#2210 Issue `closed`: Creating bootable USB from ReaR ISO¶

Labels: enhancement, documentation, no-issue-activity

adatum opened issue at 2019-08-13 04:04:¶

ReaR 2.4

The ISO image created by ReaR is not a hybrid and therefore does not lend itself to creating a bootable USB from the ISO. With such an image "burned" to a USB device, the system does not boot from it.

Fortunately the solution is trivial: isohybrid [ISO] converts it to a hybrid ISO. Option flag -u or --uefi makes it UEFI bootable.

Would you consider creating hybrid ISOs by default, and/or mentioning isohybrid in the documentation?

I prefer to create an ISO and store it with backups. However, I will almost certainly prefer using a bootable USB for any recovery. Storing ISOs means I do not need to tie up USBs with recovery images, instead creating it (the USB, not the mkrescue image of course.. ) when needed.

A workaround is to do something like:

rear mkrescue && isohybrid -u /var/lib/rear/output/rear-$(hostname).iso

jsmeix commented at 2019-08-16 09:47:¶

@adatum
thank you for the exact workaround command that makes things work for you.

I think it should not be too complicated to add a new ISOHYBRID config variable
to default.conf so that the user can specify whether or not to get a hybrid ISO
(we will have to see if a hybrid ISO by default could cause whatever unexpected
regressions in this or that special cases).

By the way:
If you used "rear mkbackup" (instead of "rear mkrescue") you could have
mis-used POST_BACKUP_SCRIPT to call isohybrid, see in default.conf
https://github.com/rear/rear/blob/master/usr/share/rear/conf/default.conf#L2769

adatum commented at 2019-08-18 02:43:¶

No problem, hopefully it's helpful. Fortunately there are many easy solutions.

A config variable could be handy. I agree it's probably best not to change the default behavior. I'm not sure if a hybrid ISO would present any backwards compatibility concerns compared to a standard ISO.

POST_BACKUP_SCRIPT could be good for someone using ReaR for backups. (I'm not.)

Instead I'm using Borg for backups and borgmatic for automation. borgmatic has pre- and post-operation hooks for running shell commands. Right now, I have /usr/sbin/rear checklayout || /usr/sbin/rear mkrescue && isohybrid -u /var/lib/rear/output/rear-$(hostname).iso as a pre-backup hook.