Re: [CentOS] Retrieving files from dd backup
On 11/26/2020 07:19 PM, H wrote: > On 11/26/2020 05:27 PM, Leon Fauster via CentOS wrote: >> Am 26.11.20 um 20:10 schrieb H: >>> Running CentOS 7 I have a previously combined backup of a disk with three >>> partitions using dd. I now need to restore one single file from this backup >>> and after perusing the internet, specifically >>> https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, >>> I have done the following: >>> >>> - installed squashfs-tools >>> >>> - installed kpartx >>> >>> - made a squash image of the dd backup and mounted it >>> >>> - used kpartx to create devices for the three partitions under >>> /dev/mapper/loopNpP >>> >>> - I can now mount the first partition, which is the EFI partition, and >>> access it >>> >>> - the second partition, the boot partition, fails to mount since it has the >>> same UUID as the disk I am using in the computer, and of which it is an >>> earlier dd backup. Since I am not interested in the boot partition - at >>> least not right now - I moved on. >>> >>> - I am, however, interested in the third partition which is LUKS encrypted. >>> Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt >>> it with the password >>> >>> - trying to mount the decrypted version with 'mount >>> /dev/mapper/my_encrypted_volume /media/my_device' results in a failure >>> message 'mount: unknown filesystem type 'LVM2_member' >>> >>> - another website, >>> https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, >>> suggests I could run vgdisplay to get the UUID and then rename it using >>> vgrename >>> >>> But, vgdisplay shows only one vg and I am afraid to rename the VG UUID >>> shown by vgdisplay since it might refer to the VG currently in use... >>> >>> Does anyone have any insight or suggestions into the above and how to >>> proceed while being absolutely certain I will not be messing up the running >>> part of the system? >>> >> IIRC: Activate the LVM via: vgchange -a y >> >> and mount the logical volume (LV). >> >> LV can be listed with lvs. The device nodes are under /dev/mapper ... >> >> -- >> Leon >> >> >> >> >> >> ___ >> CentOS mailing list >> CentOS@centos.org >> https://lists.centos.org/mailman/listinfo/centos > OK, I am looking at > https://www.cyberciti.biz/faq/linux-mount-an-lvm-volume-partition-command/. A > couple of follow-up questions: > > - Would activating the LVM with 'vgchange -a y' make any changes, or create > any potential issues, with the system already running? > > - How do I know that the output from 'vgdisplay' refers to this 'new' VG and > not VGs on the running system? > > - To mount the VG, I would have to run: > > -- 'vgscan' > > -- make directory for mounting > > -- 'mount...' to mount the VG > > Is that correct? And it would not create any issues with the running system? > > Thank you in advance. > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos OK, finally had time to delve into this and become a LVM expert (ha!) I got it working and can retrieve files from old dd images, both unencrypted and LUKS encrypted. Note that I did this on another computer than the dd images were made from to avoid UUID conflicts. However, a couple of questions: Section 1: I had no problems mounting and accessing the files for the boot partition but since the home partition is a "LVM2_member", I had to go through some extra steps such as: "vgimportclone --basevgname -i /dev/mapper/mev" (the latter location is an arbitrary name chosen by me) This results in error message: "Error writing device /dev/mapper/mev at 4096 length 512. bcache_invalidate: block (6, 0) still dirty Failed to write mda header to /dev/mapper/mev fd -1" Question 1: - What does this error message really mean? Is this something I ought to fix (although I blithely continued as below...) Section 2: However, after running lvscan, vgchange -ay, ls -lh /dev/mapper to find out which /dev/dm-* to mount (/dev/dm-7) in my case: "mount -o ro,loop /dev/dm-7 mtb3" (the latter again is a mount point arbitrarily chosen by me) Results in another error message about a missing superblock which could be corrected by: "mount -o ro,loop,norecovery /dev/dm-7 mtb3" I was then able to recover the couple of files I needed. Question 2: - Should I do something different when eventually mounting to avoid the error message about a missing superblock? Or is there something wrong with the disk partition I had copied by dd? Looking forward to insight by those more knowledgeable than myself. Many thanks. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Retrieving files from dd backup
