Replacing Drive with SSD

RW rwmaillists at
Mon Aug 31 14:23:59 UTC 2015

On Mon, 31 Aug 2015 09:41:07 -0400
Quartz wrote:

> > Making a partition for free space is one way. Another way is to
> > leave part of the drive unpartitioned. Either one just guarantees
> > there is a good supply of unused blocks available to the drive.
> I'm not super well versed on exactly how SSD TRIM works. How does the 
> drive in question know which blocks are or aren't free, isn't that a 
> function of the filesystem? For that matter, how does the drive even 
> "know" which parts are or aren't partitioned, it's not like they're 
> programmed to understand MBR vs GPT, etc.

Physical blocks are assigned to logical sectors on write.
Partitioning a device and putting UFS on it doesn't write into the free
space on a filesystem or any unpartitioned  space. 

> How does the system 
> communicate to the drive firmware layer which blocks are in use?

When a file is deleted, the OS can use TRIM to tell the device which
sectors not longer contain data. 

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