Re: btrfs problems on new file system

[covici@ccs.covici.com]

Chris Murphy <lists@colorremedies.com> wrote:

> On Sat, Dec 26, 2015 at 4:38 AM,  <covici@ccs.covici.com> wrote:
> > Duncan <1i5t5.duncan@cox.net> wrote:
> >
> >> covici posted on Sat, 26 Dec 2015 02:29:11 -0500 as excerpted:
> >>
> >> > Chris Murphy <lists@colorremedies.com> wrote:
> >> >
> >> >> If you can post the entire dmesg somewhere that'd be useful. MUAs tend
> >> >> to wrap that text and make it unreadable on list. I think the problems
> >> >> with your volume happened before the messages, but it's hard to say.
> >> >> Also, a generation of nearly 5000 is not that new?
> >> >
> >> > The file system was only a few days old.  It was on an lvm volume group
> >> > which consisted of two ssd drives, so I am not sure what you are saying
> >> > about lvm cache -- how could I do anything different?
> >> >
> >> >> On another thread someone said you probably need to specify the device
> >> >> to mount when using Btrfs and lvmcache? And the device to specify is
> >> >> the combined HDD+SSD logical device, for lvmcache that's the "cache
> >> >> LV", which is the OriginLV + CachePoolLV. If Btrfs decides to mount the
> >> >> origin, it can result in corruption.
> >> >
> >> > See above.
> >>
> >> I think he mixed up two threads and thought you were running lvm-cache,
> >> not just regular lvm, which should be good unless you're exposing lvm
> >> snapshots and thus letting btrfs see multiple supposed UUIDs that aren't
> >> actually universal.  Since btrfs is multi-device and uses the UUID to
> >> track which devices belong to it (because they're _supposed_ to be
> >> universally unique, it's even in the _name_!), if it sees the same UUID
> >> it'll consider it part of the same filesystem, thus potentially causing
> >> corruption if it's a snapshot or something that's not actually supposed
> >> to be part of the (current) filesystem.
> >
> > I found a few more log entries, perhaps these may be helpful to track
> > this down, or maybe prevent the filesystem from going read-only.
> 
> No, you need to post the entire dmesg. The "cut here" part is maybe
> useful for a developer diagnosing Btrfs's response to the problem, but
> the problem, or the pre-problem, happened before this.

It would be a 20meg file, if I were to post the whole file.  but I can
tell you, no hardware errors at any time.


-- 
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