On 11/27/2020 02:11 AM, Ralf Prengel wrote: > Simple question > did you try a centos live cd with a all tools to open the system? > Perhaps the easiest way when not trained every day restoring files. > Ralf > > Von meinem iPad gesendet > >> Am 26.11.2020 um 20:11 schrieb H : >> >> Running CentOS 7 I have a previously combined backup of a disk with three >> partitions using dd. I now need to restore one single file from this backup >> and after perusing the internet, specifically >> https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, >> I have done the following: >> >> - installed squashfs-tools >> >> - installed kpartx >> >> - made a squash image of the dd backup and mounted it >> >> - used kpartx to create devices for the three partitions under >> /dev/mapper/loopNpP >> >> - I can now mount the first partition, which is the EFI partition, and >> access it >> >> - the second partition, the boot partition, fails to mount since it has the >> same UUID as the disk I am using in the computer, and of which it is an >> earlier dd backup. Since I am not interested in the boot partition - at >> least not right now - I moved on. >> >> - I am, however, interested in the third partition which is LUKS encrypted. >> Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt it >> with the password >> >> - trying to mount the decrypted version with 'mount >> /dev/mapper/my_encrypted_volume /media/my_device' results in a failure >> message 'mount: unknown filesystem type 'LVM2_member' >> >> - another website, >> https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, >> suggests I could run vgdisplay to get the UUID and then rename it using >> vgrename >> >> But, vgdisplay shows only one vg and I am afraid to rename the VG UUID shown >> by vgdisplay since it might refer to the VG currently in use... >> >> Does anyone have any insight or suggestions into the above and how to >> proceed while being absolutely certain I will not be messing up the running >> part of the system? >> >> Thanks! >> >> ___ >> CentOS mailing list >> CentOS@centos.org >> https://lists.centos.org/mailman/listinfo/centos > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos No, for two reasons. One, I am not trying to restore the entire system, only one file from the dd backup. Second, this is also a training run for the future. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Retrieving files from dd backup
Simple question did you try a centos live cd with a all tools to open the system? Perhaps the easiest way when not trained every day restoring files. Ralf Von meinem iPad gesendet > Am 26.11.2020 um 20:11 schrieb H : > > Running CentOS 7 I have a previously combined backup of a disk with three > partitions using dd. I now need to restore one single file from this backup > and after perusing the internet, specifically > https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, > I have done the following: > > - installed squashfs-tools > > - installed kpartx > > - made a squash image of the dd backup and mounted it > > - used kpartx to create devices for the three partitions under > /dev/mapper/loopNpP > > - I can now mount the first partition, which is the EFI partition, and access > it > > - the second partition, the boot partition, fails to mount since it has the > same UUID as the disk I am using in the computer, and of which it is an > earlier dd backup. Since I am not interested in the boot partition - at least > not right now - I moved on. > > - I am, however, interested in the third partition which is LUKS encrypted. > Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt it > with the password > > - trying to mount the decrypted version with 'mount > /dev/mapper/my_encrypted_volume /media/my_device' results in a failure > message 'mount: unknown filesystem type 'LVM2_member' > > - another website, > https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, > suggests I could run vgdisplay to get the UUID and then rename it using > vgrename > > But, vgdisplay shows only one vg and I am afraid to rename the VG UUID shown > by vgdisplay since it might refer to the VG currently in use... > > Does anyone have any insight or suggestions into the above and how to proceed > while being absolutely certain I will not be messing up the running part of > the system? > > Thanks! > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Retrieving files from dd backup
On 11/26/2020 05:27 PM, Leon Fauster via CentOS wrote: > Am 26.11.20 um 20:10 schrieb H: >> Running CentOS 7 I have a previously combined backup of a disk with three >> partitions using dd. I now need to restore one single file from this backup >> and after perusing the internet, specifically >> https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, >> I have done the following: >> >> - installed squashfs-tools >> >> - installed kpartx >> >> - made a squash image of the dd backup and mounted it >> >> - used kpartx to create devices for the three partitions under >> /dev/mapper/loopNpP >> >> - I can now mount the first partition, which is the EFI partition, and >> access it >> >> - the second partition, the boot partition, fails to mount since it has the >> same UUID as the disk I am using in the computer, and of which it is an >> earlier dd backup. Since I am not interested in the boot partition - at >> least not right now - I moved on. >> >> - I am, however, interested in the third partition which is LUKS encrypted. >> Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt it >> with the password >> >> - trying to mount the decrypted version with 'mount >> /dev/mapper/my_encrypted_volume /media/my_device' results in a failure >> message 'mount: unknown