- luv-main - luv.asn.au

BTRFS and ZFS training
by Russell Coker 27 Jan '20

27 Jan '20

https://doc.coker.com.au/training/btrfs-training-exercises/ https://doc.coker.com.au/training/zfs-training-exercises/ I've put some simple BTRFS and ZFS training exercises at the above URLs (this is the training that was done at a LUV Saturday meeting in 2015). As they involve deliberately corrupting data to exercise the filesystems it's a good idea to to this on a VM so a typo won't cause problems. I can give access to a VM for doing this if anyone needs it. But the system in question doesn't have a lot of RAM so anyone who gets a VM will need to complete the training reasonably quickly. If you have any suggestions for additions to the training please be specific about what commands to run. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

2 1

Re: Rebuild after disk fail
by Andrew Greig 17 Jan '20

17 Jan '20

Hi All, I found this document from Feb 2019, and after some amazing help from Craig and others I came up with this: Proposed road map for an installation of a system disk and two Data disks set up as a RAID1 array 1Tb SSD and 2 x 2Tb SATA HDDs Using Gparted partition the SSD 512MB EFI Partition dev/sda1 formatted FAT32 primary (boot?) 8 Gb SWAP rest of the disk _*/*__dev/_sda3primary formatted btrfs Partition the first HDD /dev/sdb1primary formatted btrfs (Disk has data now so leave this alone) Second HDD same size leave completely blank (also leave this alone) Remove the gparted disk and insert the Ubuntu Server disk commence the install Install the system and add the GUI using tasksel After the system is installed run the- /device add/ - process and the /balance/ commands two lines in the terminal - my question is will these commands remain the same? sudo btrfs device add -f /dev/sdc1 /data sudo btrfs balance start -dconvert=raid1 -mconvert=raid1 /data You can do this after the system is installed, or from a root shell while booted on gparted. It doesn't matter either way, although it's probably better/easier to do it from gparted (there'll only be the one /data fs for the ubuntu installer to detect so you won't end up with /data0 and /data1 again) craig Many thanks Andrew Greig

