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#1 2019-10-24 23:23:23

Jimbaker
New Member
Registered: 2019-10-24
Posts: 1

Is the SSD "20% Free Space"

I know SSD's get slower once full due to them having to erase/trim cells before they can write.

However, even today people are still saying that you should leave 20% of your SSD with no partition.

This seems like an awful lot of storage to throw away, especially with large 1TB SSD's. Surely technologies like over provisioning make this rule less important?

Does anyone have any benchmarks on SSD performance at different levels of free space? For example, performance at 10% free space vs 20% vs 30%. Would be interested to see how much truth there is in this rule of thumb.

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#2 2019-10-25 05:51:21

ohnonot
...again
Registered: 2015-09-29
Posts: 4,092
Website

Re: Is the SSD "20% Free Space"

Hello and welcome to BL forums!

How would you even benchmark that in a meaningful way, with so many different SSD models, computer systems, filesystems etc. etc....

SSDs are ubiquitous, and have been around for long enough that all such tweaks should long since have become part of the hardware itself, or the kernel & filesystems, if they make sense.
Here's some reading to get you started, but even that seems to be a bit outdated on the matter.
Anyhow, I remember reading somewhere: you don't have to take special care of SSDs anymore nowadays.

But of course, why not tweak some more. It's a bit like overclocking I guess.

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#3 2019-10-25 14:13:56

linux_user
Member
Registered: 2016-11-04
Posts: 414

Re: Is the SSD "20% Free Space"

I have a 256GB SSD, and only about 15GB is free now (that's ~6%). From my usage, I don't notice any lag. This doesn't mean that there is or there isn't any lag; just that if there is, it is quite unnoticeable.

On the other hand, I haven't come across any article suggesting that not leaving ~20% free space is bad for the SSD in terms of it's health; just that it'll make it slow. For 200GB is a great deal of space not to use in a 1TB SSD. So, I would suggest using it until you start feeling the lag.

Last edited by linux_user (2019-10-25 14:18:05)


"Blind faith to authority is the greatest enemy of truth."

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#4 2019-10-26 02:56:47

johnraff
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From: Nagoya, Japan
Registered: 2015-09-09
Posts: 5,958
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Re: Is the SSD "20% Free Space"

Don't SSDs have some built-in extra space?


John
--------------------
( a boring Japan blog , Japan Links, idle twitterings  and GitStuff )
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#5 2019-10-26 06:54:30

ohnonot
...again
Registered: 2015-09-29
Posts: 4,092
Website

Re: Is the SSD "20% Free Space"

^ That's what I thought I remembered too.

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#6 2019-10-26 08:41:45

linux_user
Member
Registered: 2016-11-04
Posts: 414

Re: Is the SSD "20% Free Space"

From Kingston's explanation of their method of over-provisioning, I reckon that any SSD/flash device of binary size pattern would be an device without over-provisioning and devices of decimal size pattern will have over-provisioning built. ie: devices sold as 60GB, 120GB, 240GB, 480GB etc. would have over-provisioning feature; and devices sold as 64GB, 128GB, 256GB, 512GB etc. would not have over-provisioning feature. There are SSDs in the market marked with both decimal and binary base size.

Here is another article by Seagate that says that the difference between GB and GiB is what is reserved for over-positioning. As they claim, SSDs are made from memory devices which usually are made with the binary naming conventions. So they have 1024 bytes in a KB unlike HDD manufacturing. But since SSDs are storage devices they market it using decimal naming convention and the space difference of these naming convention is used for over-provisioning. So by their logic, all Seagate drives have over-provisioning feature.

This product listing on Amazon has a drop down list to choose the preferred size to order. The options contains closely related sizes like 60GB and 64GB, 120Gb and 128GB, 240GB, 250GB and 256GB, 480GB and 500GB. So, as per Kingston's explanation, these are drives with and without over-provisioning. But according to Seagate's explanation, all of them should have over-provisioning since every drive have a higher GiB value. I guess it's better to limit a company's explanation to their own drives. smile

=============================
A funny side note on how I messed up my LAMP localhost by reading @ohonot's answer. I saw the link to his blog on his signature, visited it, saw that the blog was provided by Pico, visited their website, learnt that it's a flat file nodb cms, got intrigued to try it, downloaded it, used Thunar's 'Extract to' context menu, and by mistake extracted it to /var/www instead of /var/www/folder. Boom! Localhost is now Pico set up instead of a list of my projects.

Last edited by linux_user (2019-10-27 11:48:44)


"Blind faith to authority is the greatest enemy of truth."

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#7 2019-10-27 11:37:26

ohnonot
...again
Registered: 2015-09-29
Posts: 4,092
Website

Re: Is the SSD "20% Free Space"

Overprovisioning seems to be the keyword here.
It seems to confirm my suspicion that all this stuff is "bult-in anyhow nowadays".
I wonder what OP has to say about all this?

linux_user wrote:

A funny side note on how I messed up my LAMP localhost by reading @ohonot's answer. I saw the link to his blog on his signature, visited it, saw that the blog was provided by Pico, visited their website, learnt that it's a flat db blog, got intrigued to try it, downloaded it, used Thunar's 'Extract to' context menu, and by mistake extracted it to /var/www instead of /var/www/folder. Boom! Localhost is now Pico set up instead of a list of my projects.

Ouch. Don't blame me or pico, blame Thunar! (or the PEBKAC of course)
btw, pico is a NO db CMS!

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#8 2019-10-27 11:48:05

linux_user
Member
Registered: 2016-11-04
Posts: 414

Re: Is the SSD "20% Free Space"

ohnonot wrote:

Ouch. Don't blame me or pico, blame Thunar! (or the PEBKAC of course)
btw, pico is a NO db CMS!

I blame myself mad

Sorry about that typo, meant 'flat file'. Corrected it.


"Blind faith to authority is the greatest enemy of truth."

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