From: Lukas Czerner <lczerner@redhat.com>
To: Theodore Ts'o <tytso@mit.edu>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>,
darrick.wong@oracle.com
Subject: Re: [PATCH 8/9] e2scrub_all: refactor device probe loop
Date: Thu, 21 Mar 2019 20:49:01 +0100 [thread overview]
Message-ID: <20190321194901.44eeu6l7mxsd7k4j@work> (raw)
In-Reply-To: <20190321174811.GF9434@mit.edu>
On Thu, Mar 21, 2019 at 01:48:11PM -0400, Theodore Ts'o wrote:
> On Thu, Mar 21, 2019 at 11:27:42AM +0100, Lukas Czerner wrote:
> >
> > Snapshot of a thinspanshot is allowed though, so we might want to
> > include those. Not sure if it's wise to do it by default, but regardless
> > it's probably something for a separate change.
>
> Yeah, it's definitely a separate change. One potential design
> question is that for a thin volume, you can do both a thin or a think
> snapshot, and in some cases one might succeed while the other will
> fail. So do we make this choice be a parameter that we set in the
> config file, or do we try to see if there is sufficient spare
> freespace for a thick snapshot (and then do that), or a thin snapshot
> (and then do that) --- and which should use prefer?
That's a good question. I am not sure it makes sense to allow choice
between thin/thick snapshots of thin volume. Just pick one, ideally it
would be thin snapshot of thin volume.
>
> The other thing I'll note is that in order for us to tell whether
> something is a thin or thick LV, we're going to to need to ask lvs to
> return multiple parameters, so the optimization of using:
>
> for NAME in $(lvs -o lv_path --noheadings -S...) ; do
> ...
> done
>
> will no longer work. (Or we end up calling lvs a second time, which
> is less efficient.)
Yeah, however calling lvs twice might still be better then calling
lsblk for every lv ? This can be easily benchmarked.
first it would be for a non-thin volumes so
-S lv_active=active,lv_role=public,lv_role!=snapshot,segtype!=thin
and second for thin volumes and thin snapshots
-S lv_active=active,lv_role=public,segtype=thin
Note that by default thin snapshots are not active so they will not be
checked unless user activated them.
>
> Just curious --- do we know how commonly thin LV's are being used by
> customers of various distros? I assume enterprise distro users will
> be the most conservative, but how common is the uptake of thin LV's by
> Fedora and OpenSuSE users?
I wish I knew. I think that for workstation users it's the defaults that
matters the most so I would not expect thin LV's to be used much there.
Qubes OS being most notable exception I think.
I'd think that thin would be mostly used for virtualization and storage
appliances. I'll ask around, Fedora should have some stats.
-Lukas
>
> - Ted
next prev parent reply other threads:[~2019-03-21 19:49 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 2:02 [PATCH 1/9] e2scrub: check to make sure lvm2 is installed Theodore Ts'o
2019-03-21 2:02 ` [PATCH 2/9] debian: drop lvm2 from the recommends line Theodore Ts'o
2019-03-21 3:57 ` Darrick J. Wong
2019-03-21 2:02 ` [PATCH 3/9] Fix "make install-strip" Theodore Ts'o
2019-03-21 2:02 ` [PATCH 4/9] e2scrub: fix up "make install-strip" support Theodore Ts'o
2019-03-21 2:02 ` [PATCH 5/9] e2fscrub: add the -n option which shows what commands e2scrub would execute Theodore Ts'o
2019-03-21 3:59 ` Darrick J. Wong
2019-03-21 10:57 ` Lukas Czerner
2019-03-21 14:32 ` Theodore Ts'o
2019-03-21 2:02 ` [PATCH 6/9] e2scrub_all: add the -n option which shows what e2scrub_all would do Theodore Ts'o
2019-03-21 4:01 ` Darrick J. Wong
2019-03-21 2:02 ` [PATCH 7/9] e2scrub_all: make sure there's enough free space for a snapshot Theodore Ts'o
2019-03-21 4:02 ` Darrick J. Wong
2019-03-21 11:18 ` Lukas Czerner
2019-03-21 14:26 ` Theodore Ts'o
2019-03-21 2:02 ` [PATCH 8/9] e2scrub_all: refactor device probe loop Theodore Ts'o
2019-03-21 4:05 ` Darrick J. Wong
2019-03-21 10:27 ` Lukas Czerner
2019-03-21 14:31 ` Theodore Ts'o
2019-03-21 15:57 ` Lukas Czerner
2019-03-21 18:24 ` Theodore Ts'o
2019-03-21 20:17 ` Lukas Czerner
2019-03-21 20:48 ` Theodore Ts'o
2019-03-21 21:14 ` Lukas Czerner
2019-03-21 22:04 ` Theodore Ts'o
2019-03-21 22:08 ` Theodore Ts'o
2019-03-22 9:38 ` Lukas Czerner
2019-03-21 20:09 ` Andreas Dilger
2019-03-21 17:48 ` Theodore Ts'o
2019-03-21 19:49 ` Lukas Czerner [this message]
2019-03-21 20:23 ` Theodore Ts'o
2019-03-21 16:10 ` Lukas Czerner
2019-03-21 2:02 ` [PATCH 9/9] e2scrub,e2scrub_all: print a (more understandable) error if not run as root Theodore Ts'o
2019-03-21 4:04 ` Darrick J. Wong
2019-03-21 11:36 ` Lukas Czerner
2019-03-21 14:40 ` Theodore Ts'o
2019-03-21 3:55 ` [PATCH 1/9] e2scrub: check to make sure lvm2 is installed Darrick J. Wong
-- strict thread matches above, loose matches on Subject: below --
2019-03-21 20:25 [PATCH -v2 0/9] e2fsprogs: e2scrub cleanups Theodore Ts'o
2019-03-21 20:25 ` [PATCH 8/9] e2scrub_all: refactor device probe loop Theodore Ts'o
2019-03-21 20:55 ` Lukas Czerner
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