[mythtv-users] EXT4 vs XFS

Mark Lord mythtv at rtr.ca
Thu Nov 17 17:59:02 UTC 2011

On 11-11-17 05:24 AM, phipps-hutton at sky.com wrote:
> Wear and tear:
> TRIM support means that the kernel tells the drive controller that a  
> sector is unused and the kernel will not expect the sector contents to  
> be preserved. That's all it does. SSD controllers use this information  
> to erase the sectors and put them on the list of erased sectors. They  
> do this when they have nothing to do and they maintain the list in  
> permanent storage...

That's certainly a good guess at what happens, and it's exactly what
just about all of us expected.  Until some of us actually tried it
and measured things.

Most SSDs (but not all) perform immedate erase cycles in response to TRIM,
and those are done synchronously (blocking other I/O until done).

All of the Gen I/II Sandforce controllers and the Indilinx "Barefoot"
have been observed to behave this way, as has the controller (Samsung?)
in the Kingston V100 drive.

And others.

I think the Intel SSDs may be the only ones known to not take a huge
penalty for TRIM.


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