[mythtv-users] EXT4 vs XFS

Mark Lord mythtv at rtr.ca
Thu Nov 17 18:19:49 UTC 2011

On 11-11-17 05:24 AM, phipps-hutton at sky.com wrote:
> TRIM support was put in because SSD disks slow down after a while if  
> you don't have it. When you buy a new SSD all the sectors are on the  
> erased list and it writes like a demon.... until you have written more  
> than one disks worth which in real life happens after a few days.  
> After that if you don't have TRIM support there won't be any sectors  
> on the erased list and each write will require an erase first and  
> performance will drop off.

Pretty much all SSDs on the market do automatic background erase operations,
pre-erasing reallocated blocks when otherwise idle.  Many SSDs are also fancier,
performing full "background garbage collection" (their term, not mine).

The result of all of that is nearly as good as explicit TRIMs,
but without the operating system overhead and latency of
trying to do "trim on the fly" amidst other operations.

The "background garbage collection" worries me a bit, because the drive
firmware has no idea when I'm about to disconnect power or hit the
system reset button.  But there's nothing to be done about it,
as even the drives with TRIM support still do the background stuff.


More information about the mythtv-users mailing list