1 0

Re: Grub 2 Issues - was Weird Boot
by Andrew Greig 16 Jan '20

16 Jan '20

Hi Ed, I think this is going to save me. How do I exclude the data I do not need, I only have a small amount of space left on my laptop? Thanks Andrew On 16/1/20 2:11 pm, ed chan wrote: > Hi Andrew, > > What I was trying to say before is that Photorec( don't know what it > does ) does not try to mount ( not that I can see anyway ) so if you > have problems with sda3, this may be a way around the mount problem. > > I fired up photorec and selected my BTRFS usb disk; after that I asked > it to go and recover the files, it copies them back to my nominated > destination directory. But I don't see any mount at least from the > user space anyway . by watching syslog or dmesg. > > Regards, > > Ed Chan > > On Thu, Jan 16, 2020 at 1:32 PM ed chan <echan64(a)gmail.com > <mailto:echan64@gmail.com>> wrote: > > Hi Andrew, > > If you have the photorec program ( apt-get install testdisk ) you > could fire it up and access /dev/sda3 ( let it access /dev/sda3 , > don't try to mount it. . It doesn't mount /dev/sda3. If that > doesn't work , then I agree with you that the disk is stuff. or > at least the partition is stuff. You may not ne able to mount but > photorec could get to it. > > Unless you have tried all this already, which means commiserations. > > Ed > > On Thu, Jan 16, 2020 at 1:25 PM Andrew Greig > <pushin.linux(a)gmail.com <mailto:pushin.linux@gmail.com>> wrote: > > Hi Ed, > > Thanks for your efforts on my behalf, I enlisted the support > of an experienced tech and we were unable to get anything > working. So I shot down to MSY and 30 minutes later I had > hooked up the SSD with an adapter to my laptop. It cannot > access the drive. Here is the message: > > An error occurred while accessing 'root', the system > responded: The requested operation has failed: Error mounting > /dev/sdc3 at /media/andrewlg/root: wrong fs type, bad option, > bad superblock on /dev/sdc3, missing codepage or helper > program, or other error > > I think it is stuffed. > > Kind regards > > Andrew > > On 16/1/20 11:07 am, ed chan wrote: >> Hi Andrew, >> >> I setup a BTRFS system on a USB key and a "play laptop" and >> tried to retrieved files using photorec . It works. I used a >> copy of gparted iso . This may yield results for getting >> your data off sda3 Fingers crossed. >> >> Ed Chan >> >> On Thu, Jan 16, 2020 at 7:55 AM ed chan <echan64(a)gmail.com >> <mailto:echan64@gmail.com>> wrote: >> >> Hi Andrew, >> >> I tried installed testdisk, and ran photorec against a >> USB key ( not corrupt mind you ) and it seems pretty >> straightforward. Perhaps you should see if you can get >> the data off sda3 this way. >> >> ed >> >> On Thu, Jan 16, 2020 at 7:08 AM ed chan >> <echan64(a)gmail.com <mailto:echan64@gmail.com>> wrote: >> >> Hi Andrew, >> >> From an earlier post, Photorec may be the go. Does >> the rescue disk that you got the output to pastebin >> have Photorec ? All may not be lost. >> >> https://www.cgsecurity.org/wiki/PhotoRec_Step_By_Step >> >> ps. I learn something new everyday ( thanks Bob )- >> this seems to be a tool well worth getting a good >> understanding of. >> >> Regards, >> >> Ed Chan >> >> On Wed, Jan 15, 2020 at 11:11 PM Andrew Greig via >> luv-main <luv-main(a)luv.asn.au >> <mailto:luv-main@luv.asn.au>> wrote: >> >> Hi Ed, >> >> I use grsync. I have a few saved processes, so I >> just fire it up and hit "go". Each backup is >> around 10Gb. >> >> I have a little bit of time up my sleeve but soon >> the pregnant lady will want her special shot. >> >> Thanks >> >> Andrew >> >> On 15/1/20 10:12 pm, ed chan wrote: >>> Hi Andrew, >>> >>> Getting slightly off topic here , looks like you >>> copy and move files from devices to devices ; Do >>> you do that manually or is there a script that >>> does it for you ? >>> >>> Ed >>> >>> On Wed, Jan 15, 2020 at 10:03 PM ed chan >>> <echan64(a)gmail.com <mailto:echan64@gmail.com>> >>> wrote: >>> >>> Hi Andrew, >>> >>> You could take it to a commercial Linux org >>> that knows BTFS and get them to >>> rescue /dev/sda3. It may cost a few hundred >>> dollars but ... >>> >>> Ed Chan >>> >>> On Wed, Jan 15, 2020 at 9:31 PM pushin.linux >>> via luv-main <luv-main(a)luv.asn.au >>> <mailto:luv-main@luv.asn.au>> wrote: >>> >>> >>> >>> >>> >>> Sent from Samsung tablet. >>> >>> >>> -------- Original message -------- >>> From: ed chan <echan64(a)gmail.com >>> <mailto:echan64@gmail.com>> >>> Date: 15/1/20 9:18 pm (GMT+10:00) >>> To: "pushin.linux" >>> <pushin.linux(a)gmail.com >>> <mailto:pushin.linux@gmail.com>> >>> Cc: Andrew Greig via luv-main >>> <luv-main(a)luv.asn.au >>> <mailto:luv-main@luv.asn.au>> >>> Subject: Re: Grub 2 Issues - was Weird Boot >>> >>> Hi Andrew, >>> >>> Silly question from me: do you have a >>> backup of sda ? Can you mount sda >>> readonly ? . Another idea - outside this >>> technical sphere is that perhaps you >>> could ask some commercial Linux support >>> org that may be able to provide >>> support. Obtaining support from a list >>> ( a very good one at that - I learnt a >>> lot from the posting of this list ) can >>> sometimes be stressful. >>> >>> Sorry I can't offer too much help - I >>> don't know BTFS or RAID , I am a luddite >>> , I only know ext3/4. >>> >>> ed >>> >>> Hi Ed, >>> I use my SSD for quicker processing and >>> then when my work is done I move the RAW >>> files to my RAID drives and make copy to >>> an external 3TB, my images once exported >>> as proofs and full size images are >>> copied to the RAID drives and Google >>> Drive, and the external hard drive. But >>> I was in the middle of a project when it >>> went down. My RAW files are still on sda3.. >>> Bugger. Its a pregnancy shoot, too late >>> now to reshoot. >>> Andrew >>> >>> _______________________________________________ >>> luv-main mailing list >>> luv-main(a)luv.asn.au >>> <mailto:luv-main@luv.asn.au> >>> https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >>> >> _______________________________________________ >> luv-main mailing list >> luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au> >> https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >>

