Filesystem fragmentation and scatter-gather DMA

Ric Wheeler ric at
Mon Mar 17 13:45:54 UTC 2008

William Tambe wrote:
> Is the delay due to mechanical parts or the electronics gathering the fragments?
> Would that same delay still apply to a solid state drive? Since a
> solid state drive is really just a slower version of system memory
> (Please correct me if I am wrong).

With spinning media,the big cost is moving the physical heads of the drive.

With an SSD FLASH-based device, you might also prefer having contiguous 
writes since flash needs to be erased before the write can happen (and 
that occurs in chunks). Non-contiguous writes of single sectors would 
have a high chance of causing extra erasures & read-modify-writes...


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