Thanks to anyone that can help me out of this daunting situation !
My PC has 2 hard drives, all filesystem but swap are formatted in ext4 :
-One SSD where is located a Ubuntu 14.04 partition (sda3) that I have been using since 2014 [sda2 was a swap partition that I deleted when I learnt that shouldn't go on SSD and (sda1) must be some kind of boot for ubuntu, I forgot]
-One HDD with 3 partition : (sdb1) which I use for storing all my personal files and which I always mount on /data (in order to avoid mixing /home configuration files and my personal files) + (sdb3) where I have installed last week a fresh Manjaro 16.10 Xfce + (sdb2) swap
The process of installing and configuring my favorite packages took me about 3 days during which everything was going perfectly fine. Appart from a driver for my Samsung clx-3185 printer which was downloaded from Samsung website at day 1, all the installs and remove packages was performed with pacman and pamac. Powered off and back on a number of times without problems.
Yesterday evening , noticed that Firefox was not opening and decided to power off and back on. That’s when problems started to appear in the below order :
Screen blocked at the splash screen “Manjaro ….” --> used the Pc power off button to leave and reboot without quiet splash
At reboot : system advising very quickly on boot that filesystem was corrupted and needed a fsck without the –p or –a option "unexpected inconsistency"
Rebooted on the Ubuntu 14.04 to perform the fsck which found numerous disk problems (asked to extend lost+found at some point)
Gave on other try at Manjaro which went a bit further this time until mouse and blinking cursor seemed to enter in an endless loop on the screen, tried ctrl+alt+F1 and read something like
failed command : READ DMA EXT
blk_update_request : I/O error, dev/sdb, sector 1844813048
Went back an other time to Ubuntu and performed an other fsck which fixed a different set of problems (some looked similar but others was definitely new)
Just to be sure ran fsck an other time but with the –p option and it said that the filesystem was clean (lost+found seems heavily populated but folders on the root of the tree are there)
After reading the different posts, I think I should now use mhwd-chroot as explained in https://archived.forum.manjaro.org/t/how-to-save-your-manjaro-installation-when-it-breaks/75 to try and repair the whole thing but two questions come to my mind :
1 - What to do once I will have successfulyy chrooted the system ? Is there a command to check what is broken or to re-install every single package of my system ?
2 - No idea if the problem is coming from hard or soft, smartctl says my disk power on time is abt 30 000 hours but most of it being idle as I never stop the PC but wondering why did it happen just after installing Manjaro, is this something frequent here ?
thank you very much, here below some additional infos on my system :
sdb = Western Digital Scorpio Blue Serial ATA (AF)
cpu = Intel(R) Atom(TM) CPU D525 @ 1.80GHz - cores=2 enabledcores=2 threads=4