Bug#783089: debian-installer: Cannot rescue a system installed on a raid1 lvm
Le 2015-04-22 14:20, Lennart Sorensen a écrit : On Wed, Apr 22, 2015 at 07:49:02AM +0200, Jean-Yves LENHOF wrote: Because I prefer do it this way... lvm raid is more the traditionnal unix way of doing it (AIX and HP-UX for sure) Taste is personnal... There are advantages and inconvenients in all of them (Linux/AIX/HP-UX/True64/Solaris/FreeBSD/whatever) FOR AIX vs linux some examples : some pro : smitty is nicely implemented (there was linuxconf in the past days of linux but not maintained anymore) mksysb is something nice to use to restore a system or to install a system with the same configuration... alternate install is something interesting when upgrading from an OS version to another one (using an alternate lvm mirror) some con : odm is something you should not touch without IBM advise, etc.. dependencies in packages are too hard and upgrading a package tend to have everything upgrading... But we are not here to speak about proprietary... but about Linux, so I will not elaborate more on that. That doesn't mean it is a good idea. Those two certainly qualify as the most unpleasant unix systems I have ever had to work with. Why it is very inflexible ? It found it quite flexible. You can't easily add disks to the volume group in raid mode (as far as I recall the documentation last I looked at it). There are certainly restrictions on how to you expand volumes when lvm raid is in use. I just add a disk on my test partition... Done a pvcreate on it, done a vgextend on it without problem. Done a lvextend on a logical partition... Resize my slashlv file system. No problem at all. Did you remake some recent tests ? What is the limitation you are speaking about ? The one I know is that you can't use lvm raid1 in a cluster yet. (It's written in the RedHat Enterprise 7 Logical Volume Documentation) Perhaps the md raid support is there from a longer time because raid1 support (which is different from mirror support) in the kernel (and in lvm2 tools) came later... But things changes and I saw a lot of good things coming in LVM like thin lvm support or cache lvm support. Read redhat docs, such things are supported by RedHat since RedHat Enterprise 6.4 or such. Well certainly grub understands md raid, and it understands some lvm. It might not understand lvm with raid. Following the grub development mailing list for a number of years now, I can say I have never seen anyone ask about it or even mention it. I think it is also the first time I have seen it mentioned on any of the debian lists I follow. You should have read my bug report about grub... There is at least one another person than me that create the bug report ;-) https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=782591 http://savannah.gnu.org/bugs/?func=detailitemitem_id=44534 http://lists.gnu.org/archive/html/bug-grub/2015-04/msg3.html and you should probably read more carefully the list : http://lists.gnu.org/archive/html/grub-devel/2014-08/msg00024.html Certainly using lvm on top of md raid has worked for years for me and the debian rescue knows how to deal with is, as does knoppix and lots of other rescue systems. The lvm raid, no idea. When I looked at it a few years ago it cretainly sounded like a bad option so I avoided it. Some years ago you probably test the mirror type... which I agree is not a so good solution. I speak about the raid1 type which is different raid1 is there since 2013 (there's no clear appareance of the first commit related) : https://git.fedorahosted.org/cgit/lvm2.git/tree/WHATS_NEW For mirror, the mirroring is rebuilt at each reboot For raid1, the mirroring isn't rebuilt at each reboot I will see if I can provide a patch... because I think that discussion is rubbish and code is better. I think it's just an option to add somewhere to enable the built of this kernel module in an udeb. For the debian-installer part (for this bug report here I speak about rescuing) I will make another wishlist bug report (there will be more impact because there will be some more device with rmeta in their name) Please take the time to enable this module kernel in the udeb. Regards, -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#783089: debian-installer: Cannot rescue a system installed on a raid1 lvm
On Wed, Apr 22, 2015 at 07:49:02AM +0200, Jean-Yves LENHOF wrote: Because I prefer do it this way... lvm raid is more the traditionnal unix way of doing it (AIX and HP-UX for sure) That doesn't mean it is a good idea. Those two certainly qualify as the most unpleasant unix systems I have ever had to work with. Why it is very inflexible ? It found it quite flexible. You can't easily add disks to the volume group in raid mode (as far as I recall the documentation last I looked at it). There are certainly restrictions on how to you expand volumes when lvm raid is in use. Perhaps the md raid support is there from a longer time because raid1 support (which is different from mirror support) in the kernel (and in lvm2 tools) came later... But things changes and I saw a lot of good things coming in LVM like thin lvm support or cache lvm support. Read redhat docs, such things are supported by RedHat since RedHat Enterprise 6.4 or such. Well certainly grub understands md raid, and it understands some lvm. It might not understand lvm with raid. Following the grub development mailing list for a number of years now, I can say I have never seen anyone ask about it or even mention it. I think it is also the first time I have seen it mentioned on any of the debian lists I follow. Certainly using lvm on top of md raid has worked for years for me and the debian rescue knows how to deal with is, as does knoppix and lots of other rescue systems. The lvm raid, no idea. When I looked at it a few years ago it cretainly sounded like a bad option so I avoided it. -- Len Sorensen -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#783089: debian-installer: Cannot rescue a system installed on a raid1 lvm
