Okay, you Linux gurus. Tell me what I'm doing wrong.

I wanted to try putting the more stable parts of my OS on an ssd and the more write intensive stuff on a hard drive. So I configured an ubuntu install with

/, /boot, /usr, /var, and /opt as mount-point partitions on the ssd

and similarly put

/tmp, /home, and swap-space on a harddrive

That's OK, I think: I get a fast OS boot after the motherboard posts, and applications launch fast too

But for fun, I first tried something a little more complicated than that -- and it didn't work

What I tried was a two harddrive RAID 0 for /tmp, /home, and swap-space. (Yeah, I know RAID 0 isn't safe, but WTF!)

For my motherboard, I change some BIOS settings and then reboot into a special RAID BIOS to define the array. No problem: the motherboard sees two 500gb drives as a single tb device -- and so does the ubuntu installer

But when I try to install, the installer gets only a tiny fraction of the way through the /home partition and announces the RAID array has failed. If I look at what's happened on the harddrives, only one shows the expected directory structure ... but maybe that's not informative because of striping

I can try to eliminate possibilities like a bad harddrive on my own

But ...

Should I be carefully considering which SATA channels the various drives use? Is there a known issue with ubuntu and RAID for various disk formats? Is there something illegal about my partitioning scheme under RAID? What else could be going wrong?

Do you have a deathwish?

Motherboard RAIDs, even the vaunted NVidia RAID chips, REQUIRE driver and processor support to get the RAID to write data properly. Generally, those drivers are found in Windows, and thus these chips are often referred to as "Win-RAIDs".

The good news is, since it's software RAID, you can get similar or even better performance by using the software RAID stack already built into the linux kernel. The bad news is, Ubuntu doesn't do this easily by default.

If you want to be able to install to special hard drive configurations, there are some documents out on the net that will help you use the Ubuntu installer CD to pull it off. If you'd like to do it quickly and simply, just to see if you can, try CentOS or Fedora 12.

Oh, and performance tip: If you have a decent amount of RAM, mounting /tmp in a RAMdisk is a GREAT way to improve system responsiveness.

When ya ain't got nuthin, ya got nuthin to lose


I'm perhaps unfairly biased against fedora, since I really disliked redhat when I first encountered it a decade ago, but I have fedora and centos disks, so I'll try a different OS if I can't get this working in ubuntu

Hmm. You're absolutely right about needing a driver during OS installation: I should have read the mobo manual more carefully. Thanks!

Thanks also for the ramdisk suggestion! I'll think about that a bit

Gentoo may be ridiculous on the setup side of things, but on the plus side my laptop installation is bulletproof, and I even have longer battery life thanks to the customizations. I've tried distro after distro, and I keep coming back to this one.

like about it: I've got a box full of distros on disk, including Gentoo, some of which I tried in VirtualBox, but I think the Gentoo setup dissuaded me from a quick try there

This is a core i7 laptop with 4 gigs of DDR3. It took me 2 hours to get Gentoo started, and then it took 23 hours to compile everything that was necessary using the emerge command. Of course, those 23 hours were unattended, but that's still a ridiculous amount of time.

So why do I do it? Because with this installation I get access to any open source program that any other linux distro can run. If it's not in portage, I can download the freely available source code and compile it from scratch. I have full control over everything that's running in and out of the kernel, and full control over how my sessions run. I have full control over how my disks will be handled, and full control over exactly which kernel I run so that I have TRIM for my SSD.

In short, I'm still running Gnome, Compiz-Fusion, and other customized desktop effects just like Ubuntu, but my memory footprint is 400MB lighter. I can run programs normally only supported on Red Hat distros, and even merge in some KDE programs without a lot of dependency gripes from my package manager. I have longer battery life, support for all of my hotkeys, customized ACPI and startup scripts for various tasks, and rock-solid stability in every program installed on my system. And one of my favorite features is that I can utilize any virtualization platform I want, including the libvirt interface normally only available through Red Hat.

It took me a long while to get proficient enough in linux to be able to do all of this, but Gentoo and documentation helped me get there, and even with total reinstallation time still being over a day, I wouldn't take any other distro.

and an ssd, which I'll try putting Gentoo onto

none /var/tmp/portage tmpfs defaults,size=2048M,nr_inodes=1M 0 0

With that, ALL of your installation packages will compile entirely in RAM until the installation/copy step at the end. It cuts the time for a full system compile down by anywhere from 25-40% depending on your architecture and chosen packages.

You just convinced me, too. I think I might try this one out.