[Swlug] Remote SWLUG, Join us on Jitsi tonight - Tuesday 20 April 2021 19:00 (BST)

[Daniel Morris]

Doh! As I described, and not as the command line I re-typed. It was:

# ddrescue /dev/sdc /run/media/danielm/goodexternalcaddy/failingdisk.img
/root/failingdisk.mapfile
# ddrescue -r3 /dev/sdc
/run/media/danielm/goodexternalcaddy/failingdisk.img
/root/failingdisk.mapfile

Just in case anyone needs to try this kind of recovery in the future. The
mapfile is really important, as that is how GNU ddrescue minimises reads
from broken portions in the initial pass (max data, min more damage) and
then retries just those parts in the second invocation.

 Daniel

On Thu, 22 Apr 2021 at 12:23, Daniel Morris <danielmorris.cengmiet at gmail.com>
wrote:

> Sorry about the very late reminder, enabled by realising my swlug list
> email now goes through gmail instead of POP to my broken disk..
>
> I spent a head-banging day yesterday scrabbling through backups
> Realised that my flaky data is on a wholly LVM managed disk
> Made enough room to drag data off the complete disk, rather than 200G
> "partition" I thought I was messing with (LV)
> Finding the writes (ddrescue) to other internal disks spawn SATA errors
> themselves that bring those disks down to read-only
> Having a sulk/pity-party for one
> Leaping on colleague's suggestion that I swap the failing disk into one of
> the external caddies to try again with my other system (rather than do the
> system surgery):
>
> # dd_rescue /dev/sdc /run/media/danielm/goodexternalcaddy/failingdisk.img
> /root/failingdisk.mapfile
> # dd_rescue -r3 /dev/sdc
> /run/media/danielm/goodexternalcaddy/failingdisk.img
> /root/failingdisk.mapfile
>
> ddrescue (that's GNU/gddrescue, not dd_rescue) sucked all ~720GiB off in
> one run with zero read errors overnight through my laptop, out to another
> external backup disk which was plugged into the laptop's other USB port,
> which gave me hope. After storing the flaky disk, I re-mounted my good
> external caddy to try working on the image:
>
> # losetup -r
> /dev/loop1 /run/media/danielm/goodexternalcaddy/failingdisk.img
>
> I've just mounted the image (ro) on a loopback device and openSUSE's LVM
> automagically scanned, detected the volume groups, but a simple mount has
> failed complaining that it  "can't read superblock".
>
> I expect it may be a bit confused as the journal shows a device mapper has
> misidentified a FAT-fs. Bearing in mind I know have what's probably an ext2
> structure in a logical volume bound inside an image that's mounted over a
> loopback via USB to an encrypted, probably native XFS store. To just write
> that sequence down makes me marvel at how clever the layers are.
>
> I've come full-circle to think that perhaps the disk might be Ok and the
> issues that first appeared in December are actually down to a failing
> motherboard and/or SATA expansion cards. I've been holding back the
> full-scale Ryzen/mobo/m2/graphics/memory/psu swapout since the last of the
> upgrade bits arrived. I wanted to do a full backup-and-check before diving
> in...
>
> Daniel
>
>
> On Wed, 21 Apr 2021 at 09:18, Clifford Perry via Swlug <
> swlug at mailman.lug.org.uk> wrote:
>
>> I enjoyed my first virtual meet up - thanks all :)
>>
>> Cliff
>>
>> On Wed, Apr 21, 2021 at 8:42 AM Dick Bain via Swlug <
>> swlug at mailman.lug.org.uk> wrote:
>>
>>> Humble apologies for not seeing this until this morning, knackered after
>>> a day in the garden is my only excuse 😉
>>> Hopefully see you all next month
>>> Dick
>>>
>>> On Tue, 20 Apr 2021, 18:28 Daniel Morris via Swlug, <
>>> swlug at mailman.lug.org.uk> wrote:
>>>
>>>> It's the third Tuesday in the month, so 7pm tonight will be
>>>> SWLUG-time! We're going to meet again using Jitsi.
>>>>
>>>> Simply launch a web-browser and go to
>>>>
>>>> https://meet.jit.si/swlugmeetonline
>>>>
>>>> Or,
>>>> https://jitsi.org/jitsi-meet/ and choose "Start a call" and enter
>>>> "swlugmeetonline" as the name.
>>>>
>>>> Join me to grumble about yet another failing disk and another emergency
>>>> backup that is taking forever, the wonders of Ryzen, the fantabulousness of
>>>> vaccines, or whatever...
>>>>
>>>>  Daniel
>>>> --
>>>> Swlug mailing list
>>>> Swlug at mailman.lug.org.uk
>>>> https://mailman.lug.org.uk/mailman/listinfo/swlug
>>>
>>> --
>>> Swlug mailing list
>>> Swlug at mailman.lug.org.uk
>>> https://mailman.lug.org.uk/mailman/listinfo/swlug
>>
>> --
>> Swlug mailing list
>> Swlug at mailman.lug.org.uk
>> https://mailman.lug.org.uk/mailman/listinfo/swlug
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.lug.org.uk/pipermail/swlug/attachments/20210422/0c3563e6/attachment.html>