Mac Pro RAID Card vs. SSD

Discussion in 'Mac Pro' started by m021478, Apr 22, 2011.

  1. m021478 macrumors 6502

    Joined:
    Nov 23, 2007
    #1
    Planning to purchase a new Mac Pro and was debating adding the optional RAID card (which only allows non-SSD drives - i.e. 1TB or 2TB HDD).

    How would the performance of this machine loaded with the RAID card and 4 1TB drives compare to the same machine in which the primary OS is running off of a 512GB SSD?

    Any advice would be greatly appreciated. This is a big purchase for me and I really don't want to make the wrong decision here
     
  2. cosmos macrumors regular

    cosmos

    Joined:
    Dec 17, 2003
    Location:
    Cincinnati, Ohio
    #2
    I think that you are a little confused in either your expectations or what you are asking. Either that or I am misunderstanding your question.

    The benefit of RAID is added protection using an array of disks just as the name states vs. a single point of failure using a single drive. SSDs will always be much faster as there are no moving parts as I/O is the slowest portion of any computer.

    What RAID gives you over current SSDs is much larger storage with redundancy in case of a drive failure. SSDs, however, have generally very good reliability but with higher storage costs.

    I believe what you are really wanting is both RAID for storage and an SSD for the system drive. This gives you both performance and storage. In either case, do not neglect offsite (or secure onsite) backups no matter what you choose.
     
  3. weneversleep macrumors newbie

    Joined:
    Feb 7, 2011
    #3
    I think this is a valid question, to compare speeds of SSD vs. RAID, IF you're talking about RAID 0.

    RAID 0 will give you (almost) n * <single_drive_speed> for reads and (to a slightly lesser extent) writes, where n=# of physical drives in the RAID array.

    Current 7200 RPM SATA II drives give ~100 MB/s read speeds, some a little more, some a little less. 2nd gen SSD drives are in the 200 - 250 MB/s read speed range, depending on controller type and manufacturer. (3rd gen SSD SATA III drives are in the 500+ MB/s range, but you'll have to have a SATA III port to realize those speeds).

    So, you could almost match the speed of a 2nd gen SATA II drive with a couple of 7200 RPM spinning platter drives. (I know this, because I'm running a 2 slice RAID array with these drives, and a 2nd gen SSD, and the read/write speeds are very similar.) Add more physical drives, and you'll increase the speeds, up to the SATA bus limit.

    Of course, the tradeoff with RAID 0 is reliability. If one of those drives fail, you lose the entire array. So, you better have good backups.

    Personally, I have my SSD (OWC 115 GB 2nd gen Sandforce SL-1200) as the system/applications drive, and a couple of 2TB spinning platter drives in a RAID 0 array as my data drives. I also have my data backed up in numerous places and using different methods (TM, CrashPlan, synced to my Windows 2008R2 server, synced to my WHS server, offsite drives, etc... yes, I'm a backup freak, and I write backup software for a living)
     
  4. weneversleep macrumors newbie

    Joined:
    Feb 7, 2011
    #4
    One more thing: I'd skip the Mac RAID card and just use the software RAID. In a Mac Pro, you have plenty of processing power for the write calculations, and the Apple RAID implementation is pretty good.
     
  5. nanofrog macrumors G4

    Joined:
    May 6, 2008
    #5
    First off, the Apple RAID Pro is junk (expensive, slow, only works with one OS, and still has battery issues), so stay away from it. If you do need a RAID card, there are much better alternatives via 3rd party companies.

    As per performance, it all depends on what you're trying to do.

    Now based on 4x 1TB disks, and lets say they can do 100MB/s each:
    • RAID 0 = n * 100MB/s = 400MB/s (no redundancy at all = one disk dies, all data is gone)
    • RAID 5 (requires a RAID card) = (n - 1) * 100MB/s * .85 = 255MB/s (redundancy of n = 1, so if one disk dies, the data is still intact)
    • Single SSD (typical) = ~250MB/s or so
    From a basic standpoint, an SSD is faster at random access (what an OS and loading applications require for speed) performance than any mechanical disk. SSD's are also really good performers for sequential throughputs for a single disk. But where this runs into a problem, is in terms of costs. You can end up with more capacity, greater throughputs, and some level of redundancy using multiple mechanical disks in a RAID configuration for similar funds to what you could do with SSD's.

    If you give detailed information as to what you're doing, we can help you further (cosmos is definitely thinking along the lines I am), but the details can help get you into the right setup (level as well as hardware needed to do it).

    For example:
    • What is your intended use of the system?
    • What are your capacity requirements (now and say over the next 3 years)?
    • What sort of throughputs do you need (this can be figured out off of usage pattern, but if you know the throughput in MB/s, it's much easier)?
    • Do you need redundancy, and if so, how much (if you know; again, answers to other questions can help figure this out, but it's clearer if you know directly)?
    • What kind of budget are you working with (keep in mind, a RAID card and enterprise disks aren't cheap)?
     
  6. philipma1957 macrumors 603

    philipma1957

    Joined:
    Apr 13, 2010
    Location:
    Howell, New Jersey
    #6
    you mention a 512 ssd as an alternative. My guess is you mean apple's mac pro ssd option. for around 1200 or 1400 dollars. Intel has come out with a 600gb ssd for about 1060. It is larger and faster then apple's offer. I have the 300gb version. I am going to buy the 600gb version shortly. Hers is a link for it:

    http://cgi.ebay.com/NEW-Intel-SSDSA...e_Internal&hash=item588dae1c02#ht_2405wt_1250

    buy dot com is a large seller and you would get a full 3 year warranty with the drive
     

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