Re: SSD gives disappointing speed up on OSX

On 02/02/2016 07:32 PM, Bill Ross wrote:
> I have a program that inserts 50M records of about 30 bytes each, with
> some simple indexing, using about 5 GB of disk, layout shown below. When
> I run the program without the inserts, it takes a few seconds to do just
> the calculation part.
>
> With inserts, it takes about 90 minutes to run on my macbook pro (2012)
> with a spinning disk and 8G memory. Since CPU was running at 40% idle, I
> figured this must be due to waiting on disk, so I swapped in an SSD. Now
> on the console I see 6 Mb/s negotiated link speed on disk, vs. 3 Mb/s
> before.

So, your basic problem is going to be that OSX doesn't have a decent
filesystem to offer. HFS+ was created 18 years ago, and it was a hack
on top of an older HFS. At its heart, it's still basically a DOS-era
16-bit filesystem. This means that as long as you are on Mac OS, you
can assume that writes will be slow no matter how good your hardware is.

Supposedly you can still run ZFS on OSX, which might help you. I
haven't done it, though.

--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)