From: Gionatan Danti <g.danti@assyoma.it>
To: Zdenek Kabelac <zkabelac@redhat.com>
Cc: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>,
"LVM general discussion and development" <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] lvm limitations
Date: Tue, 01 Sep 2020 15:21:34 +0200 [thread overview]
Message-ID: <8a3a46b57b9264039885e8e7401e9dbd@assyoma.it> (raw)
In-Reply-To: <bf377813-8600-865a-71b7-dd6873113f46@redhat.com>
Il 2020-08-30 21:30 Zdenek Kabelac ha scritto:
> Hi
>
> Lvm2 has only ascii metadata (so basically what is stored in
> /etc/lvm/archive is the same as in PV header metadata area -
> just without spaces and some comments)
>
> And while this is great for manual recovery, it's not
> very efficient in storing larger number of LVs - there basically
> some sort of DB attemp would likely be needed.
>
> So far however there was no real worthy use case - so safety
> for recovery scenarios wins ATM.
Yes, I agree.
> Thin - just like any other LV takes some 'space' - so if you want
> to go with higher amount - you need to specify bigger metadata areas
> to be able to store such large lvm2 metadata.
>
> There is probably not a big issue with lots of thin LVs in thin-pool as
> long
> as user doesn't need to have them active at the same time. Due to a
> nature of
> kernel metadata handling, the larger amount of active thin LVs from
> the same thin-pool v1 may start to compete for the locking when
> allocating thin pool chunks thus killing performance - so here is
> rather better to stay in some 'tens' of actively provisioning thin
> volumes when the 'performance' is factor.
Interesting.
> Worth to note there is fixed strict limit of the ~16GiB maximum
> thin-pool kernel metadata size - which surely can be exhausted -
> mapping holds info about bTree mappings and sharing chunks between
> devices....
Yes, I know about this specific limitation.
Thanks.
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8
next prev parent reply other threads:[~2020-09-01 13:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-29 23:25 [linux-lvm] lvm limitations Tomas Dalebjörk
2020-08-30 17:33 ` Zdenek Kabelac
2020-08-30 18:01 ` Gionatan Danti
2020-08-30 19:30 ` Zdenek Kabelac
2020-09-01 13:21 ` Gionatan Danti [this message]
2020-09-15 19:16 ` Tomas Dalebjörk
2020-09-15 20:08 ` Zdenek Kabelac
2020-09-15 21:24 ` Tomas Dalebjörk
2020-09-15 21:30 ` Stuart D Gathman
2020-09-15 22:24 ` Gionatan Danti
2020-09-15 21:47 ` Zdenek Kabelac
2020-09-15 22:26 ` Gionatan Danti
2020-09-16 4:25 ` Tomas Dalebjörk
2020-09-17 19:24 ` Zdenek Kabelac
2020-09-16 4:31 ` Tomas Dalebjörk
2020-09-16 4:58 ` Tomas Dalebjörk
2020-09-17 19:17 ` Zdenek Kabelac
2020-09-17 19:32 ` Zdenek Kabelac
2020-09-14 6:03 Tomas Dalebjörk
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