Package: debian-installer Severity: normal Tags: d-i Dear Maintainer, I created a virtual server with 2 disks of the same size. (Problem wil be the same on a physical server with 2 disks of the same size) I did a minimum installation with : - a partition on the whole disk on each disk of type LVM. (/dev/vda1, /dev/vda2) - a volume group with name rootvg with /dev/vda1 - Everything on lvm, with /dev/rootvg/slashlv mounted on / and /dev/rootvg/swaplv for swap (a minimum partitioned system, I create more logical volume on my servers) - grub on /dev/vda And did a reboot after the installation... I can work on the server without problem... After a successul login under root, I did : - vgextend /dev/rootvg /dev/vdb1 - lvconvert --type raid1 -m 1 /dev/rootvg/slashlv - lvconvert --type raid1 -m 1 /dev/rootvg/swaplv - wait for the raid to be completely rebuilded (I checked with the lvs command) I can work on the server without problem... But If I reboot, grub can't regnosize my installation... The message (recopied manually) is : Booting from Hard Disk... error: disk `lvmid/Gwx3dG-v00h-9hJU-FVuk-Il8Z-bFUK-i6DkfU/KpVdER-OEMM-MWik-vKwM-hWxp-MeJf-LMnsf7' not found. Entering rescue mode... grub rescue So I try to reboot with the rescue mode but the CD of debian lack the module dm-raid on the kernel part. (Probably on a udeb package but don't know yet exactly which one, so I created this bug report against debian-installer), so I cannot access my disk anymore !!! Imagine you do this on a production server and you did'nt reboot before a long time. For the record, I already filled a bug report for the grub problem on http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=782591 -- System Information: Debian Release: 8.0 APT prefers testing APT policy: (500, 'testing') Architecture: amd64 (x86_64) Kernel: Linux 3.16.0-4-amd64 (SMP w/1 CPU core) Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#783089: debian-installer: Cannot rescue a system installed on a raid1 lvm
On Wed, Apr 22, 2015 at 12:28:26AM +0200, Jean-Yves LENHOF wrote: Package: debian-installer Severity: normal Tags: d-i Dear Maintainer, I created a virtual server with 2 disks of the same size. (Problem wil be the same on a physical server with 2 disks of the same size) I did a minimum installation with : - a partition on the whole disk on each disk of type LVM. (/dev/vda1, /dev/vda2) - a volume group with name rootvg with /dev/vda1 - Everything on lvm, with /dev/rootvg/slashlv mounted on / and /dev/rootvg/swaplv for swap (a minimum partitioned system, I create more logical volume on my servers) - grub on /dev/vda And did a reboot after the installation... I can work on the server without problem... After a successul login under root, I did : - vgextend /dev/rootvg /dev/vdb1 - lvconvert --type raid1 -m 1 /dev/rootvg/slashlv - lvconvert --type raid1 -m 1 /dev/rootvg/swaplv - wait for the raid to be completely rebuilded (I checked with the lvs command) Whyever would you use lvm raid rather than md raid with lvm on top? As far as I understand it, lvm raid is very inflexible and makes it hard to ever make changes to the lvm in the future, while if you use md raid you are using something that is very flexible as raid and can easily be extended, and lvm on top of that is very flexible too. Basically your chosen setup is very unusual, and as far as I understand it highly discouraged. It will also be very hard to find anyone to help you if there are problems because it is so unusual (the normal setup works better and makes more sense, so that is what almost everyone uses). -- Len Sorensen -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
Bug#783089: debian-installer: Cannot rescue a system installed on a raid1 lvm
Hi, Le 22/04/2015 03:47, Lennart Sorensen a écrit : On Wed, Apr 22, 2015 at 12:28:26AM +0200, Jean-Yves LENHOF wrote: Package: debian-installer Severity: normal Tags: d-i Dear Maintainer, I created a virtual server with 2 disks of the same size. (Problem wil be the same on a physical server with 2 disks of the same size) I did a minimum installation with : - a partition on the whole disk on each disk of type LVM. (/dev/vda1, /dev/vda2) - a volume group with name rootvg with /dev/vda1 - Everything on lvm, with /dev/rootvg/slashlv mounted on / and /dev/rootvg/swaplv for swap (a minimum partitioned system, I create more logical volume on my servers) - grub on /dev/vda And did a reboot after the installation... I can work on the server without problem... After a successul login under root, I did : - vgextend /dev/rootvg /dev/vdb1 - lvconvert --type raid1 -m 1 /dev/rootvg/slashlv - lvconvert --type raid1 -m 1 /dev/rootvg/swaplv - wait for the raid to be completely rebuilded (I checked with the lvs command) Whyever would you use lvm raid rather than md raid with lvm on top? Because I prefer do it this way... lvm raid is more the traditionnal unix way of doing it (AIX and HP-UX for sure) As far as I understand it, lvm raid is very inflexible and makes it hard to ever make changes to the lvm in the future, while if you use md raid you are using something that is very flexible as raid and can easily be extended, and lvm on top of that is very flexible too. Why it is very inflexible ? It found it quite flexible. Basically your chosen setup is very unusual, and as far as I understand it highly discouraged. It will also be very hard to find anyone to help you if there are problems because it is so unusual (the normal setup works better and makes more sense, so that is what almost everyone uses). Perhaps the md raid support is there from a longer time because raid1 support (which is different from mirror support) in the kernel (and in lvm2 tools) came later... But things changes and I saw a lot of good things coming in LVM like thin lvm support or cache lvm support. Read redhat docs, such things are supported by RedHat since RedHat Enterprise 6.4 or such. Regards, -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of unsubscribe. Trouble? Contact listmas...@lists.debian.org
