SSD - as boot, apps (min spec) or scratch or...

Discussion in 'Mac Pro' started by Deepshade, Aug 22, 2010.

  1. Deepshade macrumors regular

    Joined:
    Mar 22, 2010
    #1
    Hi all

    Looking at current SSD's and they do seem to offer exceptional performance.
    Have a little spare budget after the 6-core purchase and was wondering..

    Add a (modest)
    SSD as a boot and app disk?
    SSD as a working/scratch disk?

    Now - we all would like the biggest, fastest etc etc.
    But taking another view,ie in 6 months time there are going to be cheaper, faster,bigger, better value for money. So - for design CS4/5, 3D...looking for drive big enough to make worthwhile testing the water.

    Still a bewildering amount of options out there.
    A starting point seems to be 60G OCZ vertex 2 ?
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

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    Finland
    #2
    SSD as a scratch disk isn't that good IMO because that involves a lot writing to the disk which is not good for SSD so it may wear out pretty soon. Maybe someone knows how long it would be usable at decent speed.

    I would get SSD as boot and app drive and then something like Caviar Black (maybe two in RAID 0) or VelociRaptor as scratch disk.
     
  3. Deepshade thread starter macrumors regular

    Joined:
    Mar 22, 2010
    #3
    Thanks - that's the direction I've been leaning towards (or possibly the Samsung Spinpoints)

    SSD is an emerging technology - I'm interested in testing the water - but don't have the need or budget for anything else.

    hence min spec
     
  4. ChuckBlack macrumors member

    ChuckBlack

    Joined:
    Jul 5, 2010
    #4
    Ssd

    I'd check out SSD a little more, these newer ones claim to not slow down. And my understanding is that formatting an SSD restores it anyway. An SSD for a scratch disk would be perfect in a situation where you could re-format it easily at will.

    Just from what I understand, I could be wrong...

    Here's a link to some sweet looking SSD's
    http://eshop.macsales.com/shop/internal_storage/Mercury_Extreme_SSD_Sandforce
     
  5. freedom42 macrumors newbie

    Joined:
    Aug 19, 2010
    #5
    Just formatting the drive doesn't restore its performance. A manufacture specific command has to be thrown at the drive. TRIM support is how Windows (vista or 7) maintains performance by letting the drive know what it can erase on a proactive basis. Drive manufactures have other schemes which try to do the same thing without explicit OS interaction.

    This is exactly what I'm going through right now with a product development where I'm moving to Windows 7 Embedded to get TRIM support. In my case I'm dropping frames over time where the only recourse is using a supplier utility to reset the drive (e.g. w/o trim), followed by reformatting and rebuilding the directory structure. We started down this path over a year ago where solutions were less available.

    Sandforce is something I'm also looking at as well but there are fewer suppliers that have industrial temp range SSD's with sandforce controllers.
     
  6. mattmower macrumors member

    mattmower

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    Aug 12, 2010
    Location:
    Berkshire, UK
    #6
    I've read quite a bit of what Anandtech has to say about SSD's today, principally:


    The gist seems to be that, up to the arrival of the Sandforce controller, the Intel X25-M was the best SSD on the market when you considered performance and, in particular, performance with high wear. And the performance characteristic that matters most (certainly for a boot disk) is random write latency.

    The main issue with SSD's is wear over time causing drops in the random write performance as the drive cannot write without first re-arrange content to free up blocks. With a drive like an X25-M you can use the TRIM command to recover almost 99% of the new drive performance. But Mac OS X doesn't support TRIM and Apple seem to be in no hurry to add it.

    Sandforce controllers, by design, are less susceptible to this problem of degraded write performance under high wear and so seem pretty suitable for Mac's. I think that's one of the reasons that Lloyd Chambers is so hot on the OWC SSD you linked to (the other being that it is, anyway, really quick).

    I'm kind of bummed that OWC don't have a UK reseller.

    Anyway, I hope this precis might help a little.

    Matt
     
  7. reel2reel macrumors 6502a

    reel2reel

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    Jul 24, 2009
    #7
    How does a Bootcamp installation factor into this? Is it possible to install the Mac OS only on an SSD and then Home folders and Bootcamp on a separate drive?
     
  8. Hellhammer Moderator

    Hellhammer

    Staff Member

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    Dec 10, 2008
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    Finland
    #8
    There are several other drives using the same SF-1200 controller, OCZ Vertex 2 for example. Prices are quite same as OWC drives'.

    Yes. When installing Windows, you can select what is the target of installation. As long as it's internal drive (USB or FW won't work), it will work fine. Of course you have to create NTFS partition. You can move Home folder too
     
  9. Giuly macrumors 68040

    Giuly

    #9
    Do backups to the hard drives you use along with the SSD(s), and replace them when they stop working. Even if you RAID0 4 SSDs, you only need one 1TB hard drive to backup them.
     
  10. studiox macrumors regular

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    Aug 3, 2004
    Location:
    Stockholm / Sweden
    #10
    I'd go with the Intel X25 as a Boot drive - They offer the best bucks for price/performance. 160G is a good value imho.

    You can install windows on the same drive if you want (if you want to dedicate 50/59 of it for windows/osx, 80G should be enough)

    Installing SSD in the cd bay area is a no-no (at least to my own tests) - Windows didn't recognize the drive at all (worked fine in osx) - Moving the 2.5" to the internal slots worked fine however.

