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mkulzma(8)		  BSD System Manager's Manual		    mkulzma(8)

     mkulzma --	compress disk image for	use with geom_uncompress(4) class

     mkulzma [-v] [-o outfile] [-s cluster_size] infile

     The mkulzma utility compresses a disk image file so that the
     geom_uncompress(4)	class will be able to decompress the resulting image
     at	run-time.  This	allows for a significant reduction of size of disk im-
     age at the	expense	of some	CPU time required to decompress	the data each
     time it is	read.  The mkulzma utility works in two	phases:

     1.	  An infile image is split into	clusters; each cluster is compressed
	  using	liblzma.

     2.	  The resulting	set of compressed clusters along with headers that al-
	  low locating each individual cluster is written to the output	file.

     The options are:

     -o	outfile
	     Name of the output	file outfile.  The default is to use the input
	     name with the suffix .ulzma.

     -s	cluster_size
	     Split the image into clusters of cluster_size bytes, 16384	bytes
	     by	default.  The cluster_size should be a multiple	of 512 bytes.

     -v	     Display verbose messages.

     The compression ratio largely depends on the cluster size used.  For
     large cluster sizes (16K and higher), typical compression ratios are only
     1-2% less than those achieved with	lzma(1).  However, it should be	kept
     in	mind that larger cluster sizes lead to higher overhead in the
     geom_uncompress(4)	class, as the class has	to decompress the whole	clus-
     ter even if only a	few bytes from that cluster have to be read.

     The mkulzma utility inserts a short shell script at the beginning of the
     generated image, which makes it possible to "run" the image just like any
     other shell script.  The script tries to load the geom_uncompress(4)
     class if it is not	loaded,	configure the image as an md(4)	disk device
     using mdconfig(8),	and automatically mount	it using mount_cd9660(8) on
     the mount point provided as the first argument to the script.

     The mkulzma utility exits 0 on success, and >0 if an error	occurs.

     lzma(1), geom(4), geom_uncompress(4), md(4), mdconfig(8), mount_cd9660(8)

     Maxim Sobolev <>
     Aleksandr Rybalko <>

BSD				March 17, 2006				   BSD


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