From: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
To: Gionatan Danti <g.danti@assyoma.it>
Cc: LVM general discussion and development <linux-lvm@redhat.com>,
Zdenek Kabelac <zkabelac@redhat.com>
Subject: Re: [linux-lvm] lvm limitations
Date: Wed, 16 Sep 2020 06:58:50 +0200 [thread overview]
Message-ID: <E99B2EFD-42A3-4EAA-81C5-E04325569E8D@gmail.com> (raw)
In-Reply-To: <cf779b76e25707b8ec3361f55318a1c7@assyoma.it>
just curious about this:
> 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....
would that mean that one single thin-pool can maximum hold 16GiB/16 nr of blocks?
and how about if LVM2 uses VDO as backend, are there more limitations that I need to consider there that are not reflected here
Sent from my iPhone
> On 16 Sep 2020, at 00:26, Gionatan Danti <g.danti@assyoma.it> wrote:
>
> Il 2020-09-15 23:47 Zdenek Kabelac ha scritto:
>> You likely don't need such amount of 'snapshots' and you will need to
>> implement something to remove snapshot without need, so i.e. after a
>> day you will keep maybe 'every-4-hour' and after couple days maybe
>> only a day-level snapshot. After a month per-week and so one.
>
> Agree. "Snapshot-thinning" is an essential part of snapshot management.
>
>> Speaking of thin volumes - there can be at most 2^24 thin devices
>> (this is hard limit you've ask for ;)) - but you have only ~16GiB of
>> metadata to store all of them - which gives you ~1KiB of data per such
>> volume -
>> quite frankly this is not too much - unless as said - your volumes
>> are not changed at all - but then why you would be building all this...
>> That all said - if you really need that intensive amount of snapshoting,
>> lvm2 is likely not for you - and you will need to build something on your own,
>> as you will need way more efficient and 'targeted' solution for your purpose.
>
> Thinvols are not activated by default - this means it should be not a big problem managing some hundreds of them, as the OP ask. Or am I missing something?
>
> Regards.
>
> --
> 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:[~2020-09-16 4:58 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
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 [this message]
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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