Re: [gentoo-user] Safeguarding strategies against SSD data loss

[Pandu Poluan <pandu@poluan.info>]

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On Oct 28, 2014 12:31 AM, "Rich Freeman" <rich0@gentoo.org> wrote:
>
> On Mon, Oct 27, 2014 at 12:52 PM, Pandu Poluan <pandu@poluan.info> wrote:
> >
> > ZoL (ZFS on Linux) nowadays is implemented using DKMS instead of FUSE,
thus
> > running in kernelspace, and (relatively) easier to put into an
initramfs.
>
> Sorry about that.  I should have known that, but for some reason I got
> that memory crossed in my brain...  :)
>
> > vdevs can grow, but they can't (yet) shrink.
>
> Can you point to any docs on that, including any limitations/etc?  The
> inability to expand raid-z the way you can do so with mdadm was one of
> the big things that has been keeping me away from zfs.  I understand
> that it isn't so important when you're dealing with large numbers of
> disks (backblaze's storage pods come to mind), but when you have only
> a few disks being able to manipulate them one at a time is very
> useful.  Growing is the more likely use case than shrinking.  Then
> again, at some point if you want to replace smaller drives with larger
> ones you might want a way to remove drives from a vdev.
>

First, you need to set your pool to "autoexpand=on".

Then, one by one, you offline a disk within the vdev and replace it with a
larger one. After all disks have been replaced, do a scrub, and ZFS will
automagically enlarge the vdev.

If you're not using whole disks as ZFS, then s/replace with larger/enlarge
the partition/.

Rgds,
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