SSD + scratch disc

Discussion in 'Mac Pro' started by bobbydaz, Sep 19, 2010.

  1. bobbydaz macrumors regular

    Jan 24, 2009
    Looking to put a 120 SSD in my Mac pro as a boot drive but not sure how best to set up along side my HDDs. This was my planned config, but open to advice:

    SSD - system + apps

    2x 1tb set up as 2tb RAID 0 - work files + home folder

    1tb - Time Machine

    This leaves one bay spare, but where would be the best place for my scratch disc, on the SSD? If so would a partition be the best option? Working in graphic design, mainly in Photoshop so performance is my main priority.

    Another thing to throw in the mix is what performance increase could I expect by replacing the HDD RAID with an SSD for my files, would this speed up open and save times?
  2. alust2013 macrumors 601


    Feb 6, 2010
    On the fence
    Not entirely sure about the scratch disk, but just a thought, you may not want to make your time machine disk smaller than the total space of your hard disks.
  3. bobbydaz thread starter macrumors regular

    Jan 24, 2009
    Good point, although the actual total size of my work folder very rarely gets over 150Gb at any one time as work is archived once completed.
  4. Demigod Mac macrumors 6502a

    Apr 25, 2008
    I'm also wondering about this: if being a scratch disk would accelerate an SSD's degradation much faster.

    Mine is an OWC Mercury Extreme.
  5. nanofrog macrumors G4

    May 6, 2008
    I wouldn't recommend placing the scratch data on the SSD, and it would be even worse if you make a partition (has to do with write amplification).

    If you want to use an SSD for scratch, I'd go with the 40GB SSD from OWC, as it's fast and cheap (real world results have shown up = 225MB/s sustained transfers; currently listed for $110). Just be prepared to toss it in 1 - 1.5 years. BTW, this is a recent development, as prior to this disk, SSD's were too expensive to really be considered a viable solution for scratch at all.

    If you can't deal with tossing it that rapidly, then go with a mechanical stripe set (place the 1TB Time Machine disk externally to obtain the HDD bays needed). You could partition it to say 10 - 20% to keep it on the outermost tracks to improve the performance (called short stroke partitioning).

    If you're interested in further detail, search the forum (try "Areca" and "wear leveling", and look for threads in the last 3 months or so). There's a lot of RAID card information, but the write amplification issues are covered.

    Hope this helps, and good luck. :)
  6. Honumaui macrumors 6502a

    Apr 18, 2008
    ditto the TIme Machine size ;)
    I am one of those doing the real world testing :)

    do a search with my name and use the word "Efficiency"
    not sure how much you know about checking photoshop efficiency as you work ? but that should lead you to some help :)

    I am hoping the SSD last longer than what Nanofrog said ? but if they dont warranty :)
    I bought 5 SSD to test to get the best results out of LR and PS
    these two programs are my living so its important to get the performance that pays off

    the other thing for PS is snow leopard and CS5 and lots of memory if you are on leopard and CS4 or lower and have 8 or less gigs you are hurting yourself :)

    doing some testing with 300 meg files I get about 18 gigs used all the time and that is off a fresh boot with nothing else going on

    so to me 24 gigs is the new sweet spot I think if your files are about 100 megs you can get by with 16 gig memory ? but more is not going to hurt you in performance :)

    DO SSD HELP PS SCRATCH that is the big question :) YES they help a lot and for me worth it ;)

    if you work in LR putting the cache on the SSD also helps out quite a bit
    I should post my findings on LR here ;)
  7. VirtualRain macrumors 603


    Aug 1, 2008
    Vancouver, BC
    I run scratch on my SSD's but I'm not making a living off my machine where the scratch is constantly being bombarded 8 hours a day. If you are bombarding your scratch volume constantly, I agree with Nanofrog... either get a disposable SSD for scratch or use your mechanical drives. If you are just a casual user and seek the ultimate performance, run your scratch on your existing SSD.
  8. Honumaui macrumors 6502a

    Apr 18, 2008
    ya know good point :) someone like me who is on it all day long can afford to throw it away $120 for speed is nothing ?

    fun users who just want the bump and are not on it all day :) chances are it will last anyway :)

    also I still say in two years I am most likely going to want to update :)
  9. covrc macrumors member

    Jan 20, 2010

    Hi Guys,

    So I have a new OCZ Vertex 120GB SSD arriving this week.

    I will be placing it in my #2 optical bay of my Mac Pro 2009 Quad Core and using it as a boot disc.
    Should I use it also as my scratch disc for my Photoshop/Lightroom usage?

    Bay#1 WD Caviar Blue 640GB came with machine and is currently boot drive.
    Bay#2 Samsung Spinpoint F3 1TB
    Bay#3 Caviar Black 2TB
    Bay#4 Caviar Black 2TB

    Also have WD Elements 1TB external available.

    Where should I put my backup boot drive?
    What disc do I use for Time Machine?

    Is there anything I should buy to make functionality better?

    Thanks covrc
  10. nanofrog macrumors G4

    May 6, 2008
    To me, it would depend on the available capacity. If it's near full, I'd skip using the SSD, as the write amplification is high, as there's not many available cells available for wear leveling. Because of the write amplification issue, I'm hesitant about making partitions as well (better to just make a folder on the single volume IMO, as it would allow for more cells to be rotated through).

    But if there's sufficient capacity, it may be fine for causual use. It's just hard to predict the impact on lifespan when used this way, as there's no long term real world data available.