1 0

Re: Grub 2 Issues - was Weird Boot
by Andrew Greig 16 Jan '20

16 Jan '20

Hi Ed, Thanks for your efforts on my behalf, I enlisted the support of an experienced tech and we were unable to get anything working. So I shot down to MSY and 30 minutes later I had hooked up the SSD with an adapter to my laptop. It cannot access the drive. Here is the message: An error occurred while accessing 'root', the system responded: The requested operation has failed: Error mounting /dev/sdc3 at /media/andrewlg/root: wrong fs type, bad option, bad superblock on /dev/sdc3, missing codepage or helper program, or other error I think it is stuffed. Kind regards Andrew On 16/1/20 11:07 am, ed chan wrote: > Hi Andrew, > > I setup a BTRFS system on a USB key and a "play laptop" and tried to > retrieved files using photorec . It works. I used a copy of gparted > iso . This may yield results for getting your data off sda3 Fingers > crossed. > > Ed Chan > > On Thu, Jan 16, 2020 at 7:55 AM ed chan <echan64(a)gmail.com > <mailto:echan64@gmail.com>> wrote: > > Hi Andrew, > > I tried installed testdisk, and ran photorec against a USB key ( > not corrupt mind you ) and it seems pretty straightforward. > Perhaps you should see if you can get the data off sda3 this way. > > ed > > On Thu, Jan 16, 2020 at 7:08 AM ed chan <echan64(a)gmail.com > <mailto:echan64@gmail.com>> wrote: > > Hi Andrew, > > From an earlier post, Photorec may be the go. Does the rescue > disk that you got the output to pastebin have Photorec ? All > may not be lost. > > https://www.cgsecurity.org/wiki/PhotoRec_Step_By_Step > > ps. I learn something new everyday ( thanks Bob )- this seems > to be a tool well worth getting a good understanding of. > > Regards, > > Ed Chan > > On Wed, Jan 15, 2020 at 11:11 PM Andrew Greig via luv-main > <luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au>> wrote: > > Hi Ed, > > I use grsync. I have a few saved processes, so I just fire > it up and hit "go". Each backup is around 10Gb. > > I have a little bit of time up my sleeve but soon the > pregnant lady will want her special shot. > > Thanks > > Andrew > > On 15/1/20 10:12 pm, ed chan wrote: >> Hi Andrew, >> >> Getting slightly off topic here , looks like you copy and >> move files from devices to devices ; Do you do that >> manually or is there a script that does it for you ? >> >> Ed >> >> On Wed, Jan 15, 2020 at 10:03 PM ed chan >> <echan64(a)gmail.com <mailto:echan64@gmail.com>> wrote: >> >> Hi Andrew, >> >> You could take it to a commercial Linux org that >> knows BTFS and get them to rescue /dev/sda3. It may >> cost a few hundred dollars but ... >> >> Ed Chan >> >> On Wed, Jan 15, 2020 at 9:31 PM pushin.linux via >> luv-main <luv-main(a)luv.asn.au >> <mailto:luv-main@luv.asn.au>> wrote: >> >> >> >> >> >> Sent from Samsung tablet. >> >> >> -------- Original message -------- >> From: ed chan <echan64(a)gmail.com >> <mailto:echan64@gmail.com>> >> Date: 15/1/20 9:18 pm (GMT+10:00) >> To: "pushin.linux" <pushin.linux(a)gmail.com >> <mailto:pushin.linux@gmail.com>> >> Cc: Andrew Greig via luv-main >> <luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au>> >> Subject: Re: Grub 2 Issues - was Weird Boot >> >> Hi Andrew, >> >> Silly question from me: do you have a backup of >> sda ? Can you mount sda readonly ? . Another idea >> - outside this technical sphere is that perhaps >> you could ask some commercial Linux support org >> that may be able to provide support. Obtaining >> support from a list ( a very good one at that - I >> learnt a lot from the posting of this list ) can >> sometimes be stressful. >> >> Sorry I can't offer too much help - I don't know >> BTFS or RAID , I am a luddite , I only know ext3/4. >> >> ed >> >> Hi Ed, >> I use my SSD for quicker processing and then when >> my work is done I move the RAW files to my RAID >> drives and make copy to an external 3TB, my >> images once exported as proofs and full size >> images are copied to the RAID drives and Google >> Drive, and the external hard drive. But I was in >> the middle of a project when it went down. My RAW >> files are still on sda3.. >> Bugger. Its a pregnancy shoot, too late now to >> reshoot. >> Andrew >> >> _______________________________________________ >> luv-main mailing list >> luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au> >> https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >> > _______________________________________________ > luv-main mailing list > luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au> > https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >

