Re: [Testbed-admins] CentOS image

[Leigh Stoller <stoller@flux.utah.edu>]

> We went ahead and install centos and made an image but the imagezip
> tool gave an error and to use raw compression (-R2 which did worked)
> we haven't reloaded the image yet elsewhere to test it though....
> is it bad to use the raw compression option?  How is option R1
> different from R2?  and are there more Rx options?

Mike usually answers frisbee questions, but he is on vacation. So,
I'll step in and spread rumors and false information. :-)

The image tool tries to use filesystem aware compression; thats a
fancy way of saying it knows how to read the free block lists and
knows not to bother with them. This reduces the size of the resulting
file to a fraction of what it would otherwise be, and it speeds up the
time it takes to lay the image back down, by many times.

imagezip can do this for BSD, Linux, and Windows file systems.  When
imagezip does not know how to deal with a file system it used "raw"
compression, which treats disk a big block of stuff to compress with
zlib. Workable, just really slow.

Okay, so centos is based on Linux, correct? Do you know if centos uses
something other then ext2/3 or perhaps has its own magic number that
it sticks into the MBR.

Lbs