Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
Hi Alasdair, Thank for comments. That means we should update the comments to the latest, this can help to tell the user "this is advanced option". Thanks Gang > -Original Message- > From: linux-lvm-boun...@redhat.com > [mailto:linux-lvm-boun...@redhat.com] On Behalf Of Alasdair G Kergon > Sent: 2019年10月14日 21:20 > To: LVM general discussion and development > Subject: Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf > can be edited? > > On Mon, Oct 14, 2019 at 10:52:02AM +, Gang He wrote: > > That means we should tell the user, you should not edit this option (dir = > "/dev") in the lvm.conf, right? > > The existing comment is incomplete and should be updated to mention the > other effects. The option pre-dates udev and so the "newer" > interlocking there ought to be mentioned. The description of 'advanced' > could also be updated to explain that that means you should not change it > unless you know exactly what you are doing! The option exists to simplify > some development, test and support scenarios where you want to have two or > more distinct userspace LVM instances running on a single machine. For > example, to try to reproduce a certain type of user-reported bug you might set > up a temporary /dev in a non-default location with contents that match that > user's system and point the tools at that using this option. > > Alasdair > > ___ > linux-lvm mailing list > linux-lvm@redhat.com > https://www.redhat.com/mailman/listinfo/linux-lvm > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
On Mon, Oct 14, 2019 at 10:52:02AM +, Gang He wrote: > That means we should tell the user, you should not edit this option (dir = > "/dev") in the lvm.conf, right? The existing comment is incomplete and should be updated to mention the other effects. The option pre-dates udev and so the "newer" interlocking there ought to be mentioned. The description of 'advanced' could also be updated to explain that that means you should not change it unless you know exactly what you are doing! The option exists to simplify some development, test and support scenarios where you want to have two or more distinct userspace LVM instances running on a single machine. For example, to try to reproduce a certain type of user-reported bug you might set up a temporary /dev in a non-default location with contents that match that user's system and point the tools at that using this option. Alasdair ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
Dne 14. 10. 19 v 12:52 Gang He napsal(a): Hi Zdenek, Thanks for explaining. That means we should tell the user, you should not edit this option (dir = "/dev") in the lvm.conf, right? Basically yes. The option is there for 'skilled' users who know exactly how the whole 'device creation process' works - essentially these days this option is mostly useful only for some testing... Regards Zdenek ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
Hi Zdenek, Thanks for explaining. That means we should tell the user, you should not edit this option (dir = "/dev") in the lvm.conf, right? Thanks Gang > -Original Message- > From: Zdenek Kabelac [mailto:zkabe...@redhat.com] > Sent: 2019年10月14日 18:40 > To: LVM general discussion and development ; Gang > He > Subject: Re: devices/dir configuration option in /etc/lvm/lvm.conf can be > edited? > > Dne 14. 10. 19 v 10:00 Gang He napsal(a): > > Hello List, > > > > By default, devices/dir configuration option in /etc/lvm/lvm.conf is > > "=/dev". > > But, if I edit this configuration option, e.g. dir = "/dev/lvm", then > > lvcreate > command will fail. > > > > sles12sp4-node:/dev # lvcreate -L2G -ay -n testlv vgdata > >/dev/lvm/vgdata/testlv: not found: device not cleared > >Aborting. Failed to wipe start of new LV. > > > > I am using lvm 2.02.183(or 180), this option can be edit individually? > > or any other option will affect this option, then lead to lvcreate failure. > > Hi > > The option is not so easy to explain: > > In the first place on a today's system you shall never ever need to change > this > setting - as majority of systems runs 'udev' or something similar in a fixed > position /dev. > > So symlinks & devices appears at this directory (and without 'lvm2' direct > work) only as a consequence of configured udev rules. > > So now surely comes the obvious question - why the 'setting' even exists > when you should always use '/dev' anyway right ;) ? > > And here the answer is longer - lvm2 is very 'oldish' project from 'dark' era > before udev took control over devices - and in this old era you could have > configured different device directory for devices created by lvm2 - since it's > been lvm2 physically creating these devices. > > The usability for normal users is relatively questionable since almost every > user wants his devices in /dev dir anyway, but couple wanted to maintain > separate dir for lvm2 devices. > > The 'other' use-case is for testing - where i.e. lvm2 test suite is/(or was) > able to > run its tests in completely isolated device directory. > > But to be able to use this 'capability' - one has to enable other lvm.conf > setting: 'activation/verify_udev_operations=1' - when enabled lvm2 will > ensure devices are in give directory. > > But (and it's BIG BUT) this shall never be enabled on a system with > running > udevd and /dev dir set - as basically nothing else then udevd is supposed to > be creating anything in /dev dir. > > So hopefully this explains most of the question you may have about this > setting. > > Regards > > Zdenek > > ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
Re: [linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
Dne 14. 10. 19 v 10:00 Gang He napsal(a): Hello List, By default, devices/dir configuration option in /etc/lvm/lvm.conf is "=/dev". But, if I edit this configuration option, e.g. dir = "/dev/lvm", then lvcreate command will fail. sles12sp4-node:/dev # lvcreate -L2G -ay -n testlv vgdata /dev/lvm/vgdata/testlv: not found: device not cleared Aborting. Failed to wipe start of new LV. I am using lvm 2.02.183(or 180), this option can be edit individually? or any other option will affect this option, then lead to lvcreate failure. Hi The option is not so easy to explain: In the first place on a today's system you shall never ever need to change this setting - as majority of systems runs 'udev' or something similar in a fixed position /dev. So symlinks & devices appears at this directory (and without 'lvm2' direct work) only as a consequence of configured udev rules. So now surely comes the obvious question - why the 'setting' even exists when you should always use '/dev' anyway right ;) ? And here the answer is longer - lvm2 is very 'oldish' project from 'dark' era before udev took control over devices - and in this old era you could have configured different device directory for devices created by lvm2 - since it's been lvm2 physically creating these devices. The usability for normal users is relatively questionable since almost every user wants his devices in /dev dir anyway, but couple wanted to maintain separate dir for lvm2 devices. The 'other' use-case is for testing - where i.e. lvm2 test suite is/(or was) able to run its tests in completely isolated device directory. But to be able to use this 'capability' - one has to enable other lvm.conf setting: 'activation/verify_udev_operations=1' - when enabled lvm2 will ensure devices are in give directory. But (and it's BIG BUT) this shall never be enabled on a system with running udevd and /dev dir set - as basically nothing else then udevd is supposed to be creating anything in /dev dir. So hopefully this explains most of the question you may have about this setting. Regards Zdenek ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
[linux-lvm] devices/dir configuration option in /etc/lvm/lvm.conf can be edited?
Hello List, By default, devices/dir configuration option in /etc/lvm/lvm.conf is "=/dev". But, if I edit this configuration option, e.g. dir = "/dev/lvm", then lvcreate command will fail. sles12sp4-node:/dev # lvcreate -L2G -ay -n testlv vgdata /dev/lvm/vgdata/testlv: not found: device not cleared Aborting. Failed to wipe start of new LV. I am using lvm 2.02.183(or 180), this option can be edit individually? or any other option will affect this option, then lead to lvcreate failure. Thanks Gang ___ linux-lvm mailing list linux-lvm@redhat.com https://www.redhat.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
