From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <511CE47E.1040104@redhat.com> Date: Thu, 14 Feb 2013 14:19:58 +0100 From: Marian Csontos MIME-Version: 1.0 References: <511CE455.8080404@redhat.com> In-Reply-To: <511CE455.8080404@redhat.com> Content-Transfer-Encoding: 7bit Subject: [linux-lvm] Fwd: Re: [lvm-devel] create physical partition from logical partition Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: LVM general discussion and development , fakhreddine HABIB This list! I am sorry. On 02/14/2013 02:18 PM, Marian Csontos wrote: > Hello, I did answer here and it still applies. > > Though I am sure I have not got you an ill advice, please, *use reply to > list* or reply to all, so other can review, fix typos/mistakes in steps, > or provide an additional information. > > > [root@zaphod ~]# lvcreate -L 1G -n lv vg_zaphod > > Logical volume "lv" created > > [root@zaphod ~]# lvresize -L 2G vg_zaphod/lv > > Extending logical volume lv to 2.00 GiB > > Logical volume lv successfully resized > > [root@zaphod ~]# lvresize -L 1G vg_zaphod/lv > > WARNING: Reducing active logical volume to 1.00 GiB > > THIS MAY DESTROY YOUR DATA (filesystem etc.) > > Do you really want to reduce lv? [y/n]: n > > Briefly, answered "y" here lvresize does what asked for and cuts > filesystem into two. Though it says it will destroy data it was still > reversible operation, resizing incomplete FS later not so, but running > fsck dealt an ultimate blow to the FS. > > > Now, the important question: Have you done a backup before? > > I hope not getting an answer does not mean no. > > -- Marian > > > On 02/10/2013 09:54 PM, Marian Csontos wrote: >> On 02/10/2013 12:23 AM, fakhreddine HABIB wrote: >>> Thank you again Marian. >>> >>> I tried first with the second point to run `fdisk /dev/sda` and i change >>> the `Id` of /dev/sda2 to `8e`, using the Live Cd of Ubuntu. >>> Now i can see the VG group ' vg_regalcauchy, thank you a lot for this >>> point. >>> >>> Now, i have a problem .. i don't know what the reason. I tried after to >>> reduce my volume in ' dev/vg_regalcaucy/lv_home' to have a big space to >>> install Ubuntu, when i reduce the volume, i had a problem with the >>> filesystem size was 26214400 blocks and the physical size of the >>> device is >>> 24962048. >>> When i use the resize2fs it didn't work, i fix the file system size >>> manually to 24962048. >> >> Hello. Oh no! I am afraid this is the most common mistake I have seen: >> people do first shrink the LV and then the FS, while it must be done in >> reverse order. The wrong way just removes part of FS first, so there may >> be uncomplete files. And any attempt to fix the FS makes it worse - >> links to data in the removed part of FS are broken now. >> >> NOTE: There is a `fsadm` command which does handle resizing of both LVs >> and FSs which should be used instead. >> >> Now, the important question: Have you done a backup before? >> >> *Yes*: Very well! Just restore the data from Backup and repeat just >> shrink the FS first and everything should be fine. >> >> *No*: I am afraid there are going to be files lost, depends very much >> how full the filesystem was. >> >> If possible do a backup now - you may need to return to it and retry... >> >> Then you should increase the size of the LV back and then increase the >> FS size back to original value. >> >> Try running fsck now, but be prepared for lot of errors. >> >> You should check files in lost+found and if any valuable data are there: >> fragments of your files,... >> >> -- Marian >> >>> but when i want to mount the ' dev/vg_regalcaucy/lv_home', i have the >>> message : >>> >>> mount: wrong fs type, bad option, bad superblock on >>> /dev/vg_regalcaucy/lv_home, >>> missing codepage or helper program, or other error >>> In some cases useful info is found in syslog - try >>> dmesg | tail or so >>> >>> >>> And when i try to reboot my Centos system i have the message in the >>> snapshot >>> >>> http://cjoint.com/data/0Bkatrr9BNg.htm >>> >>> Can you help me please to find a solution, i use the partition magic >>> Live >>> CD to use the shell, because i can't have an access to the system... >>> and i >>> don't know how can'i install in the system the ' nfs-common ' if it >>> need. >>> >>> Thank you. >>> >>> F. H >>> >>> >>> >>> >>> >>> >>> >>> >>> 2013/2/8 Marian Csontos >>> >>>> On 02/08/2013 04:38 AM, fakhreddine HABIB wrote: >>>> >>>>> First thank you Marian. >>>>> >>>> >>>> Hello, >>>> >>>> >>>> >>>>> About the method to reuduce the Pv, i think is risked... I don't >>>>> want to >>>>> take any risk of loosing data ... >>>>> >>>> >>>> - pvresize will not resize if there are data in the trailing disk >>>> space to >>>> about to be shrinked >>>> >>>> - pvmove will mirror the data until moved successfully and even on >>>> failure >>>> will start again >>>> >>>> There is a short interval when LVM metadata are updated where system >>>> crash >>>> could result in troubles, but this is no more risk than increasing >>>> logical >>>> volume size... >>>> >>>> If you need creating new partition, you have no other option than >>>> resizing >>>> the PV. >>>> >>>> *Backups, backups, backups!* >>>> >>>> Though I am quite confident LVM user now, I am always doing backups >>>> when >>>> shuffling round partitions. >>>> >>>> Perhaps the easiest way if you have a spare USB HDD around is to run a >>>> live CD and `dd` the /dev/sda there (like this `dd if=/dev/sda >>>> of=/path/to/file/on/your/usb/**disk.img bs=1M`) If anything goes wrong, >>>> you can simply switch the if and of params, and everything will be back >>>> where it was before. >>>> >>>> *Virtualization?* >>>> >>>> Actually, there is an option: if your machine is HVM (Virtualization >>>> enabled) you could still install and run Ubuntu in a virtual machine. >>>> >>>> CONS: slower, more memory consuming (2 OS are running at the same >>>> time), >>>> not all HW is accessible... >>>> >>>> >>>> >>>>> I tried your idea if i can install ubuntu and Centos in the same >>>>> Physical >>>>> partition, using a logical one .. but i can,t find the way to do >>>>> that.. >>>>> Ubuntu installation interface give the whole /dev/sda2 but i can't see >>>>> the logical volumes (I talk about logical volumes of a LV group) >>>>> (attached >>>>> pics) >>>>> >>>> >>>> Too bad. Looks like the installer does not recognize LVM partition. >>>> >>>> Is it possible the partition used does not have a partition header? >>>> >>>> Run `fdisk /dev/sda` and there you could try `p` to print partitions. >>>> `Id` >>>> should be `8e` and `System` Linux LVM. If that's not so, try `t` and >>>> change >>>> 2-nd partition's type to `8e`. >>>> >>>> That may help ubuntu recognize the LVM partition. >>>> >>>> If not, try asking on Ubuntu forum... >>>> >>>> -- Marian >>>> >>>> >>>>> thank you. >>>>> >>>>> >>> >> > > -- > lvm-devel mailing list > lvm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/lvm-devel