There is no standard. 50?150 Mb/s for SATA, 300 for SSD
An iMac was running intolerably slow. Would take minutes to boot, 30 seconds for clicks to take effect. I found Blackmagic Disk Speed Test which will test the read write speed of your Mac.
?Blackmagic Disk Speed Test
?Disk Speed Test is an easy to use tool to quickly measure and certify your disk performance for working with high?
Testing an iMac with a 1 TB SATA and the read write speeds were 25 and 30.
After googling around I found that is not a good speed.
The top speed is 300MB/s SATA interface but no drives write that fast. The read/write of modern hard drives are in the 50?150MB/s range. There is not really a standard.
From this article, I see that an external HD connected via USB would be around 25MB/s read write, and an SSD should be around 200 or 300 MB/s read write.
What?s a good score?
While a standard external hard drive connected to a Mac via USB 2.0 won?t reach speeds of more than 25?30MB/s (extremely slow), upgrading your built-in hard drive to an SSD should see significant gains in performance. Take our 2011 iMac, for example: while the built-in hard drive reaches speeds of up to 90MB/s, our external SSD connected via Thunderbolt achieves up to 420MB/s.
The difference in speed is dramatic, and is immediately noticeable in everyday use. In fact, it?s probably the main reason that Apple has replaced traditional hard drives with solid state drives across its entire MacBook range. If you?ve got a slow hard drive, it might be looking into upgrading to an SSD.
I then ran Blackmagic on a Macbook with an SSD and got read write speeds of 408 and 718 MB/s.
I know the SATA drive won?t hit those, but it should be better than an external hard drive.
If you run Blackmagic, comment below with your HD type and size and what your speeds were.