[TriLUG] What might I be getting myself into?...

[Ken Mink via TriLUG]

I've had to resize a /boot a couple times. If you're using lvm, you can 
free up the primary drive without taking the machine down.


1. Attach a USB drive

2. Extend the VG into the drive.

3. pvmove all the data from the primary drive to the USB drive.

4. vgreduce the primary drive out of the vg.

5. backup /boot and unmount it.

Now you're primary drive is not in use. Do what ever partitioning you 
need to.

6. Remount and restore /boot(if needed)

7. Extend the vg back into the primary drive

8. pvmove everything back

9. vgreduce the USB drive out of the vg

10. Disconnect the USB drive


The machine doesn't need to come down through the process. pvmove 
operates a very low priority. The performance of the machine should not 
be affected. It will take time, however.

Ken

p.s. The above is a summary. There are commands left out for brevity.


On 12/21/2016 02:57 PM, Brian via TriLUG wrote:
> Hiya folks,
>
> So, I've got my server basically back up and running satisfactorily 
> from the weekend's excitement.  Except for one thing:  /boot is too 
> small.  I didn't want to lose an important partition on the one HDD in 
> the box, so I reused all the existing partitions from the previous 
> CentOS 5 setup. Go figure, kernels have grown since then, and a 100 MB 
> /boot partition isn't enough to hold more than one kernel image.
>
> It isn't really a huge deal at the moment, although it means I can't 
> update the kernel with yum, and it means logwatch whines about /boot 
> being almost out of space.  But...I'd like to make the situation 
> better, eventually.  I see two apparent options:
>
> 1) Back up the entire drive (500 GiB), wipe the whole thing, 
> repartition from scratch, reinstall everything, basically throw away 
> the work I did these past few days
>
> 2) Get a secondary drive, maybe a small SSD, that I can tuck inside 
> the machine to hold /boot (it's a very compact 1U rack enclosure; no 
> room for more than one 3.5" HDD, but I could probably squeeze a 2.5" 
> SSD in there) and perhaps other system partitions
>
> My instinct is toward option 2, but I wonder how smoothly it would go. 
> fstab has all the partitions identified by UUID, so I suppose it would 
> continue to find them; as long as I correct the kernel boot arguments 
> to find /, should it all just work?
>
> This is my (only) server/router, so I'm reluctant to just experiment.
>
> Thanks in advance for all insights!
> -Brian