1 0

Re: Grub 2 Issues - was Weird Boot
by Andrew Greig 15 Jan '20

15 Jan '20

Hi Ed, I use grsync. I have a few saved processes, so I just fire it up and hit "go". Each backup is around 10Gb. I have a little bit of time up my sleeve but soon the pregnant lady will want her special shot. Thanks Andrew On 15/1/20 10:12 pm, ed chan wrote: > Hi Andrew, > > Getting slightly off topic here , looks like you copy and move files > from devices to devices ; Do you do that manually or is there a script > that does it for you ? > > Ed > > On Wed, Jan 15, 2020 at 10:03 PM ed chan <echan64(a)gmail.com > <mailto:echan64@gmail.com>> wrote: > > Hi Andrew, > > You could take it to a commercial Linux org that knows BTFS and > get them to rescue /dev/sda3. It may cost a few hundred > dollars but ... > > Ed Chan > > On Wed, Jan 15, 2020 at 9:31 PM pushin.linux via luv-main > <luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au>> wrote: > > > > > > Sent from Samsung tablet. > > > -------- Original message -------- > From: ed chan <echan64(a)gmail.com <mailto:echan64@gmail.com>> > Date: 15/1/20 9:18 pm (GMT+10:00) > To: "pushin.linux" <pushin.linux(a)gmail.com > <mailto:pushin.linux@gmail.com>> > Cc: Andrew Greig via luv-main <luv-main(a)luv.asn.au > <mailto:luv-main@luv.asn.au>> > Subject: Re: Grub 2 Issues - was Weird Boot > > Hi Andrew, > > Silly question from me: do you have a backup of sda ? Can you > mount sda readonly ? . Another idea - outside this technical > sphere is that perhaps you could ask some commercial Linux > support org that may be able to provide support. Obtaining > support from a list ( a very good one at that - I learnt a lot > from the posting of this list ) can sometimes be stressful. > > Sorry I can't offer too much help - I don't know BTFS or RAID > , I am a luddite , I only know ext3/4. > > ed > > Hi Ed, > I use my SSD for quicker processing and then when my work is > done I move the RAW files to my RAID drives and make copy to > an external 3TB, my images once exported as proofs and full > size images are copied to the RAID drives and Google Drive, > and the external hard drive. But I was in the middle of a > project when it went down. My RAW files are still on sda3.. > Bugger. Its a pregnancy shoot, too late now to reshoot. > Andrew > > _______________________________________________ > luv-main mailing list > luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au> > https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >

1 0

Re: Grub 2 Issues - was Weird Boot
by pushin.linux 15 Jan '20

15 Jan '20

Sent from Samsung tablet. -------- Original message --------From: ed chan <echan64(a)gmail.com> Date: 15/1/20 9:18 pm (GMT+10:00) To: "pushin.linux" <pushin.linux(a)gmail.com> Cc: Andrew Greig via luv-main <luv-main(a)luv.asn.au> Subject: Re: Grub 2 Issues - was Weird Boot Hi Andrew, Silly question from me: do you have a backup of sda ? Can you mount sda readonly ? . Another idea - outside this technical sphere is that perhaps you could ask some commercial Linux support org that may be able to provide support. Obtaining support from a list ( a very good one at that - I learnt a lot from the posting of this list ) can sometimes be stressful. Sorry I can't offer too much help - I don't know BTFS or RAID , I am a luddite , I only know ext3/4.edHi Ed,I use my SSD for quicker processing and then when my work is done I move the RAW files to my RAID drives and make copy to an external 3TB, my images once exported as proofs and full size images are copied to the RAID drives and Google Drive, and the external hard drive. But I was in the middle of a project when it went down. My RAW files are still on sda3..Bugger. Its a pregnancy shoot, too late now to reshoot.Andrew

