SSD compared to an HDD in terms of speed

By thomja ยท 6 replies
Oct 29, 2012
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  1. Hello

    I have a question regarding the speed of an HDD. How fast would an HDD need to be to match the write speed of a 520mb/s SSD?

    Is there anyway for me to look this up somewhere with a converter or something?

  2. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,742   +421

    Not sure I understand the question. The mechanical drive would have to be just as fast 520mb/sec. Unless you mean spin speed, and thats somewhat unrelated.

    What you might be questioning is megabits vs megabytes. Megabit should be written as Mb, and Megabyte is MB. But in reality there is a ton of misuse of the correct capitalization and ways to write it. I'm sure I've screwed it up a few times on these boards myself. So in a bit to byte conversion, just divide the bit number by 8.
  3. slh28

    slh28 TechSpot Paladin Posts: 1,706   +172

    I think he means the spin speed. Or how many HDD's you'd need in RAID 0.

    But regardless, the most impressive specs of an SSD are not the "headline" 500+ MB/s sequential read/write speeds but the super quick random read/writes and low access times (compared to a mechanical HDD).
  4. cliffordcooley

    cliffordcooley TS Guardian Fighter Posts: 9,728   +3,701

    Yes this is confusing, as the answer is found within the question.

    If I am following you correctly, you are asking what the speed ratio is between an SSD that has a speed of 520MB/s and a top-of-line HDD. The ration would be in the neighborhood of 4:1, depending heavily on the SSD and HDD you are comparing and the type of test you are using.
  5. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,742   +421

    But spin speed doesn't always correlate as faster spin faster read, especially when considering the production date of the drive. There are some 15,000 rpm drives out there, here is something from 5 years ago with drives having 128MB/sec transfer speeds and in the 5-6ms response times (depending on the drive). But those are very much enterprise level drives. I'd guess one of my 'green' 1.5-2TB drives at 5900 rpm are faster than some of the 500 gig drives I've had that were 7200 rpm.
  6. tipstir

    tipstir TS Ambassador Posts: 2,475   +126

    SSD are what are used in Tablet. They tend to degrade in performance in time because they're based on memory chips appose to hardware metal disc. SSD are quicker to access data in I/O sessions. Reads/Writes would be faster than HDD. There are some HDD Hybrid SSD those give you both advantages. HDD can reach into the high TB where the SSD max out 250GB. SSD in laptop makes the desktop and laptop run a bit quicker than SATA II 3.0 or SATA III 6.0. You can give it a shot and see if your happy with using one. Before you go 100% replacement of what you using now.
  7. thomja

    thomja TS Rookie Topic Starter Posts: 87

    Thanks for all the responds! Very helpfull!

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