[ale] Buwahahah!! Success!

Thu Aug 31 22:37:05 EDT 2023

LVM is a life saver, many years ago, I had a drive that was dying. I used
lvm to make a snap shot and then I used dd to make that into a img file,
luck I had a NAS to write off to, but when I got the lvm setup, I could do
a loop back mount on the image file and restore to drive.

Now-a-days I use a OS drive and my lvm are their own drives, so if I use
the os, I don't lose my data.

May one day over pizza and beer I will tell you the horror story of the
17TB lun that someone created with ZFS. It was because of ZFS snap
shot that I fell in love with ZFS.

On Thu, Aug 31, 2023 at 10:16 PM Jim Kinney via Ale <ale at ale.org> wrote:

> Still have to put the data on the disk somewhere! I do use bind mounts
> when something changes and a chunk needs to be visible somewhere else. Or a
> dir in a partition needs to be read only.
>
> But lvextend is live so it's real time.
>
>
> On August 31, 2023 5:45:55 PM EDT, Steve Litt via Ale <ale at ale.org> wrote:
>
>> What's your opinion of using bind mounts to create realtime
>> stretchable/shrinkable partitions as opposed to LVM?
>>
>> Jim Kinney via Ale said on Wed, 30 Aug 2023 20:47:05 -0400
>>
>> Lvm is a total lifesaver!! You never know really how to partition a
>>> drive so lvm can help expand a partition. On. The. Fly! Add a new
>>> drive or add a new raid box and lvm says, sure, let's use that!
>>>
>>> It also supports software raid which irritates the hardware purists
>>> with deeper pockets that me. A software raid10 is cheap, fast,
>>> reliable, and if I really need it, I can clone the box into a new mobo
>>> with some boot magic and it resurrects the added blank drives in old
>>> and new boxes for me without a pair of cards that cost more than the 4
>>> new drives. Spinning rust sata drives with 5 year warranties are
>>> totally worth it.
>>>
>>> Yeah. Lvextend is a lifesaver. Lvreduce is awesome as long as the
>>> filesystem is not xfs. Ext4 supports shrink. ZFS of course replaces
>>> ext4 and raid and lvm but does eat more CPU in Linux land. Pretty sure
>>> ZFS borders on being a filesystem cult but the prophets have some
>>> really good points. Maybe one day it'll get into the mainline kernel.
>>> Probably right after gluster. 😁
>>>
>>> I'm almost embarrassed to admit that I no longer fix my home gear. If
>>> it pukes, it just gets replaced. Hardware is mostly pretty reliable
>>> (not gonna discuss HPC/supercomputers running a hot tub style liquid
>>> cooling solution). There's used Dell/Supermicro server gear in Suwanee
>>> data centers that hits eBay. It's usually 5-7 years old and lasts
>>> another 3-5 years in the home shop. 3 on the Supermicro, 5 on the
>>> Dell. But at $350 for a dual CPU, 8-12 core, 64-128G ram, add your own
>>> hard drives, I'm happy.
>>>
>>> I do need to kick the backups again. Long overdue for the bare metal
>>> recovery of the entire backup system. Thanks for the reminder of "aging
>>> backups".
>>>
>>> On Wed, Aug 30, 2023, 5:36 PM Charles Shapiro <hooterpincher at gmail.com>
>>> wrote:
>>>
>>> About three weeks ago piglet, my primary desktop computer, pooped
>>>> out. Press the power button and the fans came on, but nothing else
>>>> happened -- no POST, no screen, like, Nuthin'.  Went through all the
>>>> hardware troubleshooting I knew, carted it around to a couple of
>>>> friends who are smarter than me, but never revived it. It was a Core
>>>> I7 motherboard obtained surplus 5 years ago after a hard life as a
>>>> server, so I reckon it was no big surprise it finally bit the dust.
>>>>
>>>> $500 or so and a couple of sessions at Decatur Makers later I'd
>>>> replaced everything but the Mass Storage, the video card, and the
>>>> case.  She would boot to the BIOS screen np. I could get the GRUB
>>>> screen but no further -- she'd would just Kernel Panic.  The new
