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-R      Turn on the TRIM enable flag.  If enabled, and if the underlying
             device supports the BIO_DELETE command, the file system 
will send
             a delete request to the underlying device for each freed 
block.
             The trim enable flag is typically set when the underlying 
device
             uses flash-memory as the device can use the delete command to
             pre-zero or at least avoid copying blocks that have been 
deleted.

-E      Use TRIM to erase the file system before creating it.  If used
             and the underlying device supports TRIM, the device's LBAs 
will
             be erased using the TRIM command before the file system is 
cre-
             ated.