Hmmm, ok, i been taking a look at the settings i was using in iris 2.93 and below for PS3 games in JB format in dev_hdd0... and taking a read at the documentation written by estwald in the official thread here:
https://www.elotrolado.net/wiki/Iris_Manager
Im writing this for the record, because is tricky to understand, and as a reminder for myself because i use to forget the details... you know every user decides which settings fits for his setup and you start using that ones always and forget at the details, also 99,9% users of the PS3 backup managers doesnt knows exactly what the backup manager settings are doing (me included) :P
I will update this post later (so take another read at it tomorrow or whatever) by copypasting parts of the documentation written by estwald in spanish (together with a english translation)
In iris 2.93...
start (global options) ---> tools --->
--With BDVD controller (this is used to make backups from real discs inserted in the drive)
--Without BDVD controller (this was used by people with damaged/unmarried BD daughterboard... but this mounting method became obsolete, right ?)
--disc-less payload (this is described by estwald as "the jewell of the crown")
Additionally, for the games in PS3 JB format in internal dev_hdd0 i always used this:
select (game options) ---> config game --->
--requires disc = NO
--direct boot = NO
--extern EBOOT.BIN = Off
--BD Emu = LIBFS
--Ext /dev_hdd0/game = Off
In short, i was using "discless payload" + "libfs"... and additionally, i always had the optional .sprx modules libfs and explore_plugin patched
I knew libfs was used when booting the game this way (obviouslly, is mentioned in a setting), but the reason why i always used the libfs patch is because all my games are in internal hdd (never in usb with a few exceptions)
The patch in libfs improves the compatibility in internall hdd (is a "must use" if your game is PS3 JB in internal)... but it "breaks" the compatibility if the game is PS3 JB in external (so is a "never use it" if your game is PS3 JB in external)
Regarding the explore_plugin patched module... well, i always had it patched "just incase" because there are a couple of sentences written by estwald that are not clear if is used in this boot mode