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

[Douglas McClendon]

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