From: Gionatan Danti <g.danti@assyoma.it>
To: Zdenek Kabelac <zdenek.kabelac@gmail.com>
Cc: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] lvm-vdo, snapshots and cache
Date: Wed, 16 Nov 2022 15:38:34 +0100 [thread overview]
Message-ID: <99746334610331ae0f7cca166649fdd0@assyoma.it> (raw)
In-Reply-To: <8865e8e7-fede-d904-8970-771afae19504@gmail.com>
Il 2022-11-16 11:50 Zdenek Kabelac ha scritto:
> Well - as said - vg on vg is basically equivalent of the original LV
> on top of VDO manager.
Hi Zdenek,
it seems clunkier to manage two nested VG/LV if you ask me.
> But still these fast snapshot do not solve you a problem of double
> out-of-space fault.
Yeah, but available space requires constant monitor even when dealing
with lvmthin.
> It's good for experimenting - but I'd not suggest to use this setup.
In RHEL7 it was specifically supported - see here[1]:
"As a general rule, you should place certain storage layers under VDO
and others on top of VDO:
Under VDO: DM-Multipath, DM-Crypt, and software RAID (LVM or mdraid).
On top of VDO: LVM cache, LVM snapshots, and LVM Thin Provisioning"
For a practical example: in the past I experimented with a storage stack
composed of raid -> vdo -> lvmthin -> xfs serving qemu/kvm virtual disk
files. The lvmthin layer enabled rolling snapshots, and was a key
feature of the test setup.
Now the only method to replicate that is to have two nested LVM
instances, one running vdo and one lvmthin - right?
Regards.
[1]
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/storage_administration_guide/vdo-qs-requirements
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
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next prev parent reply other threads:[~2022-11-16 14:40 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-15 17:42 [linux-lvm] lvm-vdo, snapshots and cache Gionatan Danti
2022-11-15 21:56 ` Zdenek Kabelac
2022-11-15 22:41 ` Gionatan Danti
2022-11-16 10:50 ` Zdenek Kabelac
2022-11-16 14:38 ` Gionatan Danti [this message]
2022-11-16 15:35 ` Zdenek Kabelac
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