3 GB/s

Discussion in 'Mac Accessories' started by Jimmy Guphanti, Nov 25, 2012.

  1. simsaladimbamba

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    #2
    Most mechanical HDDs are offering speeds from 65 MB/s (2.5" 5.400 RPM HDD) to 125 MB/s (3.5" 7.200 RPM HDD).
    Current SSDs offer between 400 to 600 MB/s.

    Therefore you will only achieve 3 GB/s speeds via some complicated RAID system, and you probably do not need such speeds anyway, unless you transfer TBs of data DAILY.
     
  2. Jimmy Guphanti thread starter macrumors 6502

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    #3
    In that case, what is the best, fastest, FireWire 800 drive out there?
     
  3. simsaladimbamba

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    #4
    Firewire 800 will limit you to 65 to 75 MB/s. As for the best, I do not know, I have had plenty of varying degrees of speed, depending on the used chipset I guess.
    The fastest I have are WD My Book Studio HDDs, but you could also just buy an external enclosure like the ones OWC or MacAlly offer and buy a bare HDD yourself.

    If you have Thunderbolt or USB 3.0, a USB 3.0 or Thunderbolt HDD or SSD will be faster.

    And I now figured, that with "3 GB/s" you did not mean "GigaByte per second" but "Gigabit per second" (Gb/s), which is the theoretical throughput of S-ATA 3.0 Gbps (S-ATA II), but no HDD will even saturate S-ATA 1.5 Gbps (S-ATA I).

    While not related to HDD transfer speeds, this might shed some light on the difference between Bytes per second and bits per second (8 bits = 1 Byte).
     
  4. Jimmy Guphanti thread starter macrumors 6502

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    #5
    What about this?: http://www.macmall.com/p/LaCie-External-Hard-Drives/product~DPNo~9105214~pdp.hcjeaji?source=mwbgoogleshop&adtype=pla&kw={keyword}&gclid=COP5ldz96rMCFQSg4AoduisA_w

    It seems like companies like to flaunt theoretical numbers like 800 MB/s and 10 GB/s when in reality it is much slower. On that LaCie drive, they say Interface : 2 x Thunderbolt 10Gb/s

    But then...

    HDD (R/W):*
    • 2TB: 190MB/s / 190MB/s


    I understand that HDDs are more limited than SSDs, but SSDs are too expensive now.
     
  5. simsaladimbamba

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    #6
    They use "Mb/s"or "Gb/s" and not "MB/s" or "GB/s", the difference between the two, that "Mb" refers to "Megabit" and "MB" refers to MegaByte", and again, 1 Byte is 8 bit, thus "800 Mb/s" are "100 MB/s", theoretically.
    Practically there is some overhead, thus always expect 20% less of that.

    As you can see from your probably copied and now bolded part, it is listed in "Gb/s".
    That is because two 1 TB HDDs are combined into one 2 TB volume via RAID, which means the information is striped between two 1 TB HDDs, thus the faster speed, but also the much lower security, since when one loses one HDD out of the two, the other is worthless too.
     
  6. Jimmy Guphanti thread starter macrumors 6502

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    #7
    Sorry, I am bad at the whole bit/byte thing. I am referring to the standard "b" that is used when referring to the size of an iPad for example. With that being said, around what speed could I get with that LaCie Thunderbolt Drive?
     
  7. simsaladimbamba

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    #8
    The standard "b" is referring to "bit", the iPad's storage capacity is measure in "Byte", thus the "16 GB / 32 GB / 64 GB" monikers.

    As for speed, if the LaCie uses good HDDs, you should get around 100 MB/s via Thunderbolt if you have a Thunderbolt equipped Mac (all Macs since 2011 except Mac Pro).

    Maybe tell us what you want to do with the external HDD, maybe a Firewire 800 HDD would more than suffice (sorry for brining up TB again in one of my earlier posts).
     
  8. Jimmy Guphanti thread starter macrumors 6502

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    #9
    That's fine, you have been exceptionally helpful. I at first wanted to use it in place of the 1TB HDD built into my iMac if it would be faster but after testing the disk speeds, it appears to be exactly the same, the HDD in my iMac is at the same speed as that LaCie one. In that case, I would use the LaCie drive for Time Machine backups and storage. I currently am using a USB 2.0 drive that runs at 30 MB (bytes) per second, and takes about 6 hours to restore or backup my Mac. With the LaCie Thunderbolt drive, I could daisy chain my other display, and backup my computer at around 100-200 MB/s in around 45 Minutes. I at least hope it works like that.
     

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