[ale] Buwahahah!! Success!

[Steve Litt]

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