Alan McKinnon wrote: > I would agree with both of you. In 15+ years I have never used debugfs > or dumpe2fs at all for any purpose. I would argue that that are barely > even suitable at LPIC-2 level, never mind LPIC-1.
My approach to debugfs in the LPIC-1 exams was always “Don't let anyone catch you futzing around with this on a file system that actually contains data”. I tell people that it exists and roughly what it does but I warn them off actually using it. dumpe2fs isn't really useful unless you're a file system developer, and I have no idea what that even does in the LPIC-1 exam. My personal debugfs success story dates back to before Linux was a thing. In those days I earned pocket money as an AIX administrator in the maths department of the university where I was studying, and we were good friends with the physics department sysadmins two stories above. Seems that one day one of the physics guys came down because he had just inadvertently deleted most of his thesis (or something of equal importance). I somehow contrived to use the AIX equivalent of debugfs to perturb the file system to a point where the AIX equivalent to fsck actually managed to get his files back, and from that point on I never needed to buy my own drinks when that guy was around. To this day I have no idea exactly what I was that I did, but it seems to have worked ;^) > On that topic, why are we still talking about 5% reserved for root in > 2017? IIRC that comes from the mid-90s when 5% was a small number of > inodes. Nowadays a 16TB fs is not uncommon, that 5% is 800G! An > excessive amount of essentially unused space just so root can juggle > some things around when the file system is "full" according to an > unpriviledged user. The reason for the 5% secret reserve is not just to give “root” some extra space to play with, but also to serve as extra elbow room for the file system to do its thing with defragmenting etc. A nearly-full ext?fs starts performing very poorly, and the 5% free space helps keep it in the safe zone. > I'm not sure I agree that xfs is worth a mention. If you need what it > can do, it's awesome, but it always seemed to me a specialized fs > outside of the normal and routine. Or maybe I just move in the wrong > circles. These days, XFS is a Red Hat thing in the way that btrfs is a SUSE thing. I suppose that if you're running with Red Hat people, XFS will be more important than btrfs and vice-versa. Anselm -- Anselm Lingnau · ans...@tuxcademy.org · https://www.tuxcademy.org Freie Schulungsmaterialien für Linux und Open-Source-Software Free Training Materials for Linux and Open-Source Software _______________________________________________ lpi-examdev mailing list lpi-examdev@lpi.org http://list.lpi.org/cgi-bin/mailman/listinfo/lpi-examdev
