From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zdenek Kabelac Date: Thu, 3 Mar 2016 11:32:12 +0100 Subject: directory instead of link for thinpools? In-Reply-To: <56D80F3A.4010700@mglug.de> References: <56D80F3A.4010700@mglug.de> Message-ID: <56D812AC.9020600@redhat.com> List-Id: To: lvm-devel@redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Dne 3.3.2016 v 11:17 Oliver Rath napsal(a): > Hi list, > > Im using thinpool-devices for a longer time (3+ years) and thinking > about a more intuitive representation in /dev/. > > If Im right, Thinpools are not used directly (as device), only as pool > for thinpool-based devices (these with --virtualsize instead of --size). > > I.e. we are using "vg" as volumegroup and "pool" as thinpool, > "pooldevice" a "pool" based virtual device and "standarddevice" a normal > (non-thinpool) lvm-device, then following happens: > > - /dev/vg/pool is a link to /dev/dm-X, which is a device node, but never > used directly > - /dev/vg/pooldevice is also a link to /dev/dm-Y, but now it is useable > directly > - /dev/vg/standarddevice is also a link to /dev/dm-Z, useable directly, > but not snappable like thinpool devices > > This is imho a bit confusing. > > My idea now would be to change the representation of "pool" from a link > to this (never directly used) device to a directory, which includes the > links to the pooldevices. Now the representation would look like this > ("/" is dir, "@" is link): > > /dev/vg/standarddevice@ > /dev/vg/pool/ > /dev/vg/pool/pooldevice@ > > > Now I tried to create this with udev-rules, but unfortunatly I didnt > find any possibility to differ between standarddevices, pools and > pool-based devices. Is there any possibility to recogize this for > udev-rules? > > What do you think generally about this idea? > Hi NACK It's already complex with existing udev & system rules - so adding new complicated stuff makes no sense. If you need to get some 'visually' similar layout - just prepend pool name prefix into your LV name. But there is not going to be subdir support for LVs in lvm2. It stays with simple rule: user usable LV has device path: /dev/vgname/lvname and thinLV is user usable LV and we are not going change this key rule. Regards Zdenek