2 1

Re: Grub 2 Issues - was Weird Boot
by pushin.linux 15 Jan '20

15 Jan '20

Sent from Samsung tablet. -------- Original message --------From: ed chan <echan64(a)gmail.com> Date: 15/1/20 7:49 pm (GMT+10:00) To: Andrew Greig <pushin.linux(a)gmail.com> Cc: Andrew Greig via luv-main <luv-main(a)luv.asn.au> Subject: Re: Grub 2 Issues - was Weird Boot Hi Andrew,On Wed, Jan 15, 2020 at 11:54 AM Andrew Greig via luv-main <luv-main(a)luv.asn.au> wrote: Hi Manoj, Thank you for your response. I have had a look at those links, and they are quite a bit "over my head", so I wonder if I should use the rescue disk to facilitate shifting my ~/working directory to my RAID disks. I would make sure my "precious cargo" is on a drive outside the desktop. If you install, the installer may override your RAID disks - unless you are extremely careful or you have full control over where the installer is going to put stuff. (Nothing else is of any consequence) and then use a Ubuntu 18.10 DVD to upgrade the distribution and hopefully create a new GRUB on (in old terms) /dev/sda3 Thoughts? That is if you are going to do re-install. You could perform this additional step as a more precaution. I would do this since you rely on this data for your work. Installers can be quite destructive thingsBest of luck.Ed Chan Hi Ed, I have been unable to mount sda, and I need to do that to get my data saved, so I may buy another SSD, replace my current SSD and leave my raid alone in the install. Then recover my data soon after.I really did not expect to have to go through this. Just awful.Thanks Andrew

1 0

Re: Grub 2 Issues - was Weird Boot
by Andrew Greig 15 Jan '20

15 Jan '20

Hi Manoj, Thank you for your response. I have had a look at those links, and they are quite a bit "over my head", so I wonder if I should use the rescue disk to facilitate shifting my ~/working directory to my RAID disks. (Nothing else is of any consequence) and then use a Ubuntu 18.10 DVD to upgrade the distribution and hopefully create a new GRUB on (in old terms) /dev/sda3 Thoughts? Thanks Andrew Greig On 15/1/20 9:57 am, Manoj C Menon wrote: > Hi Andrew, > > From the logs it looks like your sda3 partition (btrfs) is corrupt. > > Perhaps you could boot from a rescue CD/flash drive and try some of > the suggestions on these pages? > > https://www.suse.com/support/kb/doc/?id=7018133 > https://bbs.archlinux.org/viewtopic.php?id=248361 > > > -Manoj.C > > On Wed, Jan 15, 2020 at 12:17 AM Andrew Greig via luv-main > <luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au>> wrote: > > Hi All, > > I have discovered a Ubuntu Boot-Repair -Disc which avoids syntax > issues, > I was unable to come up with a satisfactory syntax for the commands > needed to solve this problem. Suitably chastened I have located a > laptop > which has Thunderbird so now I can keep the thread on the list. My > attempts to communicate from a tablet produced a pile of crap. > > I downloaded and burned a Disk-Repair-Disk for Ubuntu > > I have run the recommended steps to repair GRUB 2.8, but nothing has > been achieved. > > I did request the log be sent to a paste bin just in case, and as > it is > a few pages of text here is the link. > > http://paste.ubuntu.com/p/pNsZCYF5QZ/ > > The last line acknowledges the failure to achieve a result. > > This machine is critical to my work, and I had considerable > assistance > earlier in 2019 to achieve a RAID system on this machine, for > which I am > truly grateful. > > I would appreciate any assistance with this problem. > > Andrew Greig > > _______________________________________________ > luv-main mailing list > luv-main(a)luv.asn.au <mailto:luv-main@luv.asn.au> > https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main >

3 2

Grub 2 Issues - was Weird Boot
by Andrew Greig 14 Jan '20

14 Jan '20

Hi All, I have discovered a Ubuntu Boot-Repair -Disc which avoids syntax issues, I was unable to come up with a satisfactory syntax for the commands needed to solve this problem. Suitably chastened I have located a laptop which has Thunderbird so now I can keep the thread on the list. My attempts to communicate from a tablet produced a pile of crap. I downloaded and burned a Disk-Repair-Disk for Ubuntu I have run the recommended steps to repair GRUB 2.8, but nothing has been achieved. I did request the log be sent to a paste bin just in case, and as it is a few pages of text here is the link. http://paste.ubuntu.com/p/pNsZCYF5QZ/ The last line acknowledges the failure to achieve a result. This machine is critical to my work, and I had considerable assistance earlier in 2019 to achieve a RAID system on this machine, for which I am truly grateful. I would appreciate any assistance with this problem. Andrew Greig

