Hello,

I am installing a Asus Server that have RAID by hardware. My question is, this is transparent to the operating system (in this case Linux)? Do I need to have in the kernel the RAID support or I don't need it?

I think most variants of RAID is supported by default by most distributions precompiled kernels.

Some types of RAIF, e.g. Silicon Image 3112 chips are referred to as fake raid. The argument is that it is not true hardware RAID, but software (through the bios). On my ubuntu Linux system I am therefore running with the default ubuntu compiled kernel, but also with the dmraid software.

hope that helps a bit.

On-board RAID controllers are mostly software RAID. You need dmraid to handle them altough it is better to use Linux software RAID for some flexiblity.

Silicon Image 3112 controllers are crap. Do not use because it is still under beta. Use at your own risk.

So, my setup of RAID-1 array in the BIOS won't do anything? I still have to do the software RAID in the operating system?

You can use the dmraid driver as I do, if you have one of the chips supported that way (what hardware do you have by the way?)

I haven't read much about Silicon Image SATA RAID controllers in detail, but I have used my 3112 for 3 years or so now. More than a year of that I have used it in a RAID-0 configuration. I haven't had any problems, but I try to run regular backups of my data, just in case.

I have only just come across Linux software raid. I am for now sticking with my bios/fakeraid setup. One question: Apart from flexibility and possibly stability (neither of which is an issue for me, touch wood), wouldn't running raid through bios still be faster then linux software raid? Presumably running raid through bios would be less work for the main cpu...(?)

In other words, if I am ONLY interested in SPEED, which raid setup is best (linux of fakeraid/bios)?
Obviously true hardware raid would be best. Are those available with Linux support?

If it's a TRUE Hardware based raid controller all you would probably need is the RAID MANAGEMENT tools provided by the RAID card manufacturer..

but alas you didn't list anything about the type of hardware you are using other than Asus server.... doesn't really tell much.


True hardware RAID is indeed available with Full Linux support see 3Ware for a prime example.. http://www.3ware.com/products/serial_ata9000.asp

Also RAID controllers from many server manufacturers are supported.. i.e. Dell, HP, IBM, etc..

It's a ASUS Server RS120-E3(PA4) :

4 x SATAII-300 hard disk drive with:
- RAID 0, RAID 1, RAID 10, or software RAID 5 configuration using the Intel Matrix Storage Manager
- RAID 0, RAID 1, or RAID 10 configuration using the LSI Logic Embedded SATA RAID controller

The motherboard CD contains modules of LSI MegaRAID for Red Hat, Suse and Windows. For Debian, nothing...

nevermind..

The kernel already supports LSI MegaRAID, so ignore the software on the CD disc.

RAID on the LSI controller should be transparent unless you use the Intel controller which is software RAID.

Since everybody seems to know Asus RS120, I have an offtopic question. Using RHEL update 4, how do you know if one of the drives fail under RHEL? There seems to be no beep whatsoever from the RS120 hardware to inform admin of defective or degraded partition, is there any utility under RHEL to do so? And in case you do spot the problem via extra sensory powers, and replace the degraded hard drive while inside OS (RHEL), how would you know the status of rebuilding?

If you do reboot, you will see that it's rebuilding, but in case disk0 is the one that's being rebuilt, how will you go back into operating system?

If in case disk1 is the one that's being rebuilt, will you be able to go back into OS? From what we experienced, this is not the case. It reports of swap partition problem, or swap file problem, and doesn't go in. I thought it was supposed to be Raid 1 mirroring (hardware), how come with Disk0 alone, we can't boot into RHEL?

Thanks, any help will be appreciated.

Go to LSI website go to the downloads section and look up your controller, under misc downloads you will find the following tools for Linux..

megamgr - http://www.lsi.com/files/support/rsa...x_mgr_5.20.txt
megamon - http://www.lsi.com/files/support/rsa...8_MegaMONr.txt
megarc - http://www.lsi.com/files/support/rsa...egarc_1.11.txt

I have no clue if these are packaged somewhere specifically for your distro, but LSI has them avail directly

farslayer, thanks. I'll check them out. I assume these are for monitoring under Linux?