On 2017-06-22 05:37, Shyam Prasad N wrote:
Hi,
I'm planning to use the btrfs-convert tool to convert production data
in ext4 filesystem into btrfs.
What is the stability status of this feature?
As per the below link, this tool is not in frequent use in latest linux kernels.
https://btrfs.wiki.kernel.org/index.php/Conversion_from_Ext3
Can I know the reason why? Is it because most existing ext4
filesystems are already converted?
Is this tool supported, at least? Can I use this tool as a part of
software upgrade to change the data filesystem to btrfs?
Yes, it's supported, but unless you need the ability to switch back as
quickly as possible, you are almost certainly better off restoring data
from a fresh backup onto a new BTRFS filesystem than you are converting
it in-place. I have heard of no currently extant bugs in btrfs-convert,
but they usually don't show up immediately, and even if there are no
bugs, you still end up with a very sub-optimal on-device layout which
isn't even completely fixed by deleting the ext4 metadata and
re-balancing, and that will in turn hurt performance somewhat. At a
minimum, I would suggest running e4defrag over the whole filesystem
prior to converting, as that will at least reduce the degree of
fragmentation you start with.
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