1 0

Re: Weird boot issue
by Craig Sanders 13 Jan '20

13 Jan '20

On Sun, Jan 12, 2020 at 04:20:42PM +1100, pushin.linux wrote: > > -------- Original message --------From: Craig Sanders via luv-main <luv-main(a)luv.asn.au> Date: 11/1/20 2:12 pm (GMT+10:00) To: luv-main(a)luv.asn.au Subject: Re: Weird boot issue On Fri, Jan 10, 2020 at 05:01:57PM +1100, pushin.linux wrote:> Hi all,I am in a great dilemma, when rebooting after agreeing to a> software update, did not check the packges involved, but running Ubuntu> 18.04, I was confronted with this:>> GRUB version 2.02> Minimal BASH-like line editing is supported.>> For the first word, TAB lists possible command completions. Anywhere else> TAB lists possible device or file completions.>> grub> _ ( flashing cursor)> Don't know what to do here.There's an old (2014) but still pretty good tutorial here:https://www.linux.com/tutorials/how-rescue-non-booting-grub-2-linux/see also:https://help.ubuntu.com/community/Grub2/TroubleshootingAlternatively, you could boot with a rescue CD or USB stick, and examine thedrives and partitions with fdisk or gdisk or similar in order to identify theroot filesystem (and the /boot filesystem if it's separate from the root fs).Then mount the root fs as, say, "/mnt", /boot as "/mnt/boot" (if separate),and optionally other filesystems (you probably won't need other partitionsmounted for the rescue operation).Then bind-mount the pseudo-filesystems /dev, /proc, and /sys under /mnt.These are needed for update-grub to work. Here's a quick way to do that: for i in proc dev sys ; do mount -o bind "/$i" "/mnt/$i" ; doneRun "chroot /mnt" to get a shell where /mnt is treated as the root fs.Then you can edit your /etc/default/grub (if needed - e.g. make sure that theline "GRUB_DISABLE_LINUX_UUID=true" is commented out), and run "update-grub".Finally, exit the chroot, unmount the partitions you mounted (in roughlyreverse order to the order you mounted them - e.g. "umount /mnt/dev" beforetrying to "umount /mnt"), and reboot. something like this should work: for i in proc dev sys boot / ; do umount "/mnt/$i" ; doneDue to paranoia and ancient & long-obsolete habit, I like to run "sync" tomanually flush all buffers to disk before rebooting. e.g. "sync ; shutdown -rnow". It's harmless and useless when doing a clean reboot with "shutdown",but may prevent or reduce fs corruption if you have to do a forced reboot(e.g. with "reboot -f") or power-cycle.> I am running an ssd as sda, sdb and sdc are in a btrfs RAID array. Puzzled> by this behaviour.I don't know if this is related to your boot problem or not, but this is thewrong way to think about drives in linux.Drives MAY (and often do) retain the same device names (/dev/sda, /dev/sdb,/dev/sdc etc) when you reboot a machine, but you can NOT rely on that beingthe case.These device names are NOT guaranteed to survive across reboots. In fact, itis has been documented for many years that these device names are not constantor reliable.Storage devices may get different device names for a variety of reasons,including (but not limited to): drives (including USB drives) being added orremoved, new kernel version, module load order, minor timing differences fordrives spinning up or being detected by the kernel, and more.This is why you should always configure grub and /etc/fstab to use UUIDs orLABELs rather than hard-coding /dev/sdXn device names.craig--craig sanders <cas(a)taz.net.au>_______________________________________________luv-main mailing listluv-main@luv.asn.auhttps://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-mainHi Craig,I am wading through the first option "how to rescue..."I have found rootgrub> ls (hd0,3)/@/ @/homeand ran this ...ls (hd0,3)/@/dev/ run/ boot/ a whole lot of stuff ... inc vmlinuz and home/ and root/grub> ls @/boot/# whole lot of stuff including vmlinuz-4.15.0-74-genericI cant seem to get the syntax right in line 2 for the location of the kernelLine one worked OK, but should I be using root=/dev/sda3 ?I am writing this with one finger on a tablet. I can't read that mess. i'm not even going to try deciphering it. Also, this should be sent to the mailing list, not to me personally. so I'm replying back to the list. craig

2 1