    Are you a professional or hobbyist?

    I ask, as if you're heavy on scratch, you can benefit most from a memory upgrade, then think about using either an SSD or mechanical array (you want to eliminate the need for it to begin with as much as possible).

    Honumaui can help you with figuring out how to check your efficiency % for CS5, and go from there on RAM (just ask nicely ;)). Once you get that dialed in, you can consider some form of RAID and/or SSD implementation for speeding up your system for the software you're using.

    I ask, as you're better off using 2x identical drives if you need to go with a stripe set, and 2x 2TB disks is a tad expensive to use for scratch when the primary data disks aren't as large or fast.
  11. Honumaui macrumors 6502a

    Apr 18, 2008
    I know some use the scratch also on the boot ? I dont like this at all so I would say from a PS issue ? not to do this ?

    from a LR issue I found it not nearly as fast as a dedicated cache drive

    LR uses cache to get some info going
    in Library mode the 1:1 are used in develop mode the standard previews are used and in develop mode it uses the cache to start the creation of the final image you see so cache helps it quite a bit

    but on the OS it was about half way in-between a dedicated HDD partition and a dedicated scratch ? so I would say its better than a regular HDD but not as good as a dedicated ? so your call but again I would not I like to leave my boot alone ;) and give it some room etc..

    I would for LR get a $110 or whatever they are 40 gig OWC and use that ?

    what are those discs being used for now ?
    how much storage do you need ?
    how big are your PS files usually ?
    how much ram do you have ?

    you can check the efficiency of PS google it or search for efficiency under my name ? I have described it before :)
    but that will help you out quite a bit know if you need a fast scratch or more memory etc..

    I will say LR really really really benefits from a dedicated SSD and for $110 to get a big boost might be worth it ? if you work in develop mode and hate that white slider wait !
    on my older mac 3,1 my times for the sliders to go white went from about .75 to .5 while that does not seem like much it really ads up when going through a bunch of images my new machine I am getting times of about .25 for white sliders ;)
  12. covrc macrumors member

    Jan 20, 2010
    So Many Questions

    I think my PS Effiency is 65%

    I currently have only 6GB RAM 2Gx2Gx1Gx1G.
    Can I add two 4GB sticks and use the Two 2GB I already have?
    If not, I guess I will break down and get 4GBx3 for 12GB total.

    Is using the SSD as my Boot Drive and my Caviar Blue as my scratch disc the way to go?


  13. Sean Dempsey macrumors 68000

    Sean Dempsey

    Aug 7, 2006

    From what I've read, if you completely filled and re-wrote your SSD every day, it would take 51 years to wear out.

    Don't be afraid of wearing out an SSD! In a year, prices will have halved, capacities doubled, and you'll far far far underuse your SSD as is.

    I say, do whatever. I have a 60gb OCW SSD, and my system takes up 23gigs. I set photoshop to use it as a scratch disk, and why not? It's nothing that can't be easily fixed.

    Hard drives are NOT long term investments. They're bic disposable lighters. Use the hell out of them, and always have a redundant backup, and a little cash in case you break one. Problem solved.
  14. nanofrog macrumors G4

    May 6, 2008
    You'd need to use all 4GB UDIMM's, as they don't play well with 1 or 2GB capacity UDIMM's (and cannot be mixed with non ECC or RDIMM versions).

    As per the disks, I'd say Yes.

    The specification data is based on empty disks = entire disk is available for wear leveling (not real world usage which means capacity that would sit used, such as an OS and applications reducing the available capacity for wear leveling), and on the best 90% of the cells.

    You can consider ~$100 per disk disposable, but there's few SSD's that you'd want in that range. Fortunately, the recent 40GB model from OWC fits the bill so long as a user is willing to dispose of a drive on a 1 - 1.5yr cycle.

    But the larger SSD users tend to want/use for OS/applications disks, not so much for professional users, given the cost is still high. The occasional hobbyist OTOH, could get away with it.

    It depends on budget and usage right now, as SSD's are still high in cost/GB, meaning they're not as disposable as mechanical disks for most users yet.
  15. Honumaui macrumors 6502a

    Apr 18, 2008
    I would say get 2 4 gig sticks ? if funds are tight ? if you can swing 2 8GB sticks ? go that route ? this will allow you to go more later if you want and you still have 16 as base !!!

    as the scratch ? I would say point it to the fastest HDD you have that is not in use when you are using PS !!! so if the blue is sitting their ? I say try it out
    download the test at and test :)

    just note that with just 37 gigs left if you ever work on HUGE files you can fill that scratch pretty easy ! and you will choke your OS to a crawl !
    simple restart PS or purge eveything on scratch ? but just note that it can happen

    in testing if I wanted to use SSD I did fill up the 40 gig once !!!!

    also make sure you have a second scratch pointed to !!!

    as said the scratch as your boot was not as fast in my tests as a dedicated ? I also hate things using my OS if it wants to page when it needs to I would rather keep it free and breathing room to do what it wants

    my thoughts are if 40 gigs is not enough ? you are working on some huge files and things are going to be slow anyway ? so the first 40 keeps things fast for most uses

    I am not saying dont do it :) just saying their are some other things to think about :)

    also with my testing of discs in many configurations my final outcome is now
    2 40 gig SSD set for my LR cache and share with my PS scratch if I have a big PS job I just purge my LR cache before hand so I have the full 80 gigs

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