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SSD

I have upgraded the storage on my Macbook i7 (2011) to a 1tb SSD and understand that to get optimum performance from the new drive, I should only use 70% of its capacity (due to the repeat nature of write/rewriting of data).

To this end I planned to create 3 partitions: Mavericks on one partition (around 400gb) Yosemite (300gb) with the remaining 300gb as the unused portion. However, Disk Utility, won't allow me to create more than two partitions - so how can I achieve three???


All help appreciated, thanks in advance!

MacBook Pro, OS X Mavericks (10.9.1), MacBook Pro (2010) 2.4ghz 320gb 4gb

Posted on Apr 27, 2015 4:08 PM

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3 replies

Apr 28, 2015 11:37 AM in response to dmac888

I cannot say that I have seen anything that indicates leaving 30% of an SSD free leads to optimum performance. As far as i am concerned it may or may not be true but in the greater scheme of things, based on empirical experience, I don't think that it is important.


I have two MBPs that have 1 TB SSDs that are both 85%+ full and and I detect no adverse performance symptoms. I am inclined to believe that we are dealing with 'a law of diminishing returns' at best. Prior to the installation of the SSDs, I had 1 TB HDDs with one MBP having about 950 MB of data. No detectable performance decline was observed and I suspect the '15% free space rule of thumb' really does not exist for HDDs. That may also may be the case for SSDs but I cannot say so with authority.


If you enable TRIM or allow for 'Garbage Collection' your SSD will perform satisfactorily. My unfounded view is that the differences between a SSD with more than 70% of it's capacity used vs. one with less than 70% of it capacity used is in terms of real world usage going to be virtually undetectable. We may be dealing with differences that require measuring devices to demonstrate such differences which may be very, very small.


It may be analogous to bench test scores of two macs that have similar scores. There may be score differences, but when actually using them, you may not be able to tell which is that 'faster' Mac.


Ciao.

Apr 28, 2015 11:37 AM in response to dmac888

dmac888 wrote:


... However, Disk Utility, won't allow me to create more than two partitions - so how can I achieve three??? ...

Easy answer: you don't have to. 😉 If you leave the space beyond the first two partitions as free space (i.e., unused), you won't be able to get at the space but the SSD's controller can so it gets included in the overprovisioning.


I think the value of increased overprovisioning can be seen in the performance graphs here. The web page lets you pick different amounts of overprovisioning with different SSDs to see the difference.


And, as OGELTHORPE points out, TRIM is beneficial, and since you're not using Yosemite, you can do that safely.

SSD

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