Installing Linux on a existing Windows RAID0

[DemiSheep]

I administer a small network of computers connected to a windows 2003 server. The machines Dual boot Windows XP and CentOS 5.

My question is this. The machines are being upgraded to HP Z800 workstations. These workstations come with 2 1TB drives setup on a hardware RAID0. Can I install Linux on these machines, using the RAID0? Can I do an install as if it was just one hard drive? The machines came with Windows7 and I'd like to keep it intact including the RAID0. Can I do the install where it resizes the partition, adding the linux partition to the "drive".

If I can't use the existing windows RAID0 to install CentOS I was thinking of just installing another hard drive in the machines for it. This brings up another question, what would happen if I moved my Linux drive from one of the old workstations and put it in the new workstation, would it boot? I know windows wont boot like this because of the hdd controller drivers and I have a sneaky work around for this anyway but am not wanting to transfer the windows installation.

Any help would be appreciated.

DemiSheep

[Irithori]

After a brief look at the specs (and the price tag ) this might be an actual hardware raidcontroller.
Not a cheap fakeraid, which are common in consumer mainboards.

So yes: You can install linux as a dualboot setup on that raiddevice, as if it was a single harddisc.

btw: Any reason for raid level 0?
It doubles the chance of a harddisc failure.

[DemiSheep]

Well I was pretty sure it was a hardware raid controller as on boot you have the "Press Ctrl-I to enter RAID bios" message and when I go into the bios it says "Intel Matrix Storage Manager".

Ok, so I can do it, but how? Will I just boot off the CentOS disc and install, and then resize the windows partition?

And yes I know about the doubled hard drive failure possibility, and in fact I am looking at the possibility of changing it to a RAID10, so I can keep the performance of the RAID0 but have the fault tolerance of the RAID1. The RAID0 is desireable as it does give some performance increase with large file read/writes (Which seems odd to me). And the RAID10 is a RAID0 + RAID1.

Thanks,
DemiSheep

[Irithori]

This is a bit off-topic, but:
the intel Matrix storage manager is a fakeraid.

And while it´s still technically possible to dualboot windows/linux from it,
my recommendation would be to not do it.
a) the sinlge discs are still available to linux and *may* be modified by mistake by the user.
On a regular raidcontroller, the single discs can only be managed with the raidcontroller tools.
b) booting may be problematic
c) enterprise distributions such as centos/redhat might not even support such toys.
Aka: the kernelmodule might not be there by default


To put some perspective into the "fakreaids are bad" claim:
I tried the following just for fun in the past:
- setup a raid 1 of disc A and B
- created a filesystem on the raid
- created a textfile "text.txt" with content "1" on it
- powered down
- unplugged disc B
- on bootup: controller did complain. ok so far
- file had content "1". ok
- changed content to "2"
- power down
- inserted disc B
- power up
- file had content "2". ok
- power down
- unplugged disc A
- power up
- file had content "1". wth?

Long story short:
In my experience, fakeraids lack any controller logic whatsoever.
(One might say, that´s the point of them )
Which disqualifies them from real usage.


If you really want to do it, then it is as you expect: the windows partitions needs to be resized to gain space for linux.

P.S.: I know what a raid10 is

[DemiSheep]

I was pretty sure you did know what RAID10 is, but I visit so many forums where I don't understand what the heck their talking about because I don't know what one or several of the terms they are talking about is so I was just explaining for someone like me that might read this and be like "oh I don't understand...darn it, it's over my head" you know?

Btw do you guys know what the difference between RAID10 and RAID1+0 is?

Based on this: h t t p:// w ww.acnc.com/04_01_10.html and this: ht tp:// w ww.acnc.com/04_01_0_1.html RAID10 is better, has more advantages and less disadvantages. I saw a forum post where someone said they were the same thing and that doesn't seem to be true. RAID10 is a pair of mirrored drives with a pair of striping drives and the other is two pairs of striping drives with both pairs mirrored.

(You'll have to piece the links together, ie remove spaces)

Thanks,
DemiSheep

[HROAdmin26]

I agree with Irithori for the most part.

A) It's software RAID, AKA fakeraid.
B) If you need the better disk thruput and don't mind data/OS loss due to a failed disk, it's fine to use.
C) I would recommend using the Linux md driver for striping, but if you need to maintain compatibility with a Windows OS, you'll have to use the Intel "raid" support.

It is certainly possible to install to this "raid" set, as I have done it many times. It's also much easier to do using an install from a "LiveCD" as you can then first load/unload modules until you get the driver you want loaded in order to see the raid correctly. Booting is also fine. Because the BIOS will pass control to the "raid" device, GRUB needs to be installed to the same device. An example of what the device usually looks like (from memory - could be off):

/dev/RAID_NAME_<STRING>

And after partitioning...

/dev/RAID_NAME_<STRING>_PART1
/dev/RAID_NAME_<STRING>_PART2
/dev/RAID_NAME_<STRING>_PART5
...

* Discussing RAID10 involves looking at the config as the data moves from the application to the disks. In a basic 4 disk setup and looking at the data moving *down* from the application, the data should be striped and then mirrored. This allows your 4 disk config to possibly lose 2 HDD's and still run. In a config with a mirror across stripes, only a single loss can be sustained.