From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: "Marek Marczykowski-Górecki" <marmarek@invisiblethingslab.com>,
"Zdenek Kabelac" <zdenek.kabelac@gmail.com>
Subject: Re: [linux-lvm] LVM performance vs direct dm-thin
Date: Sun, 30 Jan 2022 17:14:43 -0500 [thread overview]
Message-ID: <YfcN6KHxLe3/krTX@itl-email> (raw)
In-Reply-To: <30ba3f0683afb9c3b60d96ac0019ced4ce9bb5b8.camel@gathman.org>
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On Sun, Jan 30, 2022 at 04:39:30PM -0500, Stuart D. Gathman wrote:
> On Sun, 2022-01-30 at 11:45 -0500, Demi Marie Obenour wrote:
> > On Sun, Jan 30, 2022 at 11:52:52AM +0100, Zdenek Kabelac wrote:
> > >
> >
> > > Since you mentioned ZFS - you might want focus on using 'ZFS-only'
> > > solution.
> > > Combining ZFS or Btrfs with lvm2 is always going to be a painful
> > > way as
> > > those filesystems have their own volume management.
> >
> > Absolutely! That said, I do wonder what your thoughts on using loop
> > devices for VM storage are. I know they are slower than thin
> > volumes,
> > but they are also much easier to manage, since they are just ordinary
> > disk files. Any filesystem with reflink can provide the needed
> > copy-on-write support.
>
> I use loop devices for test cases - especially with simulated IO
> errors. Devs really appreciate having an easy reproducer for
> database/filesystem bugs (which often involve handling of IO errors).
> But not for production VMs.
>
> I use LVM as flexible partitions (i.e. only classic LVs, no thin pool).
> Classic LVs perform like partitions, literally using the same driver
> (device mapper) with a small number of extents, and are if anything
> more recoverable than partition tables. We used to put LVM on bare
> drives (like AIX did) - who needs a partition table? But on Wintel,
> you need a partition table for EFI and so that alien operating systems
> know there is something already on a disk.
>
> Your VM usage is different from ours - you seem to need to clone and
> activate a VM quickly (like a vps provider might need to do). We
> generally have to buy more RAM to add a new VM :-), so performance of
> creating a new LV is the least of our worries.
To put it mildly, yes :). Ideally we could get VM boot time down to
100ms or lower.
--
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab
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next prev parent reply other threads:[~2022-01-30 22:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-29 20:34 [linux-lvm] LVM performance vs direct dm-thin Demi Marie Obenour
2022-01-29 21:32 ` Zdenek Kabelac
2022-01-30 0:32 ` Demi Marie Obenour
2022-01-30 10:52 ` Zdenek Kabelac
2022-01-30 16:45 ` Demi Marie Obenour
2022-01-30 17:43 ` Zdenek Kabelac
2022-01-30 20:27 ` Gionatan Danti
2022-01-30 21:17 ` Demi Marie Obenour
2022-01-31 7:52 ` Gionatan Danti
2022-02-02 2:09 ` Demi Marie Obenour
2022-02-02 10:04 ` Zdenek Kabelac
2022-02-03 0:23 ` Demi Marie Obenour
2022-02-03 12:04 ` Zdenek Kabelac
2022-02-03 12:04 ` Zdenek Kabelac
2022-01-30 21:39 ` Stuart D. Gathman
2022-01-30 22:14 ` Demi Marie Obenour [this message]
2022-01-31 21:29 ` Marian Csontos
2022-02-03 4:48 ` Demi Marie Obenour
2022-02-03 12:28 ` Zdenek Kabelac
2022-02-04 0:01 ` Demi Marie Obenour
2022-02-04 10:16 ` Zdenek Kabelac
2022-01-31 7:47 ` Gionatan Danti
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