[gentoo-user] btrfs strategies (wasHard drive noise)

[covici@ccs.covici.com]

covici@ccs.covici.com wrote:

> Rich Freeman <rich0@gentoo.org> wrote:
> 
> > On Sat, Dec 19, 2015 at 2:56 AM,  <covici@ccs.covici.com> wrote:
> > >
> > > I was never able to get either zfs or btrfs to work correctly, zfs was
> > > very vulnerable -- I forgot to export a zfs on a usb drive and got an
> > > enless loop of processes untill I rebooted.  Btrfs never did work for
> > > me, I created a pool,  copied my root file system, usr and var into
> > > ssubvolumes, and copied my files, but when I would boot into it,
> > > everything was messed up, processes thought files were missing, very
> > > strange.  So, how did you set up either one of those -- I would love to
> > > use it because I have ssds and I don't want to rely on their firmware
> > > either.
> > 
> > Well, I don't have much personal experience with zfs, but the ZFS on
> > Linux lead is a Gentoo dev, so you're in good company there all the
> > same.  I personally use btrfs.
> > 
> > The obvious caveat is that it is still relatively experimental, and
> > raid5/6 is VERY experimental.  I plan to convert to raid5/6 at a
> > future date but am staying away from it for now (and a selling point
> > of btrfs is that reshaping in-place is easy).
> > 
> > I can't really vouch for what went wrong with your migration.  It
> > could be anything from a failure to preserve all your file attributes
> > to something with btrfs itself or your bootloader config/etc.  It
> > isn't hard to do a new install in btrfs though, and you can always
> > mess with it in a VM, or even mess with doing migrations in a VM.
> > 
> > My btrfs install notes are at:
> > https://docs.google.com/document/d/1VJlJyYLTZScta9a81xgKOIBjYsG3_VfxxmUSxG23Uxg/edit?usp=sharing
> > (I still plan to merge this stuff into the handbook.  Maybe a good
> > holiday project...  Oh, and if it isn't already obvious anybody can
> > add comments and half this list seems to have already done so.)
> > 
> > Oh, for a boot image I tend to use system rescue CD since it has all
> > the necessary userspace and is gentoo-based (and you can always emerge
> > --sync and install whatever you need inside it).  I tend to use the
> > alternate kernel since it is newer, and with btrfs newer tends to be
> > better.  In production I'm currently on 3.18 eyeing an upgrade to 4.1.
> > I tend to stay on the latest longterm, but not when they are first
> > declared as longterm.  That seems to be the sweet spot for getting
> > btrfs features and bugfixes, but not getting as many of the
> > regressions.  I use grub2/dracut to boot, and that is in my guide.
> > 
> > If you follow those notes for a stage3 install it should "just work."
> > If you want to mess around I suggest just doing a vanilla install on a
> > VM once to validate that it works for you and then tweak from a
> > position of strength.
> 
> Thanks.  I will check out your notes and figure out something -- it was
> definitely strange.  I have a vm I can play with -- its older, but I can
> bring it up to date and see what happens.
> 
> Thanks again.

One thing I was thinking of -- since I like separate file systems for
each major directory i.e. separate /usr, /var, /home, /tmp and even
/var/tmp/portage, I thought I would make btrfs file systems using lvm.
The advantage is that I use lvm already, so this would be easy for me to
do and safer in case one of them goes south and easier to control  space
allocation.  The only disadvantage I can see is if its a performance
hit, does anyone have any knowledge of that is true?

-- 
Your life is like a penny.  You're going to lose it.  The question is:
How do
you spend it?

         John Covici
         covici@ccs.covici.com