memstick.img is bloated with 7% 2K blocks of nulls

[Julian H. Stacey]

memstick.img wastes 7% with 2K blocks of nulls.
shown by:
	8f -b 0 -n 2048 -l -f Fr*
	http://berklix.com/~jhs/src/bsd/jhs/bin/public/8f/	8f.c 8f.1

	FreeBSD-8.1-RELEASE-amd64-bootonly.iso: 	   543
	FreeBSD-8.1-RELEASE-amd64-disc1.iso:		   543
	FreeBSD-8.1-RELEASE-amd64-dvd1.iso:		  1125
	FreeBSD-8.1-RELEASE-amd64-livefs.iso:		  1109
	FreeBSD-8.1-RELEASE-amd64-memstick.img: 	 38722
	FreeBSD-8.1-RELEASE-i386-bootonly.iso:		   511
	FreeBSD-8.1-RELEASE-i386-disc1.iso:		   511
	FreeBSD-8.1-RELEASE-i386-dvd1.iso:		   865
	FreeBSD-8.1-RELEASE-i386-dvd1.iso:		   893
	FreeBSD-8.1-RELEASE-i386-livefs.iso:		   850
	FreeBSD-8.1-RELEASE-i386-memstick.img:		 34066
	FreeBSD-8.2-RC3-amd64-bootonly.iso:		   594
	FreeBSD-8.2-RC3-amd64-disc1.iso:		   594
	FreeBSD-8.2-RC3-amd64-dvd1.iso: 		  1167
	FreeBSD-8.2-RC3-amd64-livefs.iso:		  1166
	FreeBSD-8.2-RC3-amd64-memstick.img:		 39216
	FreeBSD-8.2-RC3-i386-bootonly.iso:		   565
	FreeBSD-8.2-RC3-i386-disc1.iso: 		   565
	FreeBSD-8.2-RC3-i386-dvd1.iso:			   906
	FreeBSD-8.2-RC3-i386-livefs.iso:		   905
	FreeBSD-8.2-RC3-i386-memstick.img:		 34521

It's not just one big block of trailing nulls.
od -c FreeBSD-8.2-RC3-i386-memstick.img > tmp.od ; tail tmp.od
  7114017760	@ 244 377 344	Q  \b	* 325  \t 333	y   `	&   '  \n   W
  7114020000   \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
  *
  7114050000
050000 - 020000 = 030000 = 0x3000 = 12288

It's a lot of bursts of null blocks, seen by either:
	grep -n '^*' tmp.od
	8f -f -c -b 0 -n 2048 FreeBSD-8.2-RC3-i386-memstick.img 

The CD & DVD images are not nearly so wasteful, see above.
As near 1G ( 959467520 FreeBSD-8.2-RC3-i386-memstick.img ) it will
soon not fit on 1G sticks.
If its not easy for someone to find & trim, xz compression would at 
least save 27% of transmission bandwidth,
	( dc 702447528 100 * 959467520 / p 73 )
a much higher % than DVD that also uses compression.

PS I sent this to hackers@ rather than re@ as I imagine re@ are
busy with more urgent matters at present :-)

Cheers,
Julian
-- 
Julian Stacey, BSD Unix Linux C Sys Eng Consultants Munich http://berklix.com
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