filesystem type 'LVM2_member' >> >> - another website, >> https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, >> suggests I could run vgdisplay to get the UUID and then rename it using >> vgrename >> >> But, vgdisplay shows only one vg and I am afraid to rename the VG UUID shown >> by vgdisplay since it might refer to the VG currently in use... >> >> Does anyone have any insight or suggestions into the above and how to >> proceed while being absolutely certain I will not be messing up the running >> part of the system? >> > > IIRC: Activate the LVM via: vgchange -a y > > and mount the logical volume (LV). > > LV can be listed with lvs. The device nodes are under /dev/mapper ... > > -- > Leon > > > > > > ___ > CentOS mailing list > CentOS@centos.org > https://lists.centos.org/mailman/listinfo/centos OK, I am looking at https://www.cyberciti.biz/faq/linux-mount-an-lvm-volume-partition-command/. A couple of follow-up questions: - Would activating the LVM with 'vgchange -a y' make any changes, or create any potential issues, with the system already running? - How do I know that the output from 'vgdisplay' refers to this 'new' VG and not VGs on the running system? - To mount the VG, I would have to run: -- 'vgscan' -- make directory for mounting -- 'mount...' to mount the VG Is that correct? And it would not create any issues with the running system? Thank you in advance. ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Retrieving files from dd backup
Am 26.11.20 um 20:10 schrieb H: Running CentOS 7 I have a previously combined backup of a disk with three partitions using dd. I now need to restore one single file from this backup and after perusing the internet, specifically https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, I have done the following: - installed squashfs-tools - installed kpartx - made a squash image of the dd backup and mounted it - used kpartx to create devices for the three partitions under /dev/mapper/loopNpP - I can now mount the first partition, which is the EFI partition, and access it - the second partition, the boot partition, fails to mount since it has the same UUID as the disk I am using in the computer, and of which it is an earlier dd backup. Since I am not interested in the boot partition - at least not right now - I moved on. - I am, however, interested in the third partition which is LUKS encrypted. Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt it with the password - trying to mount the decrypted version with 'mount /dev/mapper/my_encrypted_volume /media/my_device' results in a failure message 'mount: unknown filesystem type 'LVM2_member' - another website, https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, suggests I could run vgdisplay to get the UUID and then rename it using vgrename But, vgdisplay shows only one vg and I am afraid to rename the VG UUID shown by vgdisplay since it might refer to the VG currently in use... Does anyone have any insight or suggestions into the above and how to proceed while being absolutely certain I will not be messing up the running part of the system? IIRC: Activate the LVM via: vgchange -a y and mount the logical volume (LV). LV can be listed with lvs. The device nodes are under /dev/mapper ... -- Leon ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
[CentOS] Retrieving files from dd backup
Running CentOS 7 I have a previously combined backup of a disk with three partitions using dd. I now need to restore one single file from this backup and after perusing the internet, specifically https://unix.stackexchange.com/questions/31669/is-it-possible-to-mount-a-gzip-compressed-dd-image-on-the-fly, I have done the following: - installed squashfs-tools - installed kpartx - made a squash image of the dd backup and mounted it - used kpartx to create devices for the three partitions under /dev/mapper/loopNpP - I can now mount the first partition, which is the EFI partition, and access it - the second partition, the boot partition, fails to mount since it has the same UUID as the disk I am using in the computer, and of which it is an earlier dd backup. Since I am not interested in the boot partition - at least not right now - I moved on. - I am, however, interested in the third partition which is LUKS encrypted. Running 'cryptsetup luksOpen /dev/sda3 my_encrypted_volume' I can decrypt it with the password - trying to mount the decrypted version with 'mount /dev/mapper/my_encrypted_volume /media/my_device' results in a failure message 'mount: unknown filesystem type 'LVM2_member' - another website, https://askubuntu.com/questions/766048/mount-unknown-filesystem-type-lvm2-member, suggests I could run vgdisplay to get the UUID and then rename it using vgrename But, vgdisplay shows only one vg and I am afraid to rename the VG UUID shown by vgdisplay since it might refer to the VG currently in use... Does anyone have any insight or suggestions into the above and how to proceed while being absolutely certain I will not be messing up the running part of the system? Thanks! ___ CentOS mailing list CentOS@centos.org https://lists.centos.org/mailman/listinfo/centos
