linux-lvm.redhat.com archive mirror
 help / color / mirror / Atom feed
From: Alasdair G Kergon <agk@redhat.com>
To: Scott Moser <smoser@brickies.net>
Cc: linux-lvm@redhat.com
Subject: Re: [linux-lvm] Why does thinpool take 2*poolmetadatasize space?
Date: Tue, 20 Oct 2020 18:02:52 +0100	[thread overview]
Message-ID: <20201020170252.GA5698@agk-dp.fab.redhat.com> (raw)
In-Reply-To: <CAKxE60zw4MvD58ds-71yQdyxFkrujCm1XHNfbF=yYRqMRHF63w@mail.gmail.com>

On Tue, Oct 20, 2020 at 12:33:41PM -0400, Scott Moser wrote:
> When I create an lvmthinpool with size S and poolmetadatasize P,
> it reduces the available freespace by S+2P. I expected that to
> be S+P. Where did the extra poolmetadatasize get used?

So that you have sufficient disk space to store a second copy of it
if you need to perform any work on the metadata in future.

Recovery operations, for example, create a recovered copy in that
'spare' space then swap to use it leaving the space used by the
original metadata as the new 'spare'.

Alasdair

  reply	other threads:[~2020-10-20 17:02 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20 16:33 Scott Moser
2020-10-20 17:02 ` Alasdair G Kergon [this message]
2020-10-20 18:02 ` Zdenek Kabelac

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201020170252.GA5698@agk-dp.fab.redhat.com \
    --to=agk@redhat.com \
    --cc=linux-lvm@redhat.com \
    --cc=smoser@brickies.net \
    --subject='Re: [linux-lvm] Why does thinpool take 2*poolmetadatasize space?' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).