dmraid and mdadm?

[rbaldwin]

Server

• FOG Version: Running Version 1.3.0-RC-27 SVN Revision: 6023
• OS: Ubuntu 14.04

Client

• Service Version: ??
• OS: Windows 7 64bit

I’m attempting to image a Lenovo P50 with two HDD configured as a RAID0 array.

I tried setting “Host Kernel Argument” as I do on my Lenovo W530 to “mdraid=true”, but it doesn’t find the md array.

Booting into Debug.
I only have a empty container /dev/md0, I don’t get a /dev/md126 or md127 like I have on my W530.
/proc/mdstats shows no available devices.

During my troubleshooting I booted the machine with an Ubuntu 16.04 Live CD and the was able to access the RAID array using dmraid, so I started looking at dmraid in FOG. It isn’t working, looking into the /etc/init.d/S20dmraid script I found It’s not starting because the init script stops at line:8
modprobe dm-mod >/dev/null 2>&1

The dm-mod module isn’t install in /lib or /lib64 so it errors, I’m not sure why that stops the bash script.

As demonstrated below:
Here I’ve added an echo to the script after the modprobe and ran it, nothing was outputted
https://goo.gl/photos/CrTtpzBb4wZXURmSA

Then I removed the modprobe line:
https://goo.gl/photos/tqSBoFqjv53dmZ318

As you can see now the script runs and it finds my raid volume.

Is this a bug or is dmraid deliberately disabled?

[Tom Elliott]

The change you made, does the W530’s still work?

See, raid is kind of a weird beast.

[rbaldwin]

I have no idea, because I’m not sure how to make that change permanent. I’m making the change on a boot P50 booted in debug mode in FOG.

[Tom Elliott]

You could just start the client in debug mode (both without mdraid=true).

[Tom Elliott]

To add on, the file that handles assembling of raid devices is: /etc/init.d/S99fog.

Particularly lines 17 thru 20.

Mind you we’re not starting dmraid, we’re actually using mdadm

Maybe try a mechanism that can use mdadm to assemble the disks?

[rbaldwin]

@Tom-Elliott

I haven’t been able to make mdadm assemble the disk.

For example:
mdadm --assemble /dev/md0 /dev/sda /dev/sdb

Complains that disk /dev/sda and /dev/sdb do not contain a superblock.

[Tom Elliott]

@rbaldwin They wouldn’t, you need to point at the partitions that are defined for them.

(Of course that’s assuming there are partitions defined).

What’s the output of fdisk -l for /dev/sda1 and /dev/sdb1?

[Tom Elliott]

What about the output of mdadm --assemble --scan

[rbaldwin]

@Tom-Elliott

The raid array has a Windows 7 64bit installation on it and is defined as ~1TB

Raid configuration in Bios:
https://goo.gl/photos/iLZveDYK1vJ6Tijt6

mdadm --examine on /dev/sda
https://goo.gl/photos/9DTovJpVxsrLPApA9

mdadm --examine on /dev/sdb
https://goo.gl/photos/BY8ynhEzmsFNHtES6

mdadm --examine --scan output:
https://goo.gl/photos/Hq3CN682Hc3jshq1A

As you can see mdadm can see the volume but for some reason doesn’t automatically assemble it. I don’t know eneough about how this works to say why. Just looking at dmraid because I’ve seen it work on the Ubuntu 16.04 live cd. Something I can’t say for mdadm so for on the P50. mdadm works fine on the Lenovo W530.

fdisk -l output:
https://goo.gl/photos/jMvtUtfyjsoyPZBH6

[rbaldwin]

@Tom-Elliott

It’s in my last reply:
https://goo.gl/photos/Hq3CN682Hc3jshq1A

[rbaldwin]

@Tom-Elliott

Sorry just noticed you said mdadm --assemble --scan

“no arrays found in configure file or automatically”

[Tom Elliott]

http://unix.stackexchange.com/questions/273819/how-do-i-rebuild-create-assemble-an-imsm-raid-0-array-from-disk-images-instead

It appears you might need to specify a chunk size? I don’t know what that chunksize will be, but if you can test the ideas on the above link, and figure out, I can work to add a “chunk” size argument for the raid if all works.

