SSD RAID0 as boot/app partition - advantage?

Discussion in 'Mac Pro' started by funkahdafi, Apr 23, 2009.

  1. funkahdafi macrumors 6502

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    #1
    Hi,

    I was wondering if I can expect any advantages from putting two SSDs into a (software) RAID0 array versus running a single or JBOD non-striped SSD set. Usage scenario: boot/app partition, storage for aperture work library.

    I know I will gain improvements in sequential read/write performance when using RAID-0, but will it also enhance random read/write?

    Also, is there any experience with the OCZ Vertex on this forum? Regarding to a very detailed recent Anandtech review, they are supposed to almost match the Intel X25-M performance (faster sequential performance, almost the same random performance).

    Thanks
     
  2. akm3 macrumors 68020

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    Nov 15, 2007
    #2
    Since both of those drives are an order of magnitude faster than 'old' style hard drives, why even bother putting them into a RAID? They are already 10x faster than the fastest disk based drives put into a RAID, isn't that fast enough?
     
  3. VirtualRain macrumors 603

    VirtualRain

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    Vancouver, BC
    #3
    LOL... there's no such thing as "fast enough" :p

    I say put them in RAID... you are asking the right question... why not? For which there is no good answer! :D
     
  4. pprior macrumors 65816

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    Aug 1, 2007
    #4
    Fast enough??!!

    BURN THE WITCH! BURRRRN HERRRRRR!!!!!

    Ahem....


    one problem with raid-0 sets on spinning iron is latency can be confounded with benefits in sustained writes/reads. With the SSD advantage of miniscule latency, RAID-0 is ideal. Go for it.
     
  5. QuantumLo0p macrumors 6502a

    QuantumLo0p

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    #5
    Software raid0 will only yield a small performance gain versus hardware raid. Not sure, about 15% ? Probably not worth setting up two or more X25's.

    FYI, there is a recent MR thread concerning Intel's new firmware patch that addresses the X25's performance degradation issues. Supposedly it works much better but beware of some older X25 drives as some cannot benefit from the new firmware.

    I checked into ram drives which can spank the X25 but the SSD is nipping at the heels of the hardware ram drives and are definitely are less potential trouble than ram drives.
     
  6. funkahdafi thread starter macrumors 6502

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    #6
    The question is: Will I really see any benefits on an OS boot/app drive? Where you usually have a lot of random reads and writes. The benefit of RAID0 is higher sequential read/write throughput, but as far as I know, it degrades latency and access times. Not ideal for OS/apps.

    I am currently having three 1 TB 7200 drived striped in a software raid 0 and I get great performance when it comes to large reads/writes. I get almost 300 MB/sek here. Since a single OCZ Vertex also gets around 250 MB read, I guess I will see something like 500 MB if I stripe two of those.

    However, what happens to latency and access times? Will they be doubled or degraded, or will they see an improvement through RAID0 as well?

    I am primarily getting SSD for the latency and random read/write speeds, so the least thing I want to do is sacrifice that advantage by "bottlenecking" it via RAID0.
     
  7. aibo macrumors 6502

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    #7
    I'd say go with a single X25-M. If you feel like it isn't fast enough (you won't) then you can always go for the RAID. It's hard to imagine needing anything faster than a single X25-M, since all operations become almost instantaneous.

    link... or are you just making that up? the pcperspective.com review said it fixed all issues they had with their original drive. the only thing i can think of is that the firmware update doesn't address the boot camp issue for early X25-M drives.
     
  8. funkahdafi thread starter macrumors 6502

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    #8
    That's what I thought. However, I absolutely need two drives because a single one is too small. So it's gonna be two X25-M 160 Gig or maybe the OCZ Vertex (I am still undecided) and they will be merged by JBOD or RAID0.

    So the real question still remains: Will I see the same kind of latency degradation in an SSD raid0 array that I have in a legacy hard drive raid0 array?

    Or will it not be affected at all, or will I even see an improvement of the already very low latency and high random read/write performance.
     
  9. pprior macrumors 65816

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    Aug 1, 2007
    #9
    You didn't read my reply - check the latency data on an intel SSD.

    Now pretend a raid-0 array will double or even triple latency (it doesn't) - it still would BLOW AWAY the latency on any hard disk by 100fold.

    That is what I meant - the latency on an SSD is so low that increasing it somewhat makes no signficant difference, wheras with hard drives it makes a significant performance difference, hence rotational speed performance differences.
     
  10. funkahdafi thread starter macrumors 6502

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    #10
    sorry, I must have overlooked that.

    well. I think I am going to raid them. :D

    Now all that needs to happen is the rumored price drop on the X25. Already ordered the MaxUpgrades module that fits two of those beasts into the empty optical drive by of the Mac Pro.

    Thanks for all your replies guys.

    Cheers.
     
  11. akm3 macrumors 68020

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    #11
    You said what I said, but sounded smarter. I got called a witch :)
     
  12. nanofrog macrumors G4

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    May 6, 2008
    #12
    Latencies will increase due to I/O processing, but in the case of SSD, it won't be as much as a mechanical drive. ;)

    Random Access times of the drives won't change. RAID doesn't change the laws of physics. :p
     
  13. qveda macrumors regular

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    Sep 8, 2008
    #13
    Most of the posts on this thread are more "advanced" that what I am considering. Hopefully my question is still appropriate.

    I have a 2008 MacPro with the standard 320gb OS/applications drive. (I also have an external backup drive). I am interested in overall performance, and for photography (photoshop etc) in particular.

    Is it fairly easy to replace the internal 320gb hard drive with an SSD (perhaps 80gb) as the boot/OS drive, and then use the 320gb as a second internal drive for applications and data.

    does that make sense? recommended?
     
  14. funkahdafi thread starter macrumors 6502

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    #14
    yes, makes perfect sense. go for it! it's very easy too. if the stuff that's on your current hard drive will fit on the SSD you want to buy, you can simply clone the hard drive to the SSD.

    If it doesn't fit, you could do a fresh install of OS X onto the SSD and then use migration wizard to transfer your settings from the hard drive. Or just do a clean install.

    Either way, it'll be some work and will probably take you a couple of hours until you have everything running, but it'll be worth it. Once you're done, you could use the 320 gig as a single data drive, or partition it into two partitions, using one for data and the other one for time machine. Many possibilities.
     
  15. gesundheit macrumors member

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    Oct 28, 2004
    #15
    80GB is plenty big for the OS and, I would think, most people's collection of apps (obviously there are folks with greater needs). That's how I'm set up, with room for a 20GB Bootcamp partition.
     
  16. funkahdafi thread starter macrumors 6502

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    #16
    Well that really depends on what you install and what you keep on your system partition. If you want to keep things like your iTunes, iPhoto, Aperture etc. libraries on your startup disk then you obviously need more space.

    But I agree, for OS and apps only, with your user folder relocated to another drive, 80 gigs is more than enough. You might even consider the 30 gig version.
     
  17. gesundheit macrumors member

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    Oct 28, 2004
    #17
    Exactly my point. This only works with a lean OS/apps installed on the SSD as boot. No one is going to start putting their iTunes libraries on there at these prices, those songs won't be 99¢ any more! (I'd need 200GB just for my music)
     
  18. QuantumLo0p macrumors 6502a

    QuantumLo0p

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    #18
    Here is a recent MR thread...http://forums.macrumors.com/showthread.php?t=685461
     

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