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From: Ede Wolf <>
To: LVM general discussion and development <>
Subject: Re: [linux-lvm] thinpool metadata got way too large, how to handle?
Date: Wed, 8 Jan 2020 15:23:19 +0100	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Thanks VERY much for your help, I'll try this out, it just takes a 
couple of days to resize the raid after having added a new drive. Or 
I'll organise a seperate one for the metadata. Maybe a good idea.

I've completely missed the -o switch for thin_repair.

Bare with me, I'll definately try this out, after having checked the 
repair version, and report back.


P.S. in case it matters or helps, these are the steps from the bash 
history I've taken once the resync of the mdraid with the added 3TB 
drive had completed and that led to the somewhat enlarged metadata lv:

lvextend -l 80%VG VG_Raid6/ThinPoolRaid6
pvresize /dev/md2
lvextend -l 80%VG VG_Raid6/ThinPoolRaid6
lvextend -l 100%VG VG_Raid6/ThinPoolRaid6
lvextend -l +100%VG VG_Raid6/ThinPoolRaid6

As you can see, initially I've forgott about pvresize. And the to me 
somewhat counter intuitive way having to specify "+" for an absolute 
value had made me use lvextend multiple times.
No complaint, just for the sake of completeness, even though I left out 
all the pv- or lvdisplay commands.
But I never touched the metadatapool directly.

Am 08.01.20 um 12:29 schrieb Zdenek Kabelac:
> Dne 02. 01. 20 v 19:19 Ede Wolf napsal(a):
>> Hello,
>> While having tried to extend my thinpool LV, after the underlying md
>> raid had been enlarged, somehow the metadata LV has gotten all the
>> free space and now is 2,2 TB in size. Space, that is obviously now
>> missing for the thinpool data LV, where it should have gone in first
>> place.
> Hi
> I might guess you were affected by bug in 'percent' resize logic,
> that has been possibly addressed by this upstream patch:
> Although your observed result of having 2.2TB metadata size looks 
> strange - it should not normally extend the size of LV to this extreme 
> dimension - unless we miss some more context here.
>> And since reducing the metadata LV of the thinpool is not possible, I
>> am now wondering, what options I may have to reclaim the space for its
>> intended purpose?
> You can reduce the size of metadata this way:
> (It might be in future automated somehow in LV - as there
> are further enhancements on thin tools which can make 'reduction' of 
> -tmeta size a 'wanted' feature)
> For now you need to active thin-pool metadata in read-only mode (so 
> called 'component activation' (which means no thin-pool nor any thinLV 
> is active - only _tmeta LV and it's supported with some recent versions 
> of lvm)
> (For older version of lvm2 - you would need to first 'swap-out' existing 
> metadata to get access to them)
> Then create some 15GiB sized LV� (used as your rightly sized new metadata)
> Then run from 2.2T -> 15G LV:
>  �thin_repair� -i /dev/vg/pool_tmeta -o /dev/vg/newtmeta
> This might take some time (depending on CPU speed and disk speed) - and 
> also be sure you have� >= 0.8.5 of thin_repair tool (do not try this 
> with older version...)
> Once this thin_repair is finished - swap in your new tmeta LV:
> lvconvert --thinpool vg/pool --poolmetadata vg/newtmeta
> And now try to active your thinLVs and check all works.
> If all is ok - then you can 'lvremove' now unused� 2.2TiB LV� (with the 
> name newtmeta -� as� LV content has been swapped - just check with 'lvs 
> -a' output
> the sizes are whan you are expecting.
> If you are unsure with any step - consult further here your issue please
> (better before you do some irreversible mistake).
>> Currently I have no extends left - all eaten up by the metadata LV, but
>> I would be able to add another drive to enlargen the md raid and
>> therefore the PV/VG
> You will certainly need at least temporarily some extra space of ~15GiB.
> You can try with i.e. USB attached drive - you add such PV into VG 
> (vgextend)
> You then create your LV for new tmeta (as described above)
> Once you are happy with 'repaired'� thin-pool and your 2.2TiB LV is 
> removed,
> then you just 'pvmove' your new tmeta into VG on 'old' storage,
> And finally you will simply vgreduce your (now again) unused USB drive.
> Hopefully this will work well.
> Regards
> Zdenek

  reply	other threads:[~2020-01-08 14:23 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-02 18:19 [linux-lvm] thinpool metadata got way too large, how to handle? Ede Wolf
2020-01-08 11:29 ` Zdenek Kabelac
2020-01-08 14:23   ` Ede Wolf [this message]
2020-01-10 16:30   ` Ede Wolf
2020-01-10 16:51     ` Zdenek Kabelac

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