[SOLVED] dmraid/mdadm - problem with intel fake RAID array

[doktor5000]

Hi all. Long time mandrake/mandriva user here.

I've put up with this problem in Mageia 2 as I knew Mageia 3 wasn't far away, and it still ocurs.

I have five hard drives: One boot/os drive and two groups of two hard drives in Raid 1 (mirror) arrays, using the motherboards on board fake raid chip.

Before I get flamed for fake raid, please note I have used this arrangement for the last 5+ years and it has proved faithful and reliable. When this machine packs it in I will pursue NAS/Server or cloud type storage, but for now, lets focus on what I have.

When using both the live CD and DVD install media, if I enter hard disk management in MCC I am presented with 5 hard drives. Exit out of that then I run (as root):

[dmraid -ay]

My arrays are found, I can mount them manually through CLI or in hard disk management in MCC I'm presented with 3 hard drives (boot drive, two raid arrays) after running the dmraid activation.

So it's clear that dmraid is working. My data is accessable.

Except that after install, again I am shown 5 hard drives in disk management. I run the raid activation, mount the arrays and it's all up and running again. If I edit fstab for the raid arrays, I end up with boot issues as the arrays aren't activated.

As this is somewhat of a family machine it is a real nusance to have to manually activate and mount the arrays everytime the machine gets booted.

BTW this doesn't appear to be Mageia specific, as there are complaints of the same thing all over the net. The problem is what works for suse and ubuntu (for example) doesn't work for me.

What I believe I need to do is active the raid arrays early in the boot process, before fstab, so that it boots correctly.

I seen a nice mkinitrd rebuild process for suse, but that didn't work. The ubuntu guides have slightly different system setups and I can't find the relevant config files.

I would love to get this sorted, and hopefully pass the feedback up stream, so that I (we) don't go through this for Mageia 4.

Any help most appreciated.

[sander85]

Could it be this bug: https://bugs.mageia.org/show_bug.cgi?id=9440

[xboxboy]

Sander: Thanks, yes that appears to be pretty well what I'm going through. I have updated the bug with my problem/setup. Hopefully we can push on and get a result. I bet that the solution is simple, and consists of editing about three lines of a config file or two.....Probably just jinxed myself there lol.

[ghmitch]

I started out around 10 years ago with software RAID on Mandriva. Initially I used dmraid, but later I found mdadm, the newer software RAID management system to be easier to use. The dmraid system is rather old and not well maintained and contains, as I remember, a lot of gotcha's such as the one you are encountering. So I would recommend learning more about mdadm and shifting your system over to it. Nothing on the drives changes, only the tool that administers them. And what you are using is "software" or "soft" RAID, NOT fake RAID. Fake RAID is when you use a proprietary driver that makes it seem like you are using hardware RAID when you are not. There is nothing unrespectable about software RAID. It is what it is. It has its advantages and disadvantages, but it is a whole lot easier to deal with than fake RAID which is really nothing more than a proprietary black box that seems amazing until problems occur. When that happens, you have a problem, because you can't see what is going on behind the proprietary curtain. Give mdadm a try, I think you will like it and find it easier to work with.

After using software RAID, in 2009 I switched to using hardware RAID with old 3ware cards. That was a step up in some ways, but hardware RAID is not without its problems and with hardware RAID, solving those problems ALWAYS has a price tag of pure $$$$$$$$. So rather than buying newer and better hardware controllers, I stepped out of that game two months ago and am now using Mageia 3 on btrfs file system RAID 1 system wide. It, of course, has its own problems. There is a boot issue, which I think I have under control, and a journal issue that is not under control, but all in all, I really like it and am happy with its capabilities.

But you have to work with what you have at the time. And if my current option was software RAID, I would use it without hesitation. It is much improved since the days I was using it, but I would not think of using dmraid. My choice of an adminstration tool would be mdadm hands down. It generates really nice config files and has more advanced capabilities.

[xboxboy]

Ok, I got a solution. It's not perfect in theory, but it works perfectly.

Apparently mdadm is supposed to be the module of choice for operating intel fake raid arrays (named as isw_* ). But this wasnt getting picked up on my system.

Thanks to David on the #mageia-dev irc channel he worked this out. In /lib/systemd/fedora-storage-init is a filter for dmraid to skip isw* arrays. All I did was comment this out, and my system boots fine, my arrays are activated, and I can even mount them by fstab. The lines are:

Code: Select all

#         if [[ "$dmname" == isw_* ]] && \
#            ! strstr "$cmdline" noiswmd; then
#            continue
#         fi


Yes, I will have to redo this after some updates come through, but until mdadm works correctly I'm happy to sit with dmraid which has worked for 5 years.

[ghmitch]

In the years that I was using software RAID, I found that dmraid either worked perfectly or it didn't. Those few times that it didn't were hell. So on one of those nasty occasions I switched to mdadm and never looked back. mdadm is much easier to administer and it is much easier with mdadm to troubleshoot when something goes wrong. So I highly recommend taking some time to look over mdadm. I believe that detection relies in part on the configuration files present. So anytime you move your RAID partitions from one OS platform to another it would be a good idea to move the configuration files along with them and to look them over and make sure they are correct for the new environment as well. Otherwise you are in a may work, may not situation since detection of RAID volumes in my experience is not an inexact science with a lot of things that can go wrong in the process. Those are my thoughts. Software RAID is not alone in this regard as hardware RAID with all of its expense can cause major headaches as well. That is one MAJOR reason that I have switched to btrfs files system RAID. With file system RAID everything is built into the file system with no external config files necessary and corruptions don't require complete resyncs to fix since they get fixed on a file by file basis. But btrfs still has a way to go before it is completely stable.

[xboxboy]

Just taken Mageia 4 Alpha 3 for a spin, issue remains