[Fedora-livecd-list] [PATCH 6/7] anaconda: liveinst.sh: support turboLiveInst/genMinInstDelta

[Douglas McClendon]

Jeremy Katz wrote:
> On Tue, 2007-09-18 at 15:48 -0500, Douglas McClendon wrote:
>> Jeremy Katz wrote:
>>> Although then the other question is what to do when we're not squashed.
>>> Do we just then want to put it on the ext3fs?
>> Here is the heart of something I think I mentioned that was wrong a long 
>> time ago.  I mentioned something like "osmin can't live on the squashfs 
>> for obvious reasons".  Actually, the truth is "osmin can't live on the 
>> ext3 for obvious reasons".  And the subtle error there kept the idea out 
>> of my mind.
> 
> The simple answer is just don't do the osmin bits if you're not using
> squashfs.  Given that it's a debug option only, that's probably not
> crazy

Thats the answer to...?  to not having the --ignore-deleted and 
--turbo-liveinst options?  I agree.

One big problem with skip-compression as is, is that when the ext3 image 
lives natively on the iso9660

1) iso9660 does not(?) support sparse files, so currently with your 4.0G 
ext3 image containing 2.2G of data, you have to store 4.0G data.

2) iso9660 sortof has 2G filesize limits (apparently 2G->4.2G might 
work, and 4.2G->8TB could theoretically work...)

One possible solution for 1), might be to house the sparse file in a 
container filesystem (either squashfs, or a properly minimized ext2).

One possible solution for 2) would be to split the container filesystem 
(1.75G chunks?), and then associate a loop device with each, and use a 
devicemapper linear device to stitch them all together into one big image.

> 
>> But...
>>
>> It occurs to me that because of what anaconda is doing, I.e. a big 2G 
>> dd, it may actually be problematic that squashfs pages out(?) the osmin 
>> data, and needs to reread it from cdrom often, thus screwing up a nice 
>> big linear seek-free read.
> 
> Famous last words are "it shouldn't really make a difference" ;)

Ok, now I think I've _really_ got it figured out-

1) at livecd creator time, put the osmin in it's own squashfs.  I just 
tried this, and it produces a 12kb squashfs image.

2) now, at initramfs time, copy the squashfs image to tmpfs, loop mount 
it, associate the loop118 device with the file inside that squashfs, and 
then build the devicemapper minimized device

*NOW*, osmin once again only lives in tmpfs, *AND* ram is only used for 
its 1.2M of data during anaconda install time.

-dmc