>>>> guts are a 12th gen Intel I9 on a Gigabyte Aorus Z690 gen 1.4 MB, so
>>>> maybes that had something to do with it.
>>>>
>>>> Fortunately, I keep my OS on a 120 GB SSD, and my /home on a much
>>>> larger Spinning Rust drive. So I knew that I wouldn't have to go
>>>> back to my (shamefully aged) backups.  I installed Debian 12 on the
>>>> SSD (up from Debian 11) and got her to boot ok.
>>>>
>>>> I configured my original install to use lvm without really
>>>> understanding what that meant, so  my /home wouldn't actually, like,
>>>> mount with a simple mount(8) command. Cue a deep-dive into lvm,
>>>> helped along by an excellent tutorial (
>>>> https://linuxhandbook.com/lvm-guide/ ) which also let me delve into
>>>> the Wonderful World of Vagrant.
>>>>
>>>> After groveling through all that mess, I did the following:
>>>>
>>>> * vgrename the old piglet-vg vgroup to piglet-home-vg ( using the
>>>> UUID grabbed from vgdisplay so I was sure to rename the correct one)
>>>> * vgchange -ay piglet-home-vg to 'activate' my renamed vgroup
>>>> * vgscan --mknodes to fiddle the file system to recognize my new
>>>> logical volumes
>>>> * Verify that I could now mount(8) my piglet-home-vg/home lvolume on
>>>> /mnt (Yay!)
>>>> * systemctl set-default multi-user.target to bring the machine up
>>>> with no GUI and log in as root
>>>>  * Move the installed /home to /home-debian12-default ( in case I
>>>> needed to grab some stuff from there to make the Debian 11 settings
>>>> for Plasma work with Debian 12).  Make a new empty /home to serve as
>>>> a mount point.
>>>>   * Edit /etc/fstab to mount /dev/mapper/piglet--home--vg-home on
>>>> /home
>>>>   * systemctl set-default graphical.target to bring the machine back
>>>> up
>>>>
>>>> Of course I still have a bunch of software to install and some stuff
>>>> to bring back from my backup ( all my local apache stuff is gone for
>>>> example). But it's really all over but the shouting.
>>>>
>>>> Fun Things I Learned:
>>>>
>>>>   * If you screw up an entry in /etc/fstab, Debian 12 will halt
>>>> during the boot process when it tries to mount disks.  On some
>>>> occasions, it'll attempt to mount your screw up for a while and time
>>>> out after a minute and a half or so, but other times I think it just
>>>> dies.  You can fix this by choosing Emergency Mode from the GRUB
>>>> menu and fixing the bad edit in your /etc/fstab.  Or I suppose you
>>>> could boot from your stick again if that rocks your sox.
>>>>
>>>>   * Debian 12 doesn't appear to let you mount an lvolume from fstab
>>>> by UUID. I could do this on my VM, which was running Ubuntu. On
>>>> Debian you mount from /dev/mapper, which seems to be the Correct Way
>>>> (at least that's the way shipped lvolumes are mounted).  There's
>>>> some magic going on here that I still don't fully understand. Some
>>>> of the hyphens in the /dev/mapper lvolume names are doubled, again
>>>> for reasons which are inscrutable to me.
>>>>
>>>>   * Hardware can be Tricky.  If you don't plug in ALL the power
>>>> connectors on your MB, it will simply refuse to start at all.  Then
>>>> you will tear your hair out until you figure out the dumb misteak
>>>> you made. And if you get checksum errors late in your install off a
>>>> Stick, it means that the media is no good no more.
>>>>
>>>>    * vagrant and lvm are pretty way kewl.  Learning on a virtual
>>>> machine let me hack away at lvm and other scary stuff (like
>>>> parted(8) and mkfs(8) ) break things, and still not disturb anything
>>>> important on my personal machines.  Highly recommended.
>>>>
>>>> All in all a lot of fun.
>>>>
>>>> -- CHS
>>>>
>>>>
>>>>
>>
>> SteveT
>>
>> Steve Litt
>> Autumn 2022 featured book: Thriving in Tough Times
>> http://www.troubleshooters.com/bookstore/thrive.htm
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-- 
Terror PUP a.k.a
Chuck "PUP" Payne
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