x86_64 unable to install to existing software RAID devices

[gentooruwest]

Hi,

First off, I love sabayon, but wth is wrong with installing to a previous software raid device. Here's what I've noticed (I'm using 3.4e)

1. None of the raid arrays are detected during the livecd startup. I think all it would take is a few mdadm commands
2. If I manually startup the RAID array and then start the installer, the installer shuts down the raid arrays and I get the dreaded error about a serious error occuring on md0 (error would be on md1 if I choose not to have anaconda play with md0) and then the installer exits
3. If I just try running the installer without first starting the raid arrays the same thing happens.

What am I doing wrong?

Thanks
Jeremy West

[tom909]

Hi,

same as you, I am also user of software RAID (Intel ICH7), aka 'fake RAID'. The only solution people could give me, involved the installation of SL3.4 x86_64 on a non-RAID harddrive, tempoarily, and then manage to transfer the complete installation to the existing RAID hdd .. Well, as I am not experienced enough to do so, I was forced to try out other distros and after crawling though 100s of forums I figured out that this kind of problem is very common and thousands of people have it. It seems that there are only two Linux-distros in the world support existing software-RAIDs nativly, OpenSUSE and Fedora. I picked the last one for a test and found out that worked, for me.

As far as I learned about Linux there must be some way to manage the installation of SL on a software RAID. One way would be to recompile the Linux kernel and enabling its RAID capabilities during that process. Linux kernel 2.6.22 (kernel.org) actually supports many kinds of RAID systems, even a wide spectrum of software RAIDs. The problem is that these kernel options/modules are disabled in the original SL distro. So I assume such an adapation would be sort of complex, considering that SL makes use of imagefiles on the DVD, what makes such work even more challenging. I am relatively new into Linux in general, so in my case it might take some time until I manage to get such things done by myself - or - there might be some future SL release, opened to all sorts of RAID systems, what would be really cool.

[WarraWarra]

Did you try the dodmraid cheat code at live dvd boot ?

[tom909]

I'm not exactly sure how these cheatcodes work. Is that somekind of kernel boot-parameter?

I have tried mounting my RAID manually during SL-installation, using 'dmesg' and trying to mount partitions in /dev/mapper/ to /mnt/ .. But after 5 hours of experiments I gave up.

[WarraWarra]

Live dvd boot menu then press F5 and some text apears at the bottom of the screen , then add dodmraid before the -- and press enter.
Not sure but dodmraid sounds like do disk manage raid so there might be a do software raid option somewhere not sure at all.
Gentoo has these cheat codes listed somewhere as well as on the actual iso / live dvd is a readme with some of this options.

Will this work = no clue but it might. I have seen somewhere a very good gentoo / raid guide that has possibly the software raid info in it not sure.
Also how much info can you loose on the software raid say if you have to erase / rebuild it from scratch. You might be able to use the instller part of SL and lvm + software raid it from there but again at the loss of all the current files in the software raid. Not sure how this works but it might / worth checking out.

I was looking into getting a laptop pcmcia Esata raid express lost card + 2x wd4000kd's + external enclosure to speed up my laptop , maybe you might want to look into something similar as a software raid slows things down a lot = hd speed down to 75% performance sometimes.
34 express laptop Card = us$30 to us$60 , wd4000kd = us$70-us$80 , enclosure = us$130 but has built in raid 0 or 1 via a switch + 2 usb / 1 esata out = Thecus N 2050 model and comes with sata raid pci desktop adapter and all of this needs shipping. = 120MB/s to 140MB/s or more for this combo via slow esata express card from my now 33MB/s laptop hd.

Hope something here helps. WIll see if I can find the gentoo raid guide again.

[tom909]

Thank you,

I'm gonna try this out (dodmraid). Hopefully it will let me keep my existing RAID-partitions. You're right: A possible option is to re-initialize the entire RAID array and let the installer build a completely new software-RAID on its own. Well, unfortunately I can't do that, since there's still a lot of important stuff under XP running on the same RAID array. During my experiments I was able to extend my existing RAID partitions (NTFS-5) with two new ones (one Linux swap, another EXT3 for the rest), making excessive use of fdisk, and as mentioned I tried to mount those new partitions from /dev/mapper to /mnt , I've read somewhere that the Sabayon installer would recognize and accept partitions, declared as /mnt/sdh or /mnt/sdh1 .. sdh3 ect.. I tried that, as well as with hda, hda1 ... - no success. I don't really like Fedora, I would love to switch to Sabayon x86-64.

Anyway - thank you, and I'll post here if the dodmraid parameter worked for me.

[gentooruwest]

Wow ... I didn't check this post yesterday and now it's gotten out of hand. First of all let me off a correction to the second poster. You might want to start another forum topic for your problem. This issue is not related to "fake raid". "Fake Raid" is NOT the same as software raid. Software raid is done within the kernel only and involves no special hardware. Let's say that I have two hard drives /dev/sda and /dev/sdb and I create the following partition layout.

/dev/sda1 ext3 (boot)
/dev/sda2 <software raid>
/dev/sda3 <software raid>
/dev/sda4 <software raid>

/dev/sdb1 NTFS
/dev/sdb2 <software raid>
/dev/sdb3 <software raid>
/dev/sdb4 <software raid>

What you can do is then have anaconda join the software raid partitions to make mdX devices like such:

/dev/sda2 and /dev/sdb2 = /dev/md0 (swap)
/dev/sdb3 and /dev/sdb3 = /dev/md1 ( / )
/dev/sdb4 and /dev/sdb4 = /dev/md2 ( /home )

The problem is that if these devices already exist from a previous install of another distribution such as fedora, then you get the failure I first mentioned.

Does this make sense? I finally solved the problem by deleting each software raid partition (except the ones used for /home) and recreating each partition exactly the same. I don't know why, but the installer (anaconda) doesn't seem to want to reuse existing software raid partitions. You have to recreate them ... WEIRD. I don't have this problem under fedora, so it appears to be a bug with the sabayon variation of anaconda.