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From: Zdenek Kabelac <zkabelac@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>,
	Scott Moser <smoser@brickies.net>
Subject: Re: [linux-lvm] Why does thinpool take 2*poolmetadatasize space?
Date: Tue, 20 Oct 2020 20:02:04 +0200	[thread overview]
Message-ID: <69aeb37e-ee16-6bdb-0ae3-456b83c99289@redhat.com> (raw)
In-Reply-To: <CAKxE60zw4MvD58ds-71yQdyxFkrujCm1XHNfbF=yYRqMRHF63w@mail.gmail.com>

Dne 20. 10. 20 v 18:33 Scott Moser napsal(a):
> 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?
> 
> See below for example.
> before lvcreate we had 255868 free, after we had 254588.
> The difference is 1280.  (1024 + 2*128).
> 


lvm2 preallocated hidden _pmspare volume which has the size of
biggest metadata LV in a VG.

Such LV is used for automated 'lvconvert --repair'.

If you don't want this LV to be created you can add

--poolmetadataspare y|n

but in this case you are fully in your own to figure out,
where to take the space for repaired metadata.

You can also at any time lvremove _pmspare LV if necessary.

Regards

Zdenek

      parent reply	other threads:[~2020-10-20 18:02 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
2020-10-20 18:02 ` Zdenek Kabelac [this message]

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