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Does a large SSD (e.g. 250 GB) perform better compared to a smaller one, such as a 64 GB one?

Or, better put, is the difference in read/write speed (esp. on random operations) enough to justify the price of a larger SSD, if my only use will be system disk for OS X / Linux?

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    The size of a SSD doe snot determine how it will perform. The actual specifications of the device does. Newer revisions or models of a product will perform better then an older revision or model.
    – Ramhound
    Sep 23, 2015 at 12:40
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    This might be vaguely true within the same product line. You'll want to confirm the specs though
    – Journeyman Geek
    Sep 23, 2015 at 13:02

2 Answers 2

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In most cases, the performance is determined by the number (and performance characteristics) of NAND chips in the SSD.

When comparing SSD's from the same product line, it is often the case, that they're using the same NAND chips in the SSD, but that the larger capacity ones have more chips than the smaller capacity ones.

In those cases, the larger capacity ones will often times have much better performance than the smaller capacity ones.

As an example look at this:

4KB Random read (QD32): Up to 98,000 IOPS (500GB/750GB/1TB); up to 97,000 IOPS; (250GB); up to 94,000 IOPS (120GB)

4KB Random write (QD32): Up to 90,000 IOPS (500GB/750GB/1TB); up to 66,000 IOPS (250GB); up to 35,000 IOPS (120GB)

which is taken from the cnet review of the Samsung 840 series of SSD's

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    This is a good answer. Attempts to explain what my comment was indicating. The difference in IOPS between those models can easily be explained by the fact the larger devices often only are offered in M.2 versions ( i.e. Samsung 950 Pro )
    – Ramhound
    Sep 23, 2015 at 13:16
  • Interesting, thank you. Is the difference noticeable in everyday use on a machine used for basic tasks (browsing, movies)?
    – Laurent
    Sep 23, 2015 at 17:11
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As Ramhound has written in the comments, the size does not determine speed performance. When purchasing the SSD you should look at the specifications which should list both read and write speeds.

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    this is wrong. Larger SSD have faster write speeds because they have more channels which can be used in parallel. Sep 23, 2015 at 16:48
  • There are plenty of larger SSD that have a slower write speeds then a smaller one. You can't just look at the size and judge the speed on that alone. For example, ADATA PP SP900 is a 64GB drive with speeds of 550/505 while the ADATA PP SP550 is a 120GB drive with speeds of 560/410. Why? Diffrent models with diffrent components. Size is not everything. Sep 23, 2015 at 17:20
  • you have to compare the same SSD in 2 different sizes, not different ones with different controllers. Sep 24, 2015 at 4:23
  • There is nothing in the original question to indicate that it is limited to SSD that are identical aside from size. Size alone does not determine speed. There are also identical SSD (aside from size) where speed is identical. There are even some cases where the larger SSD is actually slower, like the Corsair Force GS Series 240GB vs 480GB, where both read and writes are slower on the larger drives. Sep 24, 2015 at 5:23
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    you have to compare the same SSDs otherwise you compare apple and oranges. the amount of NAND chips impacts the speed: "With a hard drive, data is basically written serially, down a single channel. The stream may be interrupted by existing data, but ideally it's all written in a neat, uninterrupted line. Inside an SSD, data is written in a scattershot, parallel fashion down multiple channels to the multiple NAND chips at once. The more NAND chips an SSD has, the more channels it has to write/read across, and the faster the drive will be." bit.ly/1NWtsSr. Sep 24, 2015 at 16:03

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