline with a partitioning tool?
     
  8. tilleroftheearth

    tilleroftheearth Wisdom listens quietly...

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    Software RAID, correct?

    Yeah, since Windows shows each drive separately, you would need to 'shrink' each one 10% to reach your goal.

    Pay attention that the formatted capacity remaining is identical for each drive (don't know if this will make a difference here, but with RAID, matching everything, and I mean everything is never a bad idea) I would be verifying this to the nearest MB.

    If you have two partitions on each physical drive (and it seems like you do, 64GB and 174GB), then it won't matter if you decrease each partition by 5% of the total capacity of a single drive or if you decrease one partition by 10% of the total capacity of a single drive - the effect with regards to 'over-provisioning' will be identical.

    Keep in mind though that the best time to do this is when the drive is brand new and no data is written to it yet - doing it after it has been used for a while might be a case of too little, too late (depending on how hard you push your storage subsystem, how effective it's SSD toolbox is and how aggressive the GC is implemented on your specific firmware).

    Hope this helps?
     
  9. davepermen

    davepermen Notebook Nobel Laureate

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    again, ssd doesn't see the partition. just make sure you don't fill it >90%, no matter how (having smaller partitions, or just not filling it up that much, or what ever.. it doesn't matter if you have the space at the end of the partition, the start of it, in between, etc.. it can't see it).

    i personally have the full space partitioned, and just try to not fill it to the max. if i do, i just make sure i get back to below 90% asap, and then give it time to 'recover'.

    same as with hdds, actually. you don't want to fill them up to 100% and expect them to perform well. but, unlike a hdd, an ssd can clean up itself to nice performance quite well once you 'freed it from the burden'. a hdd, typically, has to be defragmented manually afterwards.
     
  10. maximinimaus

    maximinimaus Notebook Evangelist

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    tiller, thank you for the answer.
    I have 2 SSDs in Intel matrix RAID0, configured in 2 volumes(64 GB and 174 GB). This 2 volumes are also my 2 primary partitions(C: and D: ) which are split(striped) on the 2 SSDs.
    You're right, shrinking one partition should do the job, as the data is split(striped) on both SSDs. Therefore it's sufficient to shrink only the D: partition.
    It seems better to me to create and format the second partition(D: ) with only 90 % of the capacity. This avoids the risky shrinking with a partition manager or within Windows.
    Until today Samsung has no SSD toolbox(Magician) that works with a RAID setup. But it's no problem for me to "Secure Erase" the SSDs with Ubuntu if there's a performance problem with the storage subsystem.

    According to davepermen there's is no need to this overprovisioning as long as one doesn't fill the partitions to the max(assuming one formatted the partitions with the "quick" option!).
    Is this common sense? What is your opinion about it?
     
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