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#1 2018-10-13 18:00:50

Registered: 2018-01-23
Posts: 21  

HOWTO: Bypass the 4GB filesize limit in Refractasnapshot

Hello Everyone

I finally found a way to make to make ISO snapshots that can be larger than 4GB.
I had this problem for a long time that i would get an Error during the snapshot progress because i have a lot of packages installed on my system.
I know some folks have had the same problem so i thought i'd share the solution to this.

For this to work one has to modify the xorriso command in /usr/bin/refractasnapshot,
my code may differ from your version, the important thing is to add the -iso-level 3 option

xorriso -as mkisofs -r -J -joliet-long -l -iso-level 3 -isohybrid-mbr /usr/lib/ISOLINUX/isohdpfx.bin -partition_offset 16 -V "$volid"  -b isolinux/isolinux.bin -c isolinux/ -no-emul-boot -boot-load-size 4 -boot-info-table -o "$iso_dir"/"$filename" live/ 

and thats all
i now have a 4.2 GB large ISO file smile


#2 2018-10-21 17:00:18

Registered: 2016-11-25
Posts: 977  

Re: HOWTO: Bypass the 4GB filesize limit in Refractasnapshot

Thanks! Added to my TODO notes. You just saved me from writing a bunch of code to make a live-usb from a snapshot work directory for cases where the iso is too big.


#3 2018-10-22 01:22:17

Registered: 2016-11-25
Posts: 1,486  

Re: HOWTO: Bypass the 4GB filesize limit in Refractasnapshot

Well . . .  I have good news to report.  I have been unable to create an iso with refractasnapshot for a very long time despite excluding ALL of my /home directory because the iso were always too big.  So fsmithred and I decided to test your discovery.  He instructed me to change line 1010 from this:

 xorriso -as mkisofs -r -J -joliet-long -l ${isohybrid_opt} \

To this:

 xorriso -as mkisofs -r -J -joliet-long -l ${isohybrid_opt} -iso-level 3 \

It took refracta-snapshot-gui a very long time to copy and squash the files since I had deleted the work directory but eventually it finished with a 4.9GB iso.

Then it was time to try it in qemu.  I was delighted to see the boot process working as usual!!!

Now I need to redo the exclude list to include a basic home structure and perhaps delete a few things elsewhere starting with avahi.

I am overjoyed that I can now use refractasnapshot again.   And this is also a milestone improvement for refracta!  Thank you, thank you alphalpha!!!


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