An updated installer for XCP-ng 7.5.0

dvdhngs

@frank-s, very thanks for the help!
where I run this line? on shell option at xcp-ng instalation screen, or f3 when installing, or using another live linux?

olivierlambert

To avoid filling the whole disk with zeros, you can probably "just" do a mdadm --zero-superblock /dev/sdX (for each disk).

If it's not enough, please report back

@dvdhngs when you are in any menu in the install, use Alt key + right arrow to get a console.

frank-s

@olivierlambert
I did that Olivier but for me it didn't work. That's why I zeroed both disks entirely. Worth a try though as it doesn't take long.

olivierlambert

Do you remember, on this disk, which version of mdadm superblocks did you used before?

frank-s

@olivierlambert
Hmmm. It might have been 0.9 as it was for boot partition. It wasn't whole disk raid though. Each partition was a different raid set.

olivierlambert

I see now! Because we zero the superblock on the whole disk, it doesn't zero all the superblocks on all existing partitions.

I wonder if doing a loop that runs the zero superblock command on each partition would solved this

frank-s

@olivierlambert
Probably that would work or as an alternative use dd to zero the first 45GiB of each disk shouldn't take too long. I was not pressed for time and had other things to do so I just zeroed the disks entirely after which setup was flawless.

olivierlambert

Yes but your feedback was precious to understand why our zero superblock on the whole drive wasn't enough Now we could maybe improve the installer to avoid this problem in the future!

olivierlambert

Issue created: https://github.com/xcp-ng/xcp/issues/107

olivierlambert created this issue in xcp-ng/xcp

open Software RAID install on previous used mdadm disks #107

frank-s

@olivierlambert
Glad to be of help. The new raid installer is a really good thing and I am using it now on two servers. The downside, however, is that it uses whole disk raid. If it used partition based raid1 then if XCP-NG were installed without local storage repo, it would be possible (after installation) to manually create raid 10 for the storage. With mdadm this could be done with three or more disks. So at that point all the installation partitions would be raid1 with all disk partitions as members but the bulk of each disk (assuming large disks) would be left unused for raid 10 - faster local storage. Would that be an over complicated change to the installer or is this a possibility?

olivierlambert

I completely understand your idea, but I don't see a simple solution (I mean, even just thinking in terms of possible menu in the current UI). If you can go deeper on the functional perspective (drawing with basic wireframe the process), it could help to specify it and maybe make it real then (one big rule in dev: more specs = easier to dev)

frank-s

@olivierlambert
I wasn't suggesting that the installer should do raid 10 necessarily. For XCP-NG itself raid 1 is sufficient. Just suggesting that the partitions of the installation could each be a different raid 1 set rather that simply doing raid 1 on a whole disk basis. If the end user chose to have the installer create local storage it could be just raid1 on another (big) partition. For those who want improved performance however there is the possibility to manually create raid 10 local storage post install.
What is wireframe? (I am not a developer).

olivierlambert

I was suggesting you just draw the workflow as you imagine it during the install. Example of a wireframe:

dvdhngs

@olivierlambert couldn't open /Dev/sda for write - not zeroing

Tried:
mdadm --stop /dev/md127

Result:
Cannot get exclusive access to /dev/md127
Perhaps a running process, mounted filesystem or active volume group?

I will try with DD now

frank-s

@dvdhngs
Run lvscan to see if there are any active logical volumes. If there are run vgchange <group name> -an to deactivate all logical volumes. Now try to stop the array.

sfx

Looks like creating the software raid volume also fails when you have another existing array. I have another software array (RAID 5) in my machine. Error on the console was ls: cannot access /sys/block/*/holders/*/dev: No such file or directory after it seemed to get info about the wrong RAID array (the existing RAID 5 one). After disconnecting those disk it worked fine.

olivierlambert

@sfx please take a look here, there are several discussions there: https://github.com/xcp-ng/xcp/issues/107

olivierlambert created this issue in xcp-ng/xcp