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From: Zdenek Kabelac <zkabelac@redhat.com>
To: LVM general discussion and development <linux-lvm@redhat.com>,
	Gionatan Danti <g.danti@assyoma.it>
Cc: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
Subject: Re: [linux-lvm] lvm limitations
Date: Thu, 17 Sep 2020 21:32:07 +0200	[thread overview]
Message-ID: <39ab5393-7667-901c-f2a1-f25f40d057f2@redhat.com> (raw)
In-Reply-To: <cf779b76e25707b8ec3361f55318a1c7@assyoma.it>

Dne 16. 09. 20 v 0:26 Gionatan Danti napsal(a):
> Il 2020-09-15 23:47 Zdenek Kabelac ha scritto:
>> 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?

Hundreds should be 'fine' - but hundred thousands does mean the lvm2 metadata 
will reach GiB range - and this is definitely NOT fine ;)  - since you would 
probably need around way more RAM to even manages this ;) and I'm not talking
about some places with O^2 complexity in the lvm2 code...

The metadata format is simply not going to fly here...

Zdenek

  parent reply	other threads:[~2020-09-17 19:32 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
2020-09-17 19:17                     ` Zdenek Kabelac
2020-09-17 19:32                   ` Zdenek Kabelac [this message]
2020-09-14  6:03 Tomas Dalebjörk

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