Re: how to best segment a big block device in resizeable btrfs filesystems?

[Marc MERLIN <marc@merlins.org>]

On Tue, Jul 03, 2018 at 04:26:37AM +0000, Paul Jones wrote:
> I don't have any experience with this, but since it's the internet let me tell you how I'd do it anyway 😝

That's the spirit :)

> raid5
> dm-crypt
> lvm (using thin provisioning + cache)
> btrfs
> 
> The cache mode on lvm requires you to set up all your volumes first, then
> add caching to those volumes last. If you need to modify the volume then
> you have to remove the cache, make your changes, then re-add the cache. It
> sounds like a pain, but having the cache separate from the data is quite
> handy.

I'm ok enough with that.

> Given you are running a backup server I don't think the cache would
> really do much unless you enable writeback mode. If you can split up your
> filesystem a bit to the point that btrfs check doesn't OOM that will
> seriously help performance as well. Rsync might be feasible again.

I'm a bit warry of write caching with the issues I've had. I may do
write-through, but not writeback :)

But caching helps indeed for my older filesystems that are still backed up
via rsync because the source fs is ext4 and not btrfs.

Thanks for the suggestions
Marc
-- 
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Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/