[chuug] Fwd: Linux filesystem recovery

[Jeff Uphoff]

"PM" == Pat Murphy <ppmurphy at gmail.com> writes:

PM> It may not be the case now, but in times past there was quite a bit of
PM> inefficiency in using "cat" which used to fetch a single character at
PM> a time.  With dd, the I/O is blocked, and with bs= (or ibs=, obs=) the
PM> blocksize can be optimally configured for efficiency.

cat pokes at the system's stat structure to find an efficient default
blocksize for I/O:

         struct stat {
	     ...
             blksize_t st_blksize; /* blocksize for filesystem I/O */

On my 32-bit laptop, it's 4k (same as the page size); on one of my
x86_64 boxes, it's 32k.

--Up.

-- 
Jeff Uphoff, Charlottesville, VA
Senior Engineer, rPath, Inc.