SSD Partitioning OP/Trim recommendations

Robert Moskowitz rgm at
Wed Dec 18 20:38:25 UTC 2013

On 12/18/2013 03:09 PM, Chris Murphy wrote:
> On Dec 18, 2013, at 11:50 AM, Robert Moskowitz <rgm at 
> <mailto:rgm at>> wrote:
>> On 12/18/2013 01:32 PM, Chris Murphy wrote:
>>> On Dec 18, 2013, at 6:03 AM, Robert Moskowitz <rgm at 
>>> <mailto:rgm at>> wrote:
>>>> On 12/18/2013 04:41 AM, John Obaterspok wrote:
>>>>> Hello,
>>>>> I'm going to setup F20 with a new SSD disk (256gb Samsung 840 PRO) 
>>>>> and was wondering about best practices for Over Provisioning 
>>>>> during partitioning.
>>>> hmmm.  I just ordered a Crucial M500 256GB SSD for my new install.  
>>>> I thought I would have it all to work with (currently using a 320GB 
>>>> HD, so that is a 64GB reduction already).  Are you implying here 
>>>> that you need to not use all of the SSD drive so that it has some 
>>>> swap around?
>>>> I chose the M500 over the 840 based on price and reviews.  The M500 
>>>> uses MLC NAND compared to the 840 using TLC NAND.
>>> FYI, be aware there appears to be a queued TRIM bug with the M500 
>>> where it may be causing silent data corruption. I wouldn't use 
>>> discard on this, or any, SSD, in production until it's been well tested.
>> Seems like a workaround was posted yesterday?  So since I am still 
>> waiting for the drive to show up on my porch…
> Yes. Although I'm uncertain whether we get queued TRIM "for free" with 
> a SATA rev 3.0 controller, or if that means such drives use the SATA 
> rev 3.0 non-queued TRIM? I'm under the impression that to get SATA rev 
> 3.1 queued TRIM that the drive and the controller it plugs into, and 
> libata all need to support SATA rev 3.1. So I don't actually fully 
> understand the problem, but it sounds like a firmware bug to me. 
> Suffice to say, with Windows having enabled TRIM by default for all 
> SSDs, if a drive is corrupting its data, this ought to be quickly 
> remedied with a firmware update I'd think.

My Lenovo x120e supposedly has the sata3 chipset, but only sata2 
enabled.  According to a few forums that I found when looking for what 
type of drive to buy for this laptop.  Some think the sata2 option is to 
upsell the x220.

So perhaps TRIM is even less important to me.

But first I have to get f20 working reasonably on my Asus before 
installing on my Lenovo.  And I have to figure out a few things. Not 
being able to specify the update repo at install was painful.

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