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http://www.seagate.com/internal-hard-drives/solid-state-hybrid/desktop-solid-state-hybrid-drive/

Some says that using hybrid drive is 4 times faster.

Some says it depend on data read. SSD is only faster for random access while HD is just as fast for continuous data.

I wonder which one is right.

How much faster is SSD compared to regular hard drive and by how much?

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  • "while HD is just as fast" -- The proper acronym is HDD, for hard-disk drive. I.E. the drive contains hard disks (aka platters).
    – sawdust
    Aug 25, 2014 at 7:10

2 Answers 2

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Some say that using hybrid drive is 4 times faster.

It may be four times faster in one specific scenario.

E.g. windows boot might be four times faster after the disk has learned which files to cache on the SSD part. (Windows boot involves a lot of small disk reads and thus benifits hugely from a SSD).

Some say it depend on data read. A SSD is only faster for random access while a HDD is just as fast for continuous data.

Almost.

HDD are good for sequential reads. Current harddisk can do 100MB/sec to 200MB/sec when doing these reads. (E.g. reading an iso). *

SSD are also good at reading large files. They reach much higher speeds then convential harddisks.

However they truely shine with random access. 4K random disk access on a classic rotating harddisk might drop the speed down to 1 or 2 megabyte per second (yes, that slow). Most SSDs I tested still do 7 - 8 MB/sec under the same scenarios.


Needless to say. SSDs are currently significantly more expensive. (e.g. €25 for a 40GB SSD - enough to hold the OS but not much more). To combine the benefits of cheap but slower storage and fast but expensive access you need both of them. This results in the kind of drive you mentioned at the top of your post. Those hybrids remember which files you read often and cache [part of those] on the SSD part. If cached the access will be much faster. If not it performs as a regular drive.

I wonder which one is right.

I hope I answered this part.

How much faster is SSD compared to regular hard drive and by how much?

That depends on which drive and which SSD you are comparing. The difference is large enough that (for me) it is worth it to get a small SSD (say 80GB) and use that for the OS and for my programs. (My pictures, security cam recordings etc are left on classic rotating media).


*These values obviously differ per drive and the drives will get faster over time. At the time of writing 100MB/sec is a decent speed for a 7200k RPM SATA drive and a high end 15k RPM SAS drive might reach 200MB/sec on its outer tracks.

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  • "outer platters" -- There's no such thing. You mean outer cylinders or tracks. "four times shorter" -- A common but illogical construct. Multiplying something (by a factor larger than unity) doesn't make it smaller or shorter.
    – sawdust
    Aug 25, 2014 at 6:39
  • Yes, that is what I meant. ENOTENOUGHCOFFEE.
    – Hennes
    Aug 25, 2014 at 7:03
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To some extent it depends on the workload, the SSD, and the hard drive you are comparing it to. But order of magnitute, SSDs are around 10 to 100 times faster than HDs.

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  • Ofcourse, if the SSD isn't a cheap one... Aug 25, 2014 at 5:44

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