Re: 800 GByte free, but "no space left"

[Hugo Mills <hugo-lkml@carfax.org.uk>]

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On Mon, Dec 06, 2010 at 01:56:31AM -0800, Brian Rogers wrote:
> On 12/05/2010 10:26 AM, Helmut Hullen wrote:
> >>So, by far the simplest solution would be to re-create your file
> >>system with "single" mode,
> >Can I add or delete hard disks/partitions to the two devices/partitions
> >in your example?
> 
> You can add, but you'll want to avoid deleting, balancing, and
> shrinking. From my testing, any of these operations will convert the
> chunks they relocate to raid0. Then, once you have any raid0 data,
> btrfs will want to allocate all new chunks as raid0 and you'll have
> the unusable space problem again.

   That's a known bug. Josef even posted a patch for it (but it's
apparently not doing the right thing yet).

> >I've studied the man page and the Wiki but didn't find any help.
> >
> >And in my special case I have to add at least yearly new disks and from
> >time to time remove the smallest disks from this bundle.
> 
> With the current state of btrfs, you could do this as long as you
> never reduce the total number of disks. When you want to replace an
> old disk with a new one, just go around btrfs: take the filesystem
> offline and copy the old disk's partition into a full-sized
> partition on the new disk. Then remove the old disk and bring the
> filesystem online again.
> 
> It will remember the old size at first, but that can be fixed with
> 
> btrfs filesystem resize <devid>:max <path>

   This doesn't work on multi-volume filesystems (yet).

   Hugo.

-- 
=== Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk ===
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