    You should get an 2.5" to 3.5" adapter (like this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16817991007)
     
  11. reel2reel macrumors 6502a

    reel2reel

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    Jul 24, 2009
    #11
    Thanks a lot. Do you know if the Boot Camp assistant can be used to create the partition on another drive, or do you need to create it with Disk Utility and then point Boot Camp to the partition during the Windows installation?
     
  12. Hellhammer Moderator

    Hellhammer

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    Finland
    #12
    Not 100% sure but can't see why not. Boot Camp Assistant doesn't do more than helps you to partition the HD and restarts the computer so if it can't, then use Disk Utility
     
  13. studiox macrumors regular

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    Aug 3, 2004
    Location:
    Stockholm / Sweden
    #13
    You only need the boot camp assistant if you need to change the size of an existing disk to "fit" windows on

    If you have a new empty drive windows installation will detect it and you can format it from windows. Just be sure to remember the slots/size of it so you don't format the wrong one :) (that is normally not possible as Windows does not like to install on EFI drives but to be on the safe side)
     
  14. telco*engineer macrumors member

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    Aug 18, 2009
    #14
    I've had the X25 for almost a year and performance is still great, 15 sec bootup time ! Apps run amazing quick
     
  15. reel2reel macrumors 6502a

    reel2reel

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    Jul 24, 2009
    #15
    Okay, thanks (to Hellhammer, too) for the info.

    I'm just confused at what stage the Boot Camp drivers get installed. I'm sure I'll figure it out, though.
     
  16. Hellhammer Moderator

    Hellhammer

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    #16
    They get installed when you install them from the Snow Leopard disc or download them from Apple's site. There isn't always a need for those though, usually Windows provides all drivers you need
     
  17. reel2reel macrumors 6502a

    reel2reel

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    #17
    Excellent, thanks!
     
  18. ntrigue macrumors 68040

    ntrigue

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    Jul 30, 2007
    #18
    OWC Enterprise SSD are the best. They reserve 7-30% for junk writes. No slowdown over time.
     
  19. deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #19
    You are intertwining two different issues.

    The first issue is that the memory cells on flash drives wear out each time a cell is erased. That is they get to the point where they fail to store data correctly. The effect of that is your twofold. Minimally that the amount of storage on the drive goes down over time. (your drive gets smaller. ). Worse case you start to loose data through corruption. There is an illconcieved notion that SSD drives don't wear out. That notion was built on cases where folks were using RAM to build SSDs. Flash based SSDs do wear out pure and simple.


    Because of this first issue there is a second issue. Flash drive controllers take active measures to spread the erasures over multiple different cells. If you write to logical block address 42 six times in reality at the physical level the drive may write to six different cells for each one of those times. There are tricks were they can avoid the erasure but they don't work all the time. That issue boils down to the need for the drive to have a large pool of memory cells that it knows it can erase and reusue. With a large pool and some other tricks it can keep the write performance high over an extended period of time.

    So writes are bad for the long term health of a SSD drive. How bad depends in part how clever the controller is and how much the cells resist wearing out. Recently there have been some improvements on the wear front.

    The TRIM command is a "nice to have" but it isn't necessary in increasingly more cases were the controllers aren't anemic in parallel processing capabilities and/or "smarts". TRIM helps hide the latency between the normal read/write flow from/to the disk and doing garbage collection work (prepping cells avoiding erasing previously to being written to later. ). The TRIM command serves a two fold purpose. First it stops read/write requests from being issued ( that's right it slows down read/writes because if sending a TRIM command can't be sending a read/write command. ). The second impact is that it sends more information to the drive so its garbage collector can be applied to a broader set of cells ( so the pool of erased and prepped cells are larger. ). Most file systems don't "zero out" file blocks when file is abandoned. The are unlinked and just left with their old contents. TRIM just communicates to the disk that they have been abandoned. (note that if those cells are proactively recycled the ability to do disk recovery in a corrupted file system metadata situation is removed. )


    TRIM isn't as necessary because for every block you skip to write to another the one you just skipped can be potentially added to the free list. (e.g., remap logic address 42 to another empty/prepped ). As long as get some spare cycles to press the one just left it should be read by time its turn in the reuse list comes due. If you create a long enough "reuse later" queue it will be ready by time need another new one.


    The only place that fails is if somehow have an extremely long list of write that blow out your "reuse later" queue. For example all of a sudden need to write out a 10GB file on a 50GB disk without any reads in between at all. That just doesn't happen very often if have provisioned the SSD capacity correctly and have a smart controller.


    You can easily create a larger pool of prepped cells by just not filling up the drive to a relatively high water mark. Usually these benchmarks consist of filling the drive up till it full and showing how the drive slows down. You can avoid the latter by simply just not doing the first.

    So for example. If you require on average 50GB of scratch space your drive will do better if only fill 25% of it than if you fill 90% of it.

    The OWC drives with approx 30% over provisioning aren't going to help much if your write bursts are in the 10% range and you had alot of data squatting on the most of the memory cells keeping them occupied. Over time you would be killing off the drive faster in a very high write scratch environment.
     
  20. khollister macrumors 6502a

    khollister

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    Location:
    Orlando, FL
    #20
    So something I'm curious about is whether you should move the swap file off of the SSD OS boot volume onto a mechanical disk? I realize there isn't a huge amount of page ins/outs these days with 16-32GB of RAM, but still ...

    What is standard practice on this currently?
     
  21. Deepshade thread starter macrumors regular

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