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From: "Theodore Ts'o" <tytso@mit.edu>
To: Lukas Czerner <lczerner@redhat.com>
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 13:48:11 -0400	[thread overview]
Message-ID: <20190321174811.GF9434@mit.edu> (raw)
In-Reply-To: <20190321102742.k2oos4epoj6fyjao@work>

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?

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.)

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?

						- Ted

  parent reply	other threads:[~2019-03-21 17:48 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 [this message]
2019-03-21 19:49       ` Lukas Czerner
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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