[rbaldwin]

@Tom-Elliott

I was able to build the array with the mdadm command shown here:
https://goo.gl/photos/7gtJf1hHVi4VAjj18

The build command seems to be the key here, as It works with and without the chunk command.
I haven’t mounted it yet to see if it’s readable, but this is progress from what I’ve seen so far. Not sure what to do now, since this works great in Debug mode, but wont be done automatically on fresh reboots to debug, capture or deploy.

[rbaldwin]

Any pointers on this, I just need to be able to specify these commands to FOG when these hosts boot up for imaging?

[Tom Elliott]

@rbaldwin The difference is your commands are implicit (with or without the chunk commands). The methods that are in use when you run just a “normal” runner, the code is greatly different.

Maybe it’s my unknowing how to do so. If you’d like, you can play with the code a bit (in a debug mode maybe?)

The information FOG currently uses (and works for the few other cases we have of people using RAID layout) is located here:
https://github.com/FOGProject/fogproject/blob/dev-branch/src/buildroot/package/fog/scripts/etc/init.d/S99fog#L17

[Tom Elliott]

Specifically, I’m hoping that you could run the mdadm --assemble --scan with a chunk size specified in the command line. If this successfully builds your imsm array, then I can adjust our arguments to accept the “chunk” size.

Perhaps:

mdadm --auto-detect --assemble --scan

Of course I don’t have an array I could test this with, sorry.

[Tom Elliott]

I’m working on thoughts so if my messages seem to drift around it’s probably just thinking a lot.

[Tom Elliott]

Looking a bit more, I’ve added three hopeful bits for solving this.

First, the mdadm --auto-detect should be by itself as mdadm is then asking the kernel to activate the arrays. (Source: https://linux.die.net/man/8/mdadm)

So --assemble --scan is not “compatible” with the --auto-detect argument (mdadm --auto-detect --assemble --scan vs mdadm --auto-detect).

I’ve updated the code base in the init’s for handling this to try these three things:

mdadm --auto-detect
mdadm --assemble --scan
mdadm --incremental --run --scan

If you jump on the dev-branch, it should update the inits for this new stuff. If these new changes still don’t work, please see if there’s a way we can do an auto assembly on the iMSM raid. If we cannot auto-assemble, it is extremely difficult (currently) to make a working method for you. I suppose I could add a “postinitload” scripts thing, similar to postdownload scripts. I’d really prefer seeing if the current code could handle this with these modifications or an auto assembly model over implicit command to generate the array.

[rbaldwin]

@Tom-Elliott said in dmraid and mdadm?:

Specifically, I’m hoping that you could run the mdadm --assemble --scan with a chunk size specified in the command line. If this successfully builds your imsm array, then I can adjust our arguments to accept the “chunk” size.

Perhaps:

mdadm --auto-detect --assemble --scan

Of course I don’t have an array I could test this with, sorry.

–chunk is an invalid command on the --assemble command as is --auto-detect

[rbaldwin]

@Tom-Elliott said in dmraid and mdadm?:

Looking a bit more, I’ve added three hopeful bits for solving this.

First, the mdadm --auto-detect should be by itself as mdadm is then asking the kernel to activate the arrays. (Source: https://linux.die.net/man/8/mdadm)

So --assemble --scan is not “compatible” with the --auto-detect argument (mdadm --auto-detect --assemble --scan vs mdadm --auto-detect).

I’ve updated the code base in the init’s for handling this to try these three things:

mdadm --auto-detect
mdadm --assemble --scan
mdadm --incremental --run --scan

If you jump on the dev-branch, it should update the inits for this new stuff. If these new changes still don’t work, please see if there’s a way we can do an auto assembly on the iMSM raid. If we cannot auto-assemble, it is extremely difficult (currently) to make a working method for you. I suppose I could add a “postinitload” scripts thing, similar to postdownload scripts. I’d really prefer seeing if the current code could handle this with these modifications or an auto assembly model over implicit command to generate the array.

I booted in debug mode and ran the following.
mdadm --auto-detect
mdadm --assemble --scan
mdadm --incremental --run --scan

/proc/mdstats shows 0 devices.

mdadm --detail /dev/md0
Shows inactive with 0 devices.

A postinitload script would be great, if I could specify that per host. As I have many Lenovo W530/W520s with RAID that work just fine with the existing FOG RAID Configurations. It’s only the brand new EUFI Bios’ed Lenovo P50s that are having this issue.

Is there perhaps a newer version of mdadm tools? Maybe these new Intel fake RAID controllers aren’t supported by the older version?