[Fedora-livecd-list] RFC- improving livecd installer efficiency

[Greg Dekoenigsberg]

I see someone besides me uses mailing lists to keep public notes for 
themselves to remember later.  :)

--g

On Tue, 10 Jul 2007, Douglas McClendon wrote:

> Douglas McClendon wrote:
>> Douglas McClendon wrote:
>>> Question:  Does the current livecd installer inefficiently write lots of 
>>> 0's to the destination drive that it doesn't need to?
>>> 
>>> I think it might.  The os.img on the F7 livecd is a 4G sparse file with 
>>> about 2.3G of data.  Anaconda's livecdcopy backend uses python's 
>>> os.read/write.  I would guess that that means that 4G of data is getting 
>>> written, when theoretically only 2.3G needs to.
>>> 
>>> The solution that comes to mind is this-
>>> 
>>> in livecd-tools, create the os.img as a 7G (or 700G??) sparse file. 
>>> Basically just way big.  Then take care to make the ext3fs be the exact 
>>> correct size for the data (i.e. 2.3G).  Then, in the initramfs, just after 
>>> mounting it (after snapshotting it), do a resize2fs to 7G (or 700G).
>> 
>> To clarify a bit- Clearly the resize2fs should probably happen during boot 
>> (long after initramfs).  No need to bloat the initramfs with resize2fs.
>> 
>
> Yeah, I really gotta stop posting when I'm sleep deprived.  Clearly in 
> initramfs you have access to sysroot thus no bloat.
>
> and...
>
>> Also, the mechanism that comes to mind for the ext3fs creation is this-
>> 
>> Take the existing image built as is, but after final install, resize2fs it 
>> to the smallest possible (nearly), then truncate the file, then do the dd 
>> seek trick to re-sparsify it vastly larger.
>> 
>> Or perhaps just throw in an entire extra tarcopy of the system to a new fs 
>> image file created the exact right size from the beginning.  This is more 
>> work, but will possibly save space on any files that got created and 
>> deleted during the installation process.
>> 
>
> clearly the resize2fs to minimal will take care of the created/deleted issue.
>
> -dmc
>
> --
> Fedora-livecd-list mailing list
> Fedora-livecd-list at redhat.com
> https://www.redhat.com/mailman/listinfo/fedora-livecd-list
>

-- 
Greg DeKoenigsberg
Community Development Manager
Red Hat, Inc. :: 1-919-754-4255
"To whomsoever much hath been given...